Immune-impairments

For many years, immune atypicalities have been described in autism-spectrum
children (32). An important but seemingly overlooked corollary is that
infections that most children immunosuppress quite nicely might have a different
course in children with a mild immune impairment, be it genetic or acquired (3).
     Heretofore, the immune-related studies by Reed Warren, Roger Berger, Alma
Maciulis, and VK Singh were seen by many autism experts as pointing towards an
unusual subset of autism-spectrum kids. Instead, I've begun to realize that
perhaps the Warren et al findings and subsequent research are calling attention
to the tip of an iceberg. Consider:
1.   The Warren et al autism-spectrum studies about null alleles of the
complement C4b gene and about reduced levels of complement C4b in blood. These
studies were based upon a specific gene and a specific protein, and yielded an
important insight, namely, that autism-spectrum children have an above-average
frequency of immune-impairment.
2.   In recent years a number of parents have sent me immune-panels, medical
charts, and medical histories of their autism-spectrum child. Remarkably, most
of these immune panels report various immune atypicalities, such as (i) atypical
elevations of IgG antibodies against common pathogens (eg, CMV, EBV, and/or
HHV6), (ii) missing antibodies against a vaccinal antigen, and (iii) other signs
of immune dysfunctin (eg, reduced NK cell count, impaired NK function, etc).
     
In retrospect, what I've observed in the immune panels of these children (n<15
thus far) ought not be surprising, because if a child has a general immune
impairment (eg, a null allele of the C4b gene), then he or she would seem likely
to have atypical responses to pathogens. 
     Importantly, Reed Warren and colleagues could not evaluate all possible
"mild" immune impairments, thus I've come to realize that the Warren et al
findings probably generalize to a *large* subgroup of autism-spectrum kids who
have a mild immune impairment -- be it genetic and/or acquired -- even if that
impairment has not yet been identified, because researchers have not looked, or
because the child's physicians have not ordered the needed tests (33).
     The autism-spectrum immune-panels I've thus far perused are consistent with
this impaired-immunity principle, in that *most* of the children have had signs
of atypical chronic infections and/or impaired immunity; and their medical
histories often include signs or remarks indicating "viral syndrome" or
"recurrent otitis not responsive to antibiotics", or persistent gastrointestinal
problems resistant to standard treatments. 

The following materials focus upon HHV6 and are intended as a resource document
for physicians and parents of autism-spectrum children. Several of the items
hereinbelow are quite technical, all have clear meaning. The collection is not
intended as complete but ought provide an HHV6 overview on behalf of autism-
spectrum children with atypical HHV6 signs or histories.

[a]  "Human herpesvirus-6 (HHV-6), the etiologic agent of roseola, is
ubiquitous, establishes latency in the host, and can infect a variety of
immunocompetent cells, with CD4+ T lymphocytes being the targets in which it
replicates most efficiently." and HHV6 has an "Immunosuppressive effect... on
T-cell functions" such as "suppression of interleukin-2 synthesis and cell
proliferation." (1)

[b]  "Since HHV-6 shares the capacity to establish latent infection with other
herpesviruses, frequent viral reactivation is probably the explanation for the
high incidence of serologically proven active HHV-6 infection found
simultaneously with active infection due to other herpesviruses as well as in
the presence of various immune deficiency conditions." (2) Let us keep in mind
tht immune impairments can be both genetic and/or acquired (3). This seems to
be a hallmark of the autism-spectrum kids whose immune panels I've perused (4). 

[c]  That HHV6 impairs immune cells' proliferative responses to antigens (4)
means that a child with atypical, chronic HHV6, as indicated by atypical
elevation of anti-HHV6 antibodies, would have another mechanism by which his or
her immunity is impaired; and some aspects are strain-specific re: HHV6 (5).

[d]  Other immune-altering effects of HHV6 derive from the fact that "HHV-6
induces synthesis of a broad range of host cell proteins, including interferon
alpha, CD4, interleukin-1 beta, and tumor necrosis factor alpha..." (6)

[e]  "HHV-6 is a commensal inhabitant of brains; various neurologic
manifestations, including convulsions and encephalitis, can occur during primary
HHV-6 infection or in immunocompromised patients." (7), and HHH6 has been
reported within "oligodendrocytes and microglia" (8), and focal HHV6-
encephalitis has been documented (10). Treatments are mentioned and cited
hereinbelow.

[f]  If the autism-spectrum child's anti-HHV6 titres are elevated, you might
consider evaluations of peripheral blood via PCR for HHV6 (9, 9b), which would
provide an indication of the extent to which various aspects of immunity were
being altered by such an infection. Interestingly, cytomegalovirus (CMV) can be
present in monocytes of individuals who have no anti-CMV antibodies (9a), thus
raising the possibility that HHV6 *might* have a similar effect in some autism-
spectrum children, ie, be etiologically significant despite a lab finding of "no
elevated anti-HHV6 antibodies".

[g]  HHV6 can infect endothelial cells (11), which (as with CMV) may mean that
festering HHV6 can alter blood-brain barrier function. Also, AJ Wakefield et al
have reported that HHV6 can persist within gastrointestinal tissue and often co-
localized with other pathogens (17).

[h]  HHV6 can infect myeloid cells (in bone marrow) and therein inhibit
production of a wide variety of blood cells (12, 21). What *may* be seen
clinically are lab tests showing low counts for myeloid-lineage cells such as
eosinophils, monocytes, basophils, erythrocytes, and/or platelets (24). However,
other factors can alter the lab-test profile, eg, co-infections which alter
cytokines profiles in complex ways (eg, 19-20).

[i]  HHV6 strain A seems to prefer affecting the CNS (13). *If* an autism-
spectrum child has elevated anti-HHV6 titres, then purchasing PCR so as to
determine strains may become significant (eg, 13, 14), and fetal HHV6 infection
of astrocytes has been described (15). However, other strains that categories
A and B may exist (18).

[k]  HHV6 can infect healthy NK cells and can impair NK function (16), and
downregulates expression of CD3 (23), which is required for "cell-surface
expression of and signal transduction" by T-cell receptors (24).

[l]  HHV6, EBV, and HSV were studied for their effects upon cytokines
production. Co-infections (eg, by HHV6 and EBV) can produce diverse effects (19-
20). This is extremely important in children with a genetic and/or acquired
immune impairment augmented by a atypical, chronic infection. Other co-infection
possibilities may exist in med literature.

[m]  HHV6 is associated with Chronic Fatigue Syndrome (33) and atypical effects
of HHV6 and other viruses may be linked to certain environmental toxins (34).

[n]  Foscarnet and ganciclovir can be effective against HHV6, but not in every
case with CNS involvement (25-26, 29); new anti-HHV6 drugs (eg, cidofovir) are
being developed (27,30); substances like granulocyte colony stimulating factor
are occasionally used in conjunction with an antiviral (eg, 28); and co-
infections can require additional therapies, especially in view of HHV6's effect
upon myeloid progenitor cells (31; 12,21).

