Dynamic acquisition of HTLV-1 tax protein by mononuclear phagocytes: Role in neurologic disease.

Pathology of HTLV-1 associated myelopathy/Tropical spastic paraparesis (HAM/TSP) is believed to be the result of "bystander damage" involving effector CD8 (+) T lymphocytes (CTLs) killing of virus infected cells. But the specific cellular events leading up to tissue injury are still unclear. Here, we developed the Microscopy Imaging of Cytotoxic T lymphocyte assay with Fluorescence emission (MI-CaFé), an optimized visualization analysis to explore the interactions between CTLs and virus infected or viral antigen presenting target cells. Various cell-to-cell formations can be observed and our results demonstrate elevated frequencies of CTL-target cell conjugates in HAM/TSP patient PBMCs compared to control PBMCs. Furthermore, HTLV-1 Tax protein expression can be localized at the cell-cell junctions and also tracked moving from an infected cell to a CD14 (+) mononuclear phagocyte (MP). Activation of CD14 (+) MPs in HAM/TSP patient PBMCs and antigenic presentation of HTLV-1 Tax by MPs can be inferred by their spontaneous cytotoxicity after 18h of in vitro culture. Given that CD4 (+) T lymphocytes are the primary reservoirs of HTLV-1 and MPs are scavenger cells responsible for pathogen clearance, spontaneous cytotoxicity against MPs in HAM/TSP PBMCs suggests a mechanism of chronic inflammation, secondary to low level of persistent virus infection within the central nervous system.

Myelin basic protein-specific TCR/HLA-DRB5*01:01 transgenic mice support the etiologic role of DRB5*01:01 in multiple sclerosis.

Genetic susceptibility to multiple sclerosis (MS) has been linked to the HLA-DR15 haplotype consisting of DRB1*15:01(DR2b) and DRB5*01:01(DR2a) alleles. Given almost complete linkage disequilibrium of the two alleles, recent studies suggested differential roles in susceptibility (DR2b) or protection from MS (DR2a). Our objective was to assess the potential contribution of DR2a to disease etiology in MS using a humanized model of autoimmunity. To assess the potential contribution of DR2a to disease etiology, we created DR2a humanized transgenic (Tg) mice and subsequently crossed them to Tg mice expressing TL3A6, an MS patient-derived myelin basic protein 83-99-specific TCR. In TL3A6/DR2a Tg mice, CD4 Tg T cells escape thymic and peripheral deletion and initiate spontaneous experimental autoimmune encephalomyelitis (EAE) at low rates, depending on the level of DR2a expression. The ability to induce active EAE was also increased in animals expressing higher levels of DR2a. Inflammatory infiltrates and neuronal damage were present throughout the spinal cord, consistent with a classical ascending EAE phenotype with minor involvement of the cerebellum, brainstem, and peripheral nerve roots in spontaneous, as well as actively induced, disease. These studies emphasize the pathologic contribution of the DR2a allele to the development of autoimmunity when expressed as the sole MHC class II molecule, as well as strongly argue for DR2a as a contributor to the CNS autoimmunity in MS.

Human herpesvirus-6 entry into the central nervous system through the olfactory pathway.

Viruses have been implicated in the development of neurodegenerative diseases, such as Alzheimer's, Parkinson's, and multiple sclerosis. Human herpesvirus-6 (HHV-6) is a neurotropic virus that has been associated with a wide variety of neurologic disorders, including encephalitis, mesial temporal lobe epilepsy, and multiple sclerosis. Currently, the route of HHV-6 entry into the CNS is unknown. Using autopsy specimens, we found that the frequency of HHV-6 DNA in the olfactory bulb/tract region was among the highest in the brain regions examined. Given this finding, we investigated whether HHV-6 may infect the CNS via the olfactory pathway. HHV-6 DNA was detected in a total of 52 of 126 (41.3%) nasal mucous samples, showing the nasal cavity is a reservoir for HHV-6. Furthermore, specialized olfactory-ensheathing glial cells located in the nasal cavity were demonstrated to support HHV-6 replication in vitro. Collectively, these results support HHV-6 utilization of the olfactory pathway as a route of entry into the CNS.

Mechanism of neuroinflammation: enhanced cytotoxicity and IL-17 production via CD46 binding.