Teresa Binstock
Researcher in Developmental and Behavioral Neuroanatomy
June 4, 1999

References

1. Flamand L et al. Immunosuppressive effect of human herpesvirus 6 on T-cell
functions: suppression of interleukin-2 synthesis and cell proliferation. Blood
1995 Mar 1;85(5):1263-71.
          Laboratory of Immunovirology, Sainte Justine Hospital,
          Quebec, Canada.
ab: Human herpesvirus-6 (HHV-6), the etiologic agent of roseola, is ubiquitous,
establishes latency in the host, and can infect a variety of immunocompetent
cells, with CD4+ T lymphocytes being the targets in which it replicates most
efficiently. The present study was undertaken to learn more about specific
immunobiologic effects of HHV-6 infection on T-lymphocyte functions. Our data
demonstrate that infection of peripheral blood mononuclear cells (PBMC) by HHV-6
results in suppression of T-lymphocyte functions, as evidenced by reduced
interleukin-2 (IL-2) synthesis and cellular proliferation. In fact,
HHV-6-infected PBMC secreted 50% less IL-2 than mock-infected cells after
mitogenic stimulation with OKT3 antibody or phytohemmaglutinin (PHA). The
inhibition of IL-2 by HHV-6 was also observed in enriched T-cell cultures,
suggesting a direct effect of this virus on this cell type. Messenger RNA (mRNA)
analysis by reverse-transcriptase polymerase chain reaction (PCR) indicated that
HHV-6 diminishes IL-2 mRNA levels in mitogen-stimulated peripheral blood T
cells. These results were also confirmed by Northern blot using the leukemic
T-cell line Jurkat. This inhibitory effect of HHV-6 did not require infectious
virus, as the use of UV-irradiated HHV-6 produced similar results. Moreover,
HHV-6-infected PBMC showed up to an 85% reduction in their mitogen-driven
proliferative response, as compared with sham-infected cells. Proliferation of
both CD4+ and CD8+ T cells was affected by HHV-6. Taken together, our data show
that infection of T cells by HHV-6 results in immune suppression characterized
by a downregulation of IL-2 mRNA and protein synthesis accompanied by diminished
cellular proliferation.
          Published erratum appears in Blood 1995 Jul 1;86(1):418

2. Oren I, Sobel JD. Human herpesvirus type 6: review. Clin Infect Dis 1992
Mar;14(3):741-6.
          Department of Internal Medicine, Wayne State University
          School of Medicine, Detroit, Michigan.
ab: Human herpesvirus type 6 (HHV-6), a newly recognized human herpesvirus first
described in 1986, is morphologically similar to other herpesviruses but is
distinguishable from all of them by some unique in vitro biological effects,
specific antigenic analysis, and patterns of endonuclease restriction digests
of DNA. In vitro HHV-6 exhibits tropism mainly for T lymphocytes, but it also
infects other cells, including B lymphocytes, monocytes-macrophages, glial
cells, and fibroblasts. Because HHV-6 causes frequent infection in infants and
children, a seroprevalence rate of antibody to this virus of up to 80% has been
reported in the United States. Infection in infancy develops as levels of
maternal antibody wane, thus resulting in either subclinical infection or an
acute febrile illness termed exanthema subitum. Primary infection acquired later
in life causes a disease resembling acute infectious mononucleosis. Since HHV-6
shares the capacity to establish latent infection with other herpesviruses,
frequent viral reactivation is probably the explanation for the high incidence
of serologically proven active HHV-6 infection found simultaneously with active
infection due to other herpesviruses as well as in the presence of various
immune deficiency conditions. PMID: 1314102, UI: 92223245

3. A discussion of acquired immune impairment:

4. Horvat RT et al. Human herpesvirus 6 inhibits the proliferative responses of
human peripheral blood mononuclear cells. J Infect Dis 1993 Jun;167(6):1274-80.
          Department of Pathology and Oncology, University of Kansas
          Medical Center, Kansas City 66160-7232.
ab: Human herpesvirus 6 (HHV-6) was recently isolated from the blood of
immunosuppressed individuals and children with exanthem subitum. In this study,
the effect of HHV-6 on the proliferative response of human peripheral blood
lymphocytes was tested. T cell lines or human peripheral blood lymphocytes were
infected with HHV-6 variant A, strain GS, or variant B, strain Z29. Infected and
uninfected cell lysates were UV inactivated and sonicated; when lysates were
added to peripheral blood mononuclear cells from HHV-6-seropositive adults,
lymphoproliferative responses to antigens (tuberculin purified protein
derivative or mumps) and mitogens (phytohemagglutinin or interleukin-2) were
inhibited in a dose-dependent manner. This inhibition was reversed by a rabbit
anti-HHV-6(GS) antiserum, and inhibition was not due to cell lysis induced by
viral infection, since cell death was not observed. This in vitro suppression
of cellular immune responses by HHV-6 proteins may be relevant to the in vivo
pathogenesis of HHV-6 and its relationship to human diseases.
PMID: 8388898, UI: 93274081

5. Furukawa M et al. Distinct effects of human herpesvirus 6 and human
herpesvirus 7 on surface molecule expression and function of CD4+ T cells. J
Immunol 1994 Jun 15;152(12):5768-75.
     ab: This study was undertaken to investigate the effects of newly isolated
T lymphotropic viruses, human herpesvirus (HHV)-6 and HHV-7, on CD4+ T cells.
We first examined changes in surface molecule expression on CD4+ T cells after
infection with HHV-6 or HHV-7 by flow cytometry. Among surface molecules
examined, CD3 expression appeared to decline markedly after infection with HHV-6
variant A (strain U1102) but the decreased level of CD3 expression after
infection with HHV-6 variant B (strain Z29) was slight. Impairment of surface
CD3 expression on HHV-6 variant A-infected cells was also demonstrated by
measuring intracellular free Ca2+ concentration in response to anti-CD3 mAb. In
contrast, HHV-7 infection induced a marked loss of surface CD4 expression, but
the decline of CD3 expression was slight. Cytotoxic activity of virus-specific
CD4+ CTL clones decreased after infection with both HHV-6 variant A or HHV-7 but
the degree of reduction of cytotoxicity by HHV-6 variant B was not significant.
Addition of lectin restored the cytotoxicity of HHV-7-infected CTL but not that
of HHV-6 variant A-infected CTL. Northern blot analysis and immunoprecipitation
showed that infection with HHV-6 and HHV-7 did not affect the transcription and
protein synthesis of CD3 and CD4. These findings suggest that both HHV-6 and
HHV-7 may directly cause T cell immunodeficiency but that the mechanisms of CD4+
T cell dysfunction mediated by HHV-6 and HHV-7 are different.

6. Inoue N et al. Molecular biology of human herpesviruses 6A and 6B. Infect
Agents Dis 1993 Dec;2(6):343-60.
          Centers for Disease Control and Prevention, Atlanta,
          Georgia 30333.
ab: Human herpesvirus 6 variant A (HHV-6A) and human herpesvirus 6 variant B
(HHV-6B) are closely related herpesviruses. No disease has been specifically
associated with HHV-6A, whereas HHV-6B is the major etiologic agent of exanthem
subitum. Both viruses may be opportunistic pathogens in the immunocompromised
patient... HHV-6 induces synthesis of a broad range of host cell proteins,
including interferon alpha, CD4, interleukin-1 beta, and tumor necrosis factor
alpha...

7. Braun DK et al. Human herpesvirus 6. Clin Microbiol Rev 1997
Jul;10(3):521-67.
     ab: Human herpesvirus 6 variant A (HHV-6A) and human herpesvirus 6 variant
B (HHV-6B) are two closely related yet distinct viruses. These visuses belong
to the Roseolovirus genus of the betaherpesvirus subfamily; they are most
closely related to human herpesvirus 7 and then to human cytomegalovirus. Over
95% of people older than 2 years of age are seropositive for either or both
HHV-6 variants, and current serologic methods are incapable of discriminating
infection with one variant from infection with the other. HHV-6A has not been
etiologically linked to any human disease, but such an association will probably
be found soon. HHV-6B is the etiologic agent of the common childhood illness
exanthem subitum (roseola infantum or sixth disease) and related febrile
illnesses. These viruses are frequently active and associated with illness in
immunocompromised patients and may play a role in the etiology of Hodgkin's
disease and other malignancies. HHV-6 is a commensal inhabitant of brains;
various neurologic manifestations, including convulsions and encephalitis, can
occur during primary HHV-6 infection or in immunocompromised patients. HHV-6 and
distribution in the central nervous system are altered in patients with multiple
sclerosis; the significance of this is under investigation.

8. Albright AV et al. The effect of human herpesvirus-6 (HHV-6) on cultured
human neural cells: oligodendrocytes and microglia. J Neurovirol 1998
Oct;4(5):486-94.
          Department of Neurology, University of Pennsylvania Medical
          Center, Philadelphia 19104-6146, USA.
ab: Human herpesvirus-6 (HHV-6) is a betaherpesvirus that has been frequently
associated with pediatric encephalitis. In 1995 Challoner et al reported that
HHV-6 variant B (HHV-6B) was linked to multiple sclerosis (MS) due to the
presence of viral DNA and antigen in the oligodendrocytes surrounding MS
plaques. These findings led us to examine HHV-6B's in vitro tropism for primary
neural cells. HIV-6B mediated cell-to-cell fusion in cultured adult
oligodendroglia. Infection of oligodendrocytes was further confirmed by
transmission electron microscopy (EM), which showed the presence of
intracellular HHV-6 particles, and by PCR for HHV-6 DNA. However, the release
of infectious virus was low or undetectable in multiple experiments. Microglia
were also susceptible to infection by HHV-6B, as demonstrated by an antigen
capture assay. We did not detect infection of a differentiated neuronal cell
line (NT2D). Our findings suggest that HHV-6B infection of oligodendrocytes
and/or microglia could potentially play a role in neuropathogenesis.
Comments:  Comment in: J Neurovirol 1998 Oct;4(5):471-3
PMID: 9839646, UI: 99053381

9. Huang LM et al. Detection of human herpesvirus-6 DNA by polymerase chain
reaction in serum or plasma. J Med Virol 1992 Sep;38(1):7-10.
     ab: Human herpesvirus-6 (HHV-6) is a newly identified human pathogen.
Currently clinicians rely mainly on blood lymphocyte culture and serological
tests to diagnose HHV-6 infection. The polymerase chain reaction (PCR) was
carried out on the plasma or sera of patients to determine the value of PCR in
the diagnosis of HHV-6 infection. A total of 30 patients entered the study; 10
were experiencing acute HHV-6 infections and 20 were healthy and served as
controls. HHV-6 DNA was detected by PCR in the serum or plasma of the 10 cases
with acute HHV-6 infections. All 20 controls had no HHV-6 DNA in their sera. The
time for serum to become PCR-positive coincided with the appearance of IgG HHV-6
antibody. The relatively late presence of HHV-6 DNA in serum might result from
late lysis of infected cells by immune responses. It is concluded that detection
of HHV-6 DNA by PCR in the serum is a valuable tool for the diagnosis of acute
and/or active viral infection.

9a. Taylor-Wiedeman J et al. Polymorphonuclear cells are not sites of
persistence of human cytomegalovirus in healthy individuals. Journal of General
Virology.  74 ( Pt 2):265-8, 1993 Feb.
     ab: Polymorphonuclear leukocytes (PMNL) have been shown to harbour human
cytomegalovirus (HCMV) in viraemic patients, but to date PMNL of asymptomatic
healthy subjects have not been examined directly to determine whether this is
a normal site of HCMV persistence. Using the polymerase chain reaction (PCR),
paired DNA samples prepared from adherent peripheral blood mononuclear cells
(PBMC), which are known to be a site of persistence of HCMV, and PMNL of 10
healthy adults were analysed. All of seven individuals who were HCMV
seropositive, and one of three who were seronegative gave a reproducible signal
for HCMV DNA in their adherent PBMC, whereas none of the paired PMNL DNA samples
gave a positive result. The remaining two seronegative subjects showed no HCMV
DNA in either the PBMC or PMNL samples. In every case where PCR for HCMV was
negative, PCR amplification of a control human gene was used to show there was
no inability to amplify the DNA. We conclude that within the leukocyte
population of normal asymptomatic HCMV carriers, PMNL do not appear to harbour
persistent HCMV whereas adherent PBMC in the same subjects are a site of
persistence.

9b. Frenkel N, Wyatt LS. HHV-6 and HHV-7 as exogenous agents in human
lymphocytes. Dev Biol Stand 1992;76:259-65.
          Laboratory of Viral Diseases, National Institute of Allergy
          and Infectious Diseases, National Institutes of Health,
          Bethesda, MD 20892.
ab: Human herpesviruses 6 and 7 (HHV-6 and HHV-7), the newly recognized
lymphotropic members of the herpesvirus family, were isolated from peripheral
blood mononuclear cells (PBMC) of healthy individuals. HHV-7 was recovered from
PBMC after exposing the cells to conditions leading to T cell activation. No
virus could be recovered from quiescent non-activated cultures, suggesting that
the virus resided latently in these cells and that it could be induced from
latency by T cell activation. HHV-6 could not be recovered from PBMC using
similar approaches. However, it could be repeatedly reactivated from PBMC after
infection of the cells with HHV-7. Upon further passaging in culture, HHV-6 took

over the population and virus stocks appeared to be clear of the original HHV-7
helper virus. The results of this study suggest that genomes of the lymphotropic
herpesviruses are resident in PBMC of healthy adults. HHV-7 can supply the
functions required for its reactivation from latency. It can also act as a
helper virus for the reactivation of HHV-6 from latency. Following the initial
reactivation step, HHV-6 can replicate autonomously in the cells. These results
may be relevant to the findings that HHV-6 infection is induced in
immunosuppressed patients and in patients undergoing organ transplantation.
Furthermore, these studies may exemplify situations whereby propagation of known
agent(s) in vitro results in the activation of human pathogens resident latently
in the cells.

10. McCullers JA et al. Human herpesvirus 6 is associated with focal
encephalitis. Clin Infect Dis 1995 Sep;21(3):571-6.
          Department of Pediatrics, University of Alabama at
          Birmingham, USA.
ab: Human herpesvirus 6 (HHV-6) is a cause of roseola infantum. Recent reports
associate HHV-6 with cases of encephalitis; however, conclusive etiologic data
do not exist. We evaluated clinical data and laboratory specimens obtained from
patients with focal encephalitis of unknown etiology. Cerebrospinal fluid (CSF)
specimens were tested by polymerase chain reaction for the presence of HHV-6
DNA. Selected samples were analyzed by DNA sequencing. We detected HHV-6 DNA in
the CSF of nine of 138 patients. DNA sequencing revealed that group B strains
of HHV-6 were present in those specimens that were analyzed. No significant
differences could be demonstrated in clinical presentation, laboratory findings,
or neurodiagnostic imaging results between the nine patients with confirmed
HHV-6 infection and the 129 patients without evidence of HHV-6 infection.
Neurological outcome for the nine HHV-6-infected patients varied from complete
recovery without neurological deficit to death. Further prospective study is
warranted.