The membrane co-factor protein CD46 is the cellular receptor for a number of pathogens including the human herpesvirus 6 (HHV-6). In addition to its function as an inhibitory complement receptor, engagement of CD46 in the context of T-cell receptor (TCR) signaling influences T-cell activation. Simultaneous cross-linking of the CD3/CD46 molecules led to differentiation of a unique population of CD4+ T-cell subset characterized by enhanced expressions of IFN-gamma, IL-10, granzyme B, adhesion molecule MAdCAM-1 (alpha-4-beta-7), surface-bound cytokine LIGHT, and chemokine receptor CCR9. Multiple sclerosis is a chronic inflammatory neurodegenerative disorder of the central nervous system (CNS) with unknown etiology. The HHV-6 is a candidate pathogen in MS and uses the CD46 molecule as its receptor. We hypothesize that binding of the HHV-6 glycoprotein to CD46 may trigger a pro-inflammatory response that could contribute to CNS tissue damage. To address this question, we examined immunological parameters such as proliferation, cytokine production and cytotoxic functions in CD4+ T cells of healthy individuals and MS patients following CD3/CD46 co-engagement by using anti-CD3 and anti-CD46 monoclonal antibodies as surrogates to mimic T-cell receptor and CD46 signaling. Our results demonstrated that CD3/CD46 cross-linking induced expression of IL-1beta and IL-17A in multiple sclerosis patient T cells. Additionally, increase in transient surface expression of lysosomal associated protein CD107a suggested enhanced CD4+ T-cell cytotoxic functions following CD3/CD46 co-stimulation. Collectively, this study demonstrated evidence to suggest a potential mechanism of virus-induced neuroinflammation that may be involved in MS disease pathogenesis.

Detection of human herpesvirus-6 variants in pediatric brain tumors: association of viral antigen in low grade gliomas.

BACKGROUND: Human herpesvirus-6 (HHV-6) has been associated with a diverse spectrum of central nervous system (CNS) diseases and reported glial tropism. OBJECTIVE: To determine if HHV-6 is present in a series of pediatric brain tumors. STUDY DESIGN: Pediatric gliomas from 88 untreated patients represented in a tissue microarray (TMA) were screened for HHV-6 by nested polymerase chain reaction (PCR), in situ hybridization (ISH), and immunohistochemistry (IHC) and compared to non-glial tumors (N=22) and control brain (N=32). Results were correlated with tumor grade and overall survival. RESULTS: HHV-6 U57 was detected by nested PCR in 68/120 (57%) tumors and 7/32 (22%) age-matched non-tumor brain (P=0.001). HHV-6 U31 was positive in 73/120 (61%) tumors and 11/32 (34%) controls (P=0.019). Seventy-two percent (43/60) of tumors were HHV-6 Variant A. HHV-6 U57 was confirmed by ISH in 83/150 (54%) tumors and 10/32 (31%) controls (P=0.021), revealing a non-lymphocytic origin of HHV-6. HHV-6A/B gp116/64/54 late antigen was detected by IHC in 50/124 (40%) tumors and 6/32 (18%) controls (P=0.013). Interestingly, 58% of low grade gliomas (N=67) were IHC positive compared to 19% of high grade gliomas (N=21, P=0.002) and 25% of non-gliomas (N=36, P=0.001). HHV-6A/B gp116/64/54 antigen co-localized with glial fibrillary acidic protein, confirming the astrocytic origin of antigen. Overall, there was no primary association between HHV-6A/B gp116/64/54 antigen detection and survival (P=0.861). CONCLUSIONS: We provide the first reported series of HHV-6 detection in pediatric brain tumors. The predominance of HHV-6 in glial tumors warrants further investigation into potential neurooncologic disease mechanisms.

Effect of (r)-9-[4-hydroxy-2-(hydroxymethyl)butyl]guanine (H2G) and AZT-lipid-PFA on human herpesvirus-6B infected cells.

BACKGROUND: Human herpesvirus-6 (HHV-6) has been associated with a wide spectrum of diseases. (r)-9-[4-Hydroxy-2-(hydroxymethyl)butyl]guanine (H2G) is an acyclic guanosine analogue that is structurally similar to acyclovir and is in clinical development for treatment of herpesvirus infections. H2G has been found to have activity against HSV type 1, HSV type 2, and HHV-6 in lymphoblast cell lines. A new anti-viral duplex drug, 3'-azido-3'-deoxythymidylyl-(5'-->2-O)-3-O-octadecyl-sn-glycerol (AZT-lipid-PFA), linking zidovudine (AZT) and foscarnet (PFA) via a lipophilic octadecylglycerol residue (lipid) also exhibits anti-viral activities against HIV, HSV type 1 and HCMV. OBJECTIVE: To assess the efficacy of H2G and AZT-lipid-PFA conjugate against HHV-6. STUDY DESIGN: Drug-associated toxicity and proliferative response were evaluated. We conducted in vitro experiments to determine the efficacy of H2G and an AZT-lipid-PFA conjugate in interfering with expression HHV-6 viral transcript in primary human peripheral blood mononuclear cells (PBMC). RESULTS: Both H2G and AZT-lipid-PFA were effective at inhibiting expression of HHV-6 gene transcript at comparable concentrations. Additionally, while AZT-lipid-PFA treatment was toxic to cells at concentrations above 5microM, H2G treatment was associated with minimal cytotoxicity. CONCLUSION: These data suggest the potential application of these anti-viral compounds in controlling HHV-6 infection.