11. Wu CA, Shanley JD. Chronic infection of human umbilical vein endothelial
cells by human herpesvirus-6. J Gen Virol 1998 May;79 ( Pt 5):1247-56.
          Division of Infectious Diseases, Department of Medicine,
          University of Connecticut Health Center, Farmington
          06030-3212, USA. CaWu@nso1.uchc.edu
ab: Human herpesvirus-6 (HHV-6) exhibits a predominant tropism for CD4+
T-lymphocytes, but can infect other components of the blood as well as
surrounding tissue and organs. To understand the role of the endothelium in the
transmission and haematogenous spread of this virus, human umbilical vein
endothelial cells (HUVEC) were infected with HHV-6 and monitored for viral gene
expression. The presence of both early and late viral antigens was demonstrated
by indirect immunofluorescence in 37.6 and 6.5%, respectively, of HUVEC.
However, attempts to detect the release of infectious virus were not successful,
indicating infection is semipermissive in nature. Upon continued passage of
infected HUVEC monolayers, HHV-6 antigen-positive cells persisted up to 27 days
post-infection. Furthermore, the virus could be recovered from HUVEC monolayers
that contained fewer than 1% antigen-positive cells by co-cultivation with
peripheral blood mononuclear cells. Together, these findings suggest that
endothelial cells may serve as a reservoir for harbouring HHV-6. 
 
12. Yasukawa M et al. Latent infection and reactivation of human herpesvirus 6
in two novel myeloid cell lines. Blood 1999 Feb 1;93(3):991-9.
          First Department of Internal Medicine, Ehime University
          School of Medicine, Ehime, Japan. yasukawa@m.ehimeu.ac.jp
ab: It has been reported that reactivation of human herpesvirus-6 (HHV-6) causes
a failure of hematopoiesis. To clarify the mechanisms of bone marrow suppression
induced by HHV-6 infection, it is necessary to establish an in vitro model of
HHV-6 infection in hematopoietic progenitor cells. We have established two novel
Philadelphia chromosome-positive myeloid cell lines, SAS413 and SAS527, which
possess different hematologic characteristics and show distinct susceptibility
to infection by HHV-6, from a patient with blast crisis of chronic myelogenous
leukemia (CML). HHV-6 subgroup A (HHV-6A) showed marked replication in SAS413,
forming syncytia and inducing cell lysis in short-term culture. On the other
hand, HHV-6A-inoculated SAS527 continued to proliferate without cell lysis and
only a few cells showed HHV-6 antigen expression. In contrast to HHV-6A
infection, inoculation with HHV-6 subgroup B (HHV-6B) did not induce any
cytopathic effect (CPE) or viral antigen expression in either of the cell lines.
Although HHV-6B replication was undetectable, the presence of the HHV-6 genome
in both cell lines was shown by polymerase chain reaction (PCR) during culture
for more than 10 months, suggesting that HHV-6B latently infected SAS413 and
SAS527. Phorbol ester treatment of SAS527 latently infected with HHV-6B resulted
in reactivation of HHV-6, as shown by the appearance of a CPE, positive
reactivity for the HHV-6 antigen, and isolation of infectious HHV-6. These novel
cell lines should be useful for studying the mechanisms of HHV-6-induced
hematopoietic failure and HHV-6 latency and reactivation, as well as
differentiation, of the myeloid cell lineage.

13. Clin Infect Dis 1998 Jan;26(1):132-7 
Persistence of human herpesvirus 6 according to site and variant: possible
greater neurotropism of variant A.
Hall CB, Caserta MT, Schnabel KC, Long C, Epstein LG, Insel RA, Dewhurst S
          Department of Pediatrics, University of Rochester School of
          Medicine and Dentistry, New York 14642, USA.
ab: Little is known of the persistence and pathogenicity of human herpesvirus
6 (HHV-6) after primary infection, including the role of strain variant. Over
2 to 5 years, 2,716 children and 149 families were studied. Peripheral blood
mononuclear cell (PBMC), saliva, and cerebrospinal fluid (CSF) specimens were
examined for HHV-6 DNA and variant. Ninety-nine percent of isolates causing
primary infection were HHV-6 variant B (HHV-6B), which predominated in 95%-98%
of the variants persisting in PBMC and saliva specimens from children and
adults. Of 668 CSF samples, 13% contained HHV-6 DNA; of 77 children examined
after primary infection, 61% had HHV-6 DNA detected only in their CSF and 39%
had HHV-6 DNA in both CSF and PBMCs. HHV-6 variant A (HHV-6A) was detected
significantly (P = .0001) more frequently in CSF than in PBMCs or saliva. In
children for whom HHV-6 was identified in both CSF and PBMCs, PBMCs contained
only HHV-6B, while CSF contained HHV-6A or HHV-6B, not both. Thus, in patients
with dual infection, only HHV-6A persisted in CSF, which suggests that HHV-6A
has greater neurotropism. Findings for adults indicate that dual infection
occurs; variant persistence is similar to that for children. The frequency of
HHV-6A infection increased little with age, thereby indicating that HHV-6A
infection remains uncommon into adulthood. This study suggests that HHV-6
variants have different immunobiologic courses and neurotropism.

14. Secchiero P et al. Detection of human herpesvirus 6 in plasma of children
with primary infection and immunosuppressed patients by polymerase chain
reaction. J Infect Dis 1995 Feb;171(2):273-80.
          Laboratory of Tumor Cell Biology, National Cancer
          Institute, National Institutes of Health, Bethesda,
          Maryland 20892.
ab: A sensitive and specific polymerase chain reaction method for the detection
of human herpesvirus 6 (HHV-6) DNA in serum or plasma has been developed. In
total, 157 human serum or plasma samples were studied. HHV-6 DNA was detected
in 6 (85.7%) of 7 children with exanthem subitum, 3 (23.1%) of 13 bone marrow
transplant (BMT) recipients, 4 (22.2%) of 18 human immunodeficiency virus
(HIV)-infected patients, 1 (2.6%) of 39 patients with chronic fatigue syndrome,
and none of 37 healthy adults. In the HHV-6-positive BMT recipients, HHV-6
plasma DNA was transiently detected during episodes of fever and respiratory
infection. In children with exanthem subitum and in 1 HIV-infected patient, the
HHV-6 strains were characterized as variant B, whereas variant A was detected
in all other patients. Detection of viral DNA in serum or plasma is a marker of
active infection that can be used to investigate the role of HHV-6 in human
disease.

15. He J et al. Infection of primary human fetal astrocytes by human herpesvirus
6. J Virol 1996 Feb;70(2):1296-300.
          Department of Microbiology and Immunology, University of
          Miami School of Medicine, Florida 33101, USA.
ab: Human herpesvirus 6 (HHV-6) is a lymphotropic betaherpesvirus which
productively infects human CD4+ T cells and monocytes. HHV-6 is the etiologic
agent for exanthem subitum (roseola), and it is well-known that central nervous
system complications occur frequently during the course of HHV-6-associated
disease. In addition, HHV-6 has been associated with encephalitis or
encephalopathy. However, very little is known about its tropism for neural
cells. There are reports that HHV-6 may infect some glial cell lines, but
whether it can infect any primary neural cells is not known. Our studies show
that both HHV-6A (GS) and HHV-6B (Z-29) can infect highly purified primary fetal
astrocytes in vitro. Infected cells showed cytopathic effects, forming giant
syncytia. In dual immunofluorescence assays, the infected cells were detected
by antibodies against the HHV-6 p41 nuclear antigen and glial fibrillary acidic
protein, indicating that the infected cells are indeed astrocytes. PCR and
Northern (RNA) blot analyses also confirmed that the astrocytes are infected by
HHV-6. The progeny virus did not alter its host range and could reinfect T cells
as well as primary astrocytes. These findings suggest that infection of primary
human astrocytes may play a role in the neuropathogenesis of HHV-6.

16. Lusso P et al. Infection of natural killer cells by human herpesvirus 6.
Nature 1993 Apr 1;362(6419):458-62 
          Laboratory of Tumor Cell Biology, National Cancer
          Institute, National Institutes of Health, Bethesda,
          Maryland 20892.
ab: Natural killer (NK) cells are a functionally defined subset of non-T, non-B
lymphocytes of bone marrow origin, which induce lysis of selected target cells,
including neoplastic and virus-infected cells. The NK cell function provides an
important mechanism of primary defence against viruses in vivo, as demonstrated
by the occurrence of multiple herpesvirus infections in patients congenitally
lacking NK cells. Here we show that functionally competent CD3- NK clones can
be productively infected by human herpesvirus 6 (HHV-6), a T-lymphotropic DNA
virus that may play a role in the acquired immunodeficiency syndrome (AIDS) and
in the chronic fatigue syndrome, two disorders associated with a defective NK
cell activity. The infection is cytopathic and induces de novo expression of
CD4, an antigen not expressed within the NK lineage, thereby predisposing NK
cells to infection by human immunodeficiency virus type 1 (HIV-1). These results
provide evidence that a herpesvirus can directly target and kill NK cells, a
potential strategy to suppress the natural anti-viral immunity of the host.

17. Wakefield AJ et al. Detection of herpesvirus DNA in the large intestine of
patients with ulcerative colitis and Crohn's disease using the nested polymerase
chain reaction. J Med Virol 1992 Nov;38(3):183-90.
          Inflammatory Bowel Disease Study Group, University College
          and Middlesex School of Medicine, United Kingdom.
ab: The prevalence of herpesvirus DNA was examined in inflammatory bowel disease
tissue. DNA was extracted from resection and biopsy specimens of the large
intestine from patients with ulcerative colitis (n = 21), patients with Crohn's
disease (n = 29), and patients with noninflammatory bowel disease (controls) (n
= 21). The nested polymerase chain reaction was used to detect viral DNA using
primer pairs specific for either cytomegalovirus (CMV), herpes simplex virus 1
(HSV1), human herpesvirus 6 (HHV6), varicella zoster virus (VZV), or Epstein
Barr virus (EBV). HSV1 and VZV DNA were not detected in any of tissue samples.
There was a high prevalence of CMV (81%), HHV6 (76%), and EBV (76%) DNA in
ulcerative colitis tissue compared to Crohn's disease tissues (CMV 66%, HHV6
45%, EBV 55%). Control tissue had a relatively low frequency of CMV (29%) and
EBV (19%) DNA but a prevalence of HHV6 DNA similar to that of ulcerative colitis
(86%). However, the simultaneous presence of HHV6 and CMV and/or EBV DNA in
ulcerative colitis tissue (76%) was much greater than in either Crohn's disease
tissues (38%) or control tissue (29%) (P < 0.05). There was a low prevalence of
CMV, HHV6, and EBV DNA in peripheral blood mononuclear cells from all patient
groups. CMV and EBV are capable of reactivating HHV6: the high prevalence of
coexistent HHV6 infection with either or both of these two viruses in ulcerative
colitis tissue suggests that they may play a synergistic role in the
pathogenesis of this disease.

18. Dewhurst S et al. Phenotypic and genetic polymorphisms among human
herpesvirus-6 isolates from North American infants. Virology 1992
Sep;190(1):490-3.
          Department of Microbiology and Immunology, University of
          Rochester Medical Center, New York 14642.
ab: Fifteen human herpesvirus-6 (HHV-6) isolates from North American infants
with primary infection manifest as febrile or roseola (exanthem subitum) like
illnesses were characterized phenotypically on the basis of their in vitro
growth in continuous T-cell lines and primary human mononuclear cells and by
their reactivity with monoclonal antibodies. All isolates replicated efficiently
in primary human cord blood mononuclear cells, but five distinct patterns of
viral replication in human cells lines were observed. Two of the HHV-6 isolates
from infants were found to replicate in HSB-2 cells, a property associated with
so-called group A viruses, which had previously been isolated only from adults.
These same isolates also reacted with a panel of A-specific monoclonal
antibodies. Genomic characterization of viral isolates using well-characterized
restriction site polymorphisms indicated that these two isolates contained a
mixture of both A- and B-type genomes, in different proportions. These data
suggest that not all HHV-6 isolates can be categorized into one of two broad
groups and that such segregation of HHV-6 isolates may in fact be misleading.

19. Gosselin J et al. Modulatory effects of Epstein-Barr, herpes simplex, and
human herpes-6 viral infections and coinfections on cytokine synthesis. A
comparative study. J Immunol 1992 Jul 1;149(1):181-7. 
          Laboratory of Immunovirology, Faculty of Medicine,
          University of Montreal, Quebec, Canada.
ab: Herpesviruses such as EBV, HSV, and human herpes virus-6 (HHV-6) have a
marked tropism for cells of the immune system and therefore infection by these
viruses may result in alterations of immune functions, leading at times to a
state of immunosuppression. We report the results of a comparative study in
which we found that EBV, HSV-1, and HHV-6 act differentially on the immune
system with regard to their effect on the synthesis of IL-1 beta, IL-6, and
TNF-alpha, i.e., three immunoregulatory cytokines mainly secreted by activated
monocytes/macrophages. Using the polymerase chain reaction technique, analyses
of the mRNA levels for each of the three monokines after viral infection
indicated that the effect exerted by each of these herpesviruses on cytokine
synthesis by human PBMC was detectable at the transcriptional level. Different
amounts of IL-1 beta protein were detected in infected PBMC cultures, HHV-6
being the strongest IL-1 beta up-regulatory among these three herpesviruses.
Spontaneous releases of IL-6 and TNF-alpha were found reduced after infection
by HHV-6 and EBV, respectively. In comparison to EBV and HHV-6, HSV-1 proved to
be a weak monokine enhancer. Results of coinfection studies indicated that
virus-induced suppressive effects on cytokine synthesis are dominant. In fact,
EBV inhibited TNF-alpha synthesis even in the presence of HHV-6, a strong
up-regulator of TNF-alpha synthesis. Similarly, EBV was unable to stimulate IL-6
production in the presence of HHV-6. Viral structural component(s) appeared to
be responsible for the up-regulation of IL-6 by both EBV and HSV-1, and of
TNF-alpha by HSV-1. Taken together, our observations illustrate that
herpesviruses can selectively regulate cytokine synthesis thereby disturbing
immune homeostasis; this effect may favor pathogenic events, including the
reactivation and/or spread of other infectious agents within the host.