Detection of human herpesvirus-6 in cerebrospinal fluid of patients with encephalitis.

OBJECTIVE: Virus infections are the most common causes of encephalitis, a syndrome characterized by acute inflammation of the brain. More than 150 different viruses have been implicated in the pathogenesis of encephalitis; however, because of limitations with diagnostic testing, causative factors of more than half of the cases remain unknown. METHODS: To investigate whether human herpesvirus-6 (HHV-6) is a causative agent of encephalitis, we examined for evidence of virus infection by determining the presence of viral sequence using polymerase chain reaction and assessed HHV-6 antibody reactivity in the cerebrospinal fluid of encephalitis patients with unknown cause. In a cohort study, we compared virus-specific antibody levels in cerebrospinal fluid samples of patients with encephalitis, relapsing-remitting multiple sclerosis, and other neurological diseases. RESULTS: Our results demonstrated increased levels of HHV-6 IgG, as well as IgM levels, in a subset of encephalitis patients compared with other neurological diseases. Moreover, cell-free viral DNA that is indicative of active infection was detected in 40% (14/35) of encephalitis patients, whereas no amplifiable viral sequence was found in either relapsing-remitting MS or other neurological diseases patients. In addition, a significant correlation between polymerase chain reaction detection and anti-HHV-6 antibody response was also demonstrated. INTERPRETATION: Collectively, these results suggested HHV-6 as a possible pathogen in a subset of encephalitis cases.

Different development of myelin basic protein agonist- and antagonist-specific human TCR transgenic T cells in the thymus and periphery.

Myelin basic protein (MBP)-specific T cells are thought to play a role in the development of multiple sclerosis. MBP residues 111-129 compose an immunodominant epitope cluster restricted by HLA-DRB1*0401. The sequence of residues 111-129 of MBP (MBP(111-129)) differs in humans (MBP122:Arg) and mice (MBP122:Lys) at aa 122. We previously found that approximately 50% of human MBP(111-129) (MBP122:Arg)-specific T cell clones, including MS2-3C8 can proliferate in response to mouse MBP(111-129) (MBP122:Lys). However, the other half of T cell clones, including HD4-1C2, cannot proliferate in response to MBP(111-129) (MBP122:Lys). We found that MBP(111-129) (MBP122:Lys) is an antagonist for HD4-1C2 TCR, therefore, MS2-3C8 and HD4-1C2 TCRs are agonist- and antagonist-specific TCRs in mice, respectively. Therefore, we examined the development of HD4-1C2 TCR and MS2-3C8 TCR transgenic (Tg) T cells in the thymus and periphery. We found that dual TCR expression exclusively facilitates the development of MBP(111-129) TCR Tg T cells in the periphery of HD4-1C2 TCR/HLA-DRB1*0401 Tg mice although it is not required for their development in the thymus. We also found that MS2-3C8 TCR Tg CD8(+) T cells develop along with MS2-3C8 TCR Tg CD4(+) T cells, and that dual TCR expression was crucial for the development of MS2-3C8 TCR Tg CD4(+) and CD8(+) T cells in the thymus and periphery, respectively. These results suggest that thymic and peripheral development of MBP-specific T cells are different; however, dual TCR expression can facilitate their development.

Anti-HTLV antibody profiling reveals an antibody signature for HTLV-I-associated myelopathy/tropical spastic paraparesis (HAM/TSP).