20.Gosselin J et al. Infection of peripheral blood mononuclear cells by herpes
simplex and Epstein-Barr viruses. Differential induction of interleukin 6 and
tumor necrosis factor-alpha. J Clin Invest 1992 Jun;89(6):1849-56.
          Laboratory of Immunovirology, Faculty of Medicine,
          University of Montreal, Quebec, Canada.
ab: Infection by herpesviruses can result in profound immunosuppressive or
immunomodulatory effects. However, no significant information is available on
the effect of such infections on the production of immunoregulatory cytokines.
We studied the kinetics of production of two monocyte-derived cytokines,
interleukin 6 (IL-6) and tumor necrosis factor-alpha (TNF alpha), induced by
Epstein-Barr virus (EBV) and herpes simplex virus type 1 (HSV-1) in peripheral
blood mononuclear cell cultures and in fractionated cell populations. We
observed that, when compared to HSV-1, EBV is a stronger inducer of IL-6. In
EBV-infected cultures, IL-6 protein was detected at day 1 postinfection and
gradually increased with time. In contrast, lower amounts of IL-6 were detected
5 d postinfection in HSV-1-infected cultures. HSV-1-infected cultures secreted
significant amounts of TNF alpha protein after 5 d of culture and reached a
maximal level of production at day 7, whereas EBV inhibited TNF alpha
production. In fractionated cell populations, monocytic cells were found to be
the main source of IL-6 synthesis after EBV or HSV-1 infection. However, TNF
alpha synthesis in HSV-1-infected cultures was from both B and monocytic cells.
By using the polymerase chain reaction technique we show that, after infection
by these two herpesviruses, differences in cytokine gene products are also
observed at the transcriptional level. These observations demonstrate that EBV
and HSV-1 exert differential effects on IL-6 and TNF alpha gene transcription
and on the resulting protein secretion in human mononuclear blood cells.

21. Knox KK, Carrigan DR. In vitro suppression of bone marrow progenitor cell
differentiation by human herpesvirus 6 infection. J Infect Dis 1992
May;165(5):925-9.
          Department of Pathology, Medical College of Wisconsin,
          Milwaukee 53226.
ab: Suppression of marrow function may be one of the most serious effects of
human herpesvirus 6 (HHV-6) infection in marrow transplant patients. In this
study, normal bone marrow mononuclear cells were infected in vitro with HHV-6,
and a methylcellulose-based colony formation assay was used to evaluate the
impact of the infection on marrow cell differentiation and proliferation.
Results demonstrated that the outgrowth of colony-forming units of granulocyte
and macrophage lineages (cfu-GM) was decreased by approximately 43%, that growth
of cfu of granulocyte, erythrocyte, macrophage, and megakaryocyte lineages
(cfu-GEMM) was inhibited by an average of 71%, and that the erythroid
burst-forming unit (bfu-E) was decreased by approximately 73%. Further,
outgrowth of the marrow stromal layer was reduced 74%. Direct infection of bone
marrow monocytes was observed, although cell-free virus could not be detected
in infected culture supernatants. Addition of a neutralizing monoclonal antibody
specific for interferon-alpha to the infected cultures resulted in an almost
complete reversal of the viral suppressive effects.

22. Flamand L et al. Human herpesvirus 6 induces interleukin-1 beta and tumor
necrosis factor alpha, but not interleukin-6, in peripheral blood mononuclear
cell cultures. J Virol 1991 Sep;65(9):5105-10.
          Laboratory of Immunovirology, Faculty of Medicine,
          University of Montreal, Quebec, Canada.
ab: The human herpesvirus 6 (HHV-6) is known to interact intimately with cells
of the immune system. Here we report that HHV-6 is a potent inducer of
interleukin-1 beta (IL-1 beta) and tumor necrosis factor alpha (TNF-alpha) in
cultures of peripheral blood mononuclear cells. In contradistinction, HHV-6 has
no effect on IL-6 synthesis. Maximal IL-1 beta and TNF-alpha gene transcription,
as detected by polymerase chain reaction amplification analysis, is observed at
12 and 6 h postinfection, respectively. Release of IL-1 beta and TNF-alpha into
the culture supernatants peaked at 24 h and gradually decreased with time.
Heat-inactivated virus was unable to stimulate IL-1 beta and TNF-alpha
syntheses, whereas UV-irradiated virus retained the full monokine-inducing
potential of the native particle. Preincubation of viral preparation with
neutralizing anti-HHV-6 antibody resulted in the abrogation of this
cytokine-inducing effect, whereas treatment of cells with phosphonoacetic acid
(an inhibitor of viral DNA polymerase activity) had no effect on the ability of
the virus to stimulate monokine release. These results indicate that HHV-6 can
exert a strong immunomodulatory effect by stimulating the cells of myeloid
lineage to produce these cytokines.

23. Lusso P et al. Productive infection of CD4+ and CD8+ mature human T cell
populations and clones by human herpesvirus 6. Transcriptional down-regulation
of CD3. J Immunol 1991 Jul 15;147(2):685-91.
          Laboratory of Tumor Cell Biology, National Cancer
          Institute, National Institute of Allergy and Infectious
          Diseases, Bethesda, MD 20892.
ab: The susceptibility to infection by human herpes-virus 6 (HHV-6) of mature
human T lymphocytes belonging to the two major subpopulations (i.e., CD3+ CD4+
CD8- and CD3+ CD4- CD8+) was investigated by using CD4+ or CD8+ T cell
populations and clones derived from normal adult peripheral blood. Productive
HHV-6 infection was observed in both CD4+ and CD8+ T cells. By days 2 to 6 after
infection, increasing numbers of cells exhibited characteristic morphologic
alterations, becoming enlarged, uniformly rounded and refractile as a
consequence of the virus-induced cytopathic effect. During the course of HHV-6
infection, analysis of the surface membrane phenotype of the T cell populations
and clones revealed a progressive decline in the expression of the CD3/TCR
complex, whereas other T cell-associated markers (e.g., CD2) were unaffected.
Northern blot analysis of mRNA extracted from HHV-6-infected T cells
demonstrated a dramatic loss of the specific messages for the gamma-, delta-,
and epsilon-chains of CD3. Infection by HHV-6, but not by HSV-1 or human CMV,
elicited CD3/TCR down-regulation also in the neoplastic T cell line Jurkat. The
down-regulation of CD3/TCR was dependent upon live virus infection, because
previous inactivation of HHV-6 by heat (56 degrees C for 1 h) or UV light (16
J/m2) totally abrogated the effect. Expression of the immediate early or early
genes of HHV-6 was not sufficient to induce CD3/TCR modulation, as indicated by
studies with the viral DNA polymerase inhibitor phosphonoformic acid. The
observation that both major subsets of mature TCR-alpha beta+ T lymphocytes are
susceptible to HHV-6 infection indicates that this virus may have a broad
spectrum of activity on the immune system. The transcriptional down-regulation
of the CD3/TCR complex, by affecting a critical T cell recognition function,
could be relevant to HHV-6 pathogenesis.

24. Janeway CA et al. Immunobiology..., 4th edition, 1999, Garland Press.

25. Wang FZ et al. Human herpesvirus 6 DNA in cerebrospinal fluid specimens from
allogeneic bone marrow transplant patients: does it have clinical significance?
Clin Infect Dis 1999 Mar;28(3):562-8.
          BMT Program, Huddinge University Hospital, Karolinska
          Institute, Sweden. Fu-Zhang.Wang@smi.ki.se
ab: Cerebrospinal fluid (CSF) specimens from 22 allogeneic bone marrow
transplant patients with central nervous system (CNS) symptoms (cases) and 107
patients who were immunocompromised but did not have CNS symptoms (controls)
were assayed for human herpesvirus 6 (HHV-6) DNA. HHV-6 DNA was detected in CSF
specimens from five (23%) of 22 cases and in CSF specimens from one (0.9%) of
107 controls (P < .001, Fisher's exact test). In addition, none of the five
cases with HHV-6 DNA detected in CSF samples had any other identified cause of
their CNS symptoms, and none of the other 11 cases with known causes for their
CNS diseases had HHV-6 DNA detected in CSF samples (P = .03, Fisher's exact
test). In three cases, HHV-6 variant B was identified, and the HHV-6 variant
could not be defined in the other two cases. Prophylaxis with acyclovir did not
prevent the occurrence of HHV-6-associated CNS disease after allogeneic bone
marrow transplantation. Four cases' conditions were improved or they were cured
after treatment with either ganciclovir or foscarnet, and one case died of CNS
disease despite foscarnet treatment. 

26. Fontan J et al. [Human Herpesvirus 6: general information and infections in
organ transplantations and hematopoietic stem cell grafts]. [Article in French]
Presse Med 1999 Jan 23;28(3):149-56.
          Service d'Hematologie, Centre Hospitalier Universitaire,
          Besancon.
GENERAL DATA: Human herpesvirus 6 (HHV-6) infects 90% of the human population
before the age of 4 years, recognized as a childhood disease (sixth disease) or
with no clinical manifestation. HHV-6 DNA has partial homogly with
cytomegalovirus DNA. Two variants, A and B, are known. The main target cells are
CD4+ T cells and macrophages via a partially elucidated mechanism. Primary
infection is followed by a latency period and episodes of reactivation. Truly
protective targets of the immune response are unknown. POORLY UNDERSTOOD NATURAL
HISTORY: In organ transplant or hematopoietic stem cell recipients, the natural
history of HHV-6 infection is difficult to establish because of small sample
size in certain series, the lack of controls both for patients and samples and
differences in the sensitivity of diagnostic tests. Serology is non-specific and
cannot be used to study reinfection. Different studies have relied on culture
and isolation, detection of viral antigens with monoclonal antibodies and PCR
using mononucleated cells, serum and plasma. PATHOGENICITY: In heart transplant
recipients, HHV-6 infection can cause hepatitis and pancreatic or upper
digestive tract disorders. It has also been suggested that HHV-6 could cause
complications in liver transplant recipients and be involved in rejection
episodes after kidney transplantation. In bone marrow graft recipients, HHV-6
could cause early onset interstitial pneumopathy, myelosuppression phenomena and
aggravated graft versus host reactions. Nevertheless, viral DNA has been found
in certain healthy controls. OTHER POSSIBILITIES: HHV-6 could also be a
co-factor worsening cytomegalovirus infections as has been suggested in liver,
heart and bone marrow recipients. A few cases of HHV-6 encephalitis have been
reported in the literature and would appear to be authentic in transplanted or
grafted subjects. Ganciclovir is effective. However, the practical clinical
impact of HHV-6 infection remains to be established.

27. Yoshida M et al. Comparison of antiviral compounds against human herpesvirus
6 and 7. Antiviral Res 1998 Dec;40(1-2):73-84.
               Department of Virology, Okayama University
               Medical School, Japan.
               mariko@med.okayama-u.ac.jp
ab: Four classes of antiviral compounds were evaluated for inhibitory activity
against two variants of human herpesvirus 6 (HHV-6A and -6B) and human
herpesvirus 7 (HHV-7). These included: 
(1) a pyrophosphate analog, phosphonoformic acid (PFA); 
(2) beta-guanine analogs,
     9-(2-hydroxyethoxymethyl)guanine (acyclovir or ACV),
     9-[(1,3-dihydroxy-2-propoxy)methyl]guanine (ganciclovir or GCV) and
     9-(4-hydroxy-3-hydroxy-3-hydroxymethylbutylyl)guanine (penciclovir or PCV);
(3) acyclic nucleoside phosphonates,
     (S)-1-[(3-hydroxy-2-phosphonylmethoxy)propyl]cytosine [cidofovir or
     (S)-HPMPC] and its cyclic derivative (S)-cyclic-HPMPC (cHPMPC),
     9-[[2-hydroxy-1-phosphonomethoxy)ethoxy]methyl]guanine (HPMEMG) and
     9-[(2-phosphonylmethoxy)ethyl]-2,6-diaminopurine (PMEDAP), 
     and the seven other related compounds; and 
(4) a series of benzimidazole ribonucleosides, including
     2-bromo-5,6-dichloro-1-(beta-D-ribofuranosyl)benzimidazole (BDCRB).
End-point inhibitory concentration (EPC) and 50% effective inhibitory
concentration (EC50) values were determined by a dot-blot antigen detection
method in cord blood mononuclear cells infected with HHV-6A, HHV-6B or HHV-7 at
a multiplicity of infection of 0.004 CCID50/cell. 
**   (S)-HPMPC and cHPMPC had an EC50 value of approximately 0.3 microg/ml for
HHV-6A, 1.2 microg/ml for HHV-6B and 3.0 microg/ml for HHV-7. These compounds
were the most active of those tested against each virus. 
     The EC50 value of GCV for HHV-6A was 0.65 microg/ml, 1.33 microg/ml for
HHV-6B, and >7 microg/ml for HHV-7. 
     The EC50 values of ACV and PCV were approximately 6-8 microg/ml for HHV-6A,
16-24 microg/ml for HHV-6B and 121-128 microg/ml for HHV-7. These drugs were the
least active. The sensitivity of HHV-7 to the guanine analogs was different from
HHV-6, suggesting a difference in selectivity of specific viral enzymes.
PMID: 9864048, UI: 99079752

28. Lau YL et al. Primary human herpes virus 6 infection transmitted from donor
to recipient through bone marrow infusion. Bone Marrow Transplant 1998
May;21(10):1063-6.
          Department of Paediatrics, The University of Hong Kong,
          Queen Mary Hospital, Pokfulam.
ab: An 8.5-month-old boy with Wiskott-Aldrich syndrome received a sibling
matched bone marrow transplant from his healthy non-identical twin brother. The
donor had primary human herpes virus 6 (HHV-6) infection around the time of bone
marrow donation. The recipient had hepatitis in the first week and then
developed fever and rash on day 18. Skin biopsy was shown to have HHV-6 antigen
and his peripheral blood leukocytes were HHV-6 DNA positive. He engrafted on day
18 but the ANC dropped from 5.5 x 10(9)/l (day 23) to 0.48 x 10(9)/l (day 34)
with persistent HHV-6 DNAemia. Bone marrow on day 35 was positive for HHV-6 DNA.
He was treated with G-CSF and ganciclovir with good response. He later had
pneumonitis which was treated empirically with foscarnet, ceftazidime and
clarithromycin.

29. Rieux C et al. Human herpesvirus-6 meningoencephalitis in a recipient of an
unrelated allogeneic bone marrow transplantation. Transplantation 1998 May
27;65(10):1408-11.
          Service d'Hematologie, Hopital Henri Mondor, Creteil,
          France.
BACKGROUND: Human herpesvirus-6 (HHV-6) has been implicated in bone marrow
suppression, interstitial pneumonitis, and fatal meningoencephalitis in bone
marrow transplant (BMT) recipients. METHODS: We describe the case of a woman
with acute myeloid leukemia in second remission who developed febrile
meningoencephalitis 8 months after a second unrelated BMT. RESULTS: Computed
tomography and magnetic resonance images of the brain were nonspecific. Analysis
of cerebrospinal fluid (CSF) revealed lymphocytosis and an increased protein
level. Using polymerase chain reaction methods, HHV-6 was the only pathogen
detected in CSF, peripheral blood mononuclear cells, and bone marrow. The
patient was treated with ganciclovir and foscarnet for 3 months. All clinical
manifestations resolved and HHV-6 polymerase chain reaction analysis of CSF
became negative 40 days after the beginning of antiviral treatment.
CONCLUSIONS: This observation strongly suggests that HHV-6 should be sought in
BMT patients with neurological complications and that HHV-6 meningoencephalitis
may respond to ganciclovir and foscarnet therapy.

30. Takahashi K. [Recent advances in antiviral drugs--antiviral agents to HCMV,
HHV-6, and HHV-7]. [Article in Japanese] Nippon Rinsho 1998 Jan;56(1):140-4.
          Department of Microbiology, Fukushima Medical College.
ab: Foscarnet, Phosphonoformate, has recently approved for the treatment of HCMV
retinitis in AIDS patients in Japan. It inhibits the viral DNA polymerase and
effective against ganciclovir-resistant HCMV. Cidofovir,
(S)-1-[3-hydroxy-2-(phosphonylmethoxy)propyl]cytosine, a new acyclic nucleotide
phosphonate analogues has potent activity against HCMV retinitis in AIDS at
3-7.5 mg/kg/week, once/week with concomitant oral probenecid and saline
prehydration to prevent nephrotoxicity. The highest potency and selectivity
against HHV-6 and HHV-7 was demonstrated S2242 (N7-isomer of
6-deoxy-ganciclovir). Ganciclovir, foscarnet, and cidofovir also exhibited
selective inhibitory activity to these viruses, although the activities were not
so remarkable compared with in case of HCMV. Thymidine kinase-dependent drugs
(acyclovir, brivudin) showed little, if any, activity. These results suggest a
structural homology of the DNA polymerase and a lack of TK gene among these
three beta-herpesviruses.

31. Okamoto T et al. Successful treatment of severe cytomegalovirus retinitis
with foscarnet and intraocular injection of ganciclovir in a myelosuppressed
unrelated bone marrow transplant patient. Bone Marrow Transplant 1997
Nov;20(9):801-3.
          Second Department of Internal Medicine, Hyogo College of
          Medicine, Nishinomiya, Japan.
ab: A female patient with ALL received a bone marrow transplant (BMT) from an
unrelated donor with a one locus HLA mismatch. The donor was heterozygous at the
HLA-A locus, while the patient was homozygous at this locus. The patient had
cytomegalovirus (CMV) antigenemia on day 42 following an intensive preparative
regimen that included anti-thymocyte globulin and BU+CY+TBI to prevent graft
rejection. Ganciclovir was given initially for the treatment of CMV antigenemia,
although the patient soon developed severe myelosuppression. The patient's
hematopoietic recovery was poor, and CMV and human herpesvirus-6 (HHV-6) were
detectable in the peripheral blood. Severe CMV retinitis was treated with
foscarnet and the intraocular injection of ganciclovir. The CMV retinitis
improved and the marrow gradually recovered. CMV and HHV-6 were no longer
detectable in the peripheral blood. Foscarnet and intraocular injection of
ganciclovir appeared to be an effective treatment for CMV retinitis in this
myelosuppressed BMT patient.

32. Citations can be found on two autism-related webpages:

33. Gupta S, Vayuvegula B. A comprehensive immunological analysis in chronic
fatigue syndrome. Scand J Immunol 1991 Mar;33(3):319-27. 
          Division of Basic and Clinical Immunology, University of
          California, Irvine 92717.
ab: A detailed analysis of cell-mediated and antibody-mediated immunity was
performed in 20 CDC-defined patients with chronic fatigue syndrome (CFS) and 20
age- and sex-matched healthy controls. CD3+, CD4+, CD8+, and CD20+ lymphocytes
were comparable in two groups. Natural killer cells as defined by CD16, CD56 and
CD57 antigens were significantly reduced in CFS. A significant increase in the
proportions of CD4+ ICAM 1+ T cells was observed in CFS. Monocytes from CFS
displayed increased density (as determined by mean fluorescence channel numbers)
of intercellular adhesion molecule 1 (ICAM-1) and lymphocyte function associated
antigen 1 (LFA-1), but showed decreased enhancing response to recombinant
interferon-gamma in vitro. The lymphocyte DNA synthesis in response to
phytohaemoglobulin (PHA), Concanavalin A (Con A) and pokeweed mitogen (PWM) was
normal but the response to soluble antigens was significantly reduced. Serum
IgM, IgG, IgA, and IgG subclasses were normal. In vivo specific antibody
response to pneumococcus vaccine was depressed in CFS. Forty percent of patients
showed titres of anti-human herpes virus 6 (anti-HHV-6) antibody higher than
that in the controls (greater than or equal to 1/80). These data suggest
immunological dysfunction in patients with chronic fatigue syndrome. The
significance of these observations is discussed.

34. Newcombe DS. Immune surveillance, organophosphorus exposure, and
lymphomagenesis. Lancet 1992 Feb 29;339(8792):539-41.
          Department of Environmental Health Sciences, Johns Hopkins
          University School of Hygiene and Public Health, Baltimore,
          Maryland 21205.
ab: Prevalence of lymphoproliferative disorders is increased in populations with
various chemical exposures, including organophosphorus compounds. Lymphomas are
also more common in individuals with a substantially decreased monocyte esterase
activity. Organophosphorus compounds inhibit esterases associated with
monocytes, natural killer (NK) cells, lymphokine-activated killer (LAK) cells,
and cytotoxic T lymphocytes, and these inhibitory effects impair immune
surveillance and cytotoxic functions mediated by such cells. Lymphoma
development is also associated with Epstein-Barr virus (EBV) and human
herpesvirus-6 (HHV-6) infections, which are regulated by cytotoxic immune
responses mediated by monocytes, T cells, and NK cells. My hypothesis is that
lymphomagenesis is a multistep process, and the absence or inhibition of
monocyte esterase and perhaps other immune cell esterases alters
esterase-dependent detoxification of a factor critical for the early steps of
oncogenesis. Also, such an enzyme deficit might impair the processes that
regulate the dissemination and limit the total burden of pathogens such as the
lymphoma-associated herpesviruses. An added risk to any viral-mediated
lymphoproliferation might be an organophosphorus-induced oncogenic genetic
change.