BACKGROUND: HTLV-I is the causal agent of adult T cell leukemia (ATLL) and HTLV-I-associated myelopathy/tropical spastic paraparesis (HAM/TSP). Biomarkers are needed to diagnose and/or predict patients who are at risk for HAM/TSP or ATLL. Therefore, we investigated using luciferase immunoprecipitation technology (LIPS) antibody responses to seven HTLV-I proteins in non-infected controls, asymptomatic HTLV-I-carriers, ATLL and HAM/TSP sera samples. Antibody profiles were correlated with viral load and examined in longitudinal samples. RESULTS: Anti-GAG antibody titers detected by LIPS differentiated HTLV-infected subjects from uninfected controls with 100% sensitivity and 100% specificity, but did not differ between HTLV-I infected subgroups. However, anti-Env antibody titers were over 4-fold higher in HAM/TSP compared to both asymptomatic HTLV-I (P < 0.0001) and ATLL patients (P < 0.0005). Anti-Env antibody titers above 100,000 LU had 75% positive predictive value and 79% negative predictive value for identifying the HAM/TSP sub-type. Anti-Tax antibody titers were also higher (P < 0.0005) in the HAM/TSP compared to the asymptomatic HTLV-I carriers. Proviral load correlated with anti-Env antibodies in asymptomatic carriers (R = 0.76), but not in HAM/TSP. CONCLUSION: These studies indicate that anti-HTLV-I antibody responses detected by LIPS are useful for diagnosis and suggest that elevated anti-Env antibodies are a common feature found in HAM/TSP patients.

Reactivation of human herpesvirus-6 in natalizumab treated multiple sclerosis patients.

The alpha(4) integrin antagonist natalizumab was shown to be effective in patients with immune-mediated disorders but was unexpectedly associated with JC polyomavirus associated progressive multifocal leukoencephalopathy (PML) in two multiple sclerosis (MS) and one Crohn's disease patients. Impaired immune surveillance due to natalizumab treatment may have contributed to the JCV reactivation. As HHV-6 has been suggested to play a role in MS, we asked whether this virus could also have been reactivated during natalizumab therapy. Matched sera and CSF from a limited set of MS patients treated with and without natalizumab were examined for evidence of HHV-6. In addition, we also superinfected a persistent JC virus infected glial cell with HHV-6A to determine if JC virus can be increased. Elevated serum HHV6 IgG and HHV-6A DNA was detected in the CSF of a subset of patients but not controls. We confirmed that superinfection with HHV-6 of a JC virus infected glial cells increased expression of JCV. These results support the hypothesis that treatment with natalizumab may be associated with reduced immune surveillance resulting in reactivation of viruses associated with MS pathogenesis.

Dysregulation of TGF-beta signaling and regulatory and effector T-cell function in virus-induced neuroinflammatory disease.

We previously demonstrated that CD4(+)CD25(+) T regulatory cells (Tregs), important for the maintenance of immune tolerance and prevention of autoimmune disease, from patients with human T lymphotropic virus type I (HTLV-I)-associated myelopathy/tropical spastic paraparesis (HAM/TSP) exhibit reduced Foxp3 expression and Treg suppressor function compared with healthy donors. Since TGF-beta signaling has been previously reported to be critical for both Foxp3 expression and Treg function, we examined whether this signaling pathway was dysregulated in patients with HAM/TSP. Levels of TGF-beta receptor II (TGF-betaRII) as well as Smad7 (a TGF-beta-inducible gene) were significantly reduced in CD4(+) T cells in patients with HAM/TSP compared with healthy donors, and the expression of TGF-betaRII inversely correlated with the HTLV-I tax proviral load. Importantly, both CD4(+)CD25(+) and CD4(+)CD25(-) T cells from HAM/TSP patients exhibited reduced TGF-betaRII expression compared with healthy donors, which was associated with functional deficits in vitro, including a block in TGF-beta-inducible Foxp3 expression that inversely correlated with the HTLV-I tax proviral load, loss of Treg suppressor function, and escape of effector T cells from Treg-mediated control. This evidence suggests that a virus-induced breakdown of immune tolerance affecting both regulatory and effector T cells contributes to the pathogenesis of HAM/TSP.

The effect of interferon-beta on black holes in patients with multiple sclerosis.

Multiple sclerosis (MS) is an immunological disorder of the CNS. Linked to an initial transient inflammation as the result of blood-brain barrier leakage, the disease progresses into a neurodegenerative phase. MRI is the most powerful paraclinical tool for diagnosing and monitoring MS. Although contrast enhancing lesions are the visible events of blood-brain barrier breakdown, accumulation of hypointense lesions, namely black holes, are recognised as irreversible axonal loss. IFN-beta is administered as a first-line drug in MS patients. However, whether the effect of IFN-beta extends beyond just prevention of blood-brain barrier leakage and further prevents the formation of black holes or promotes their recovery once formed, is not yet understood.

GLUT1 is not the primary binding receptor but is associated with cell-to-cell transmission of human T-cell leukemia virus type 1.

GLUT1 has recently been suggested to be a binding receptor for human T-cell leukemia virus type 1 (HTLV-1). We used a novel, short-term assay to define the role of GLUT1 in cell-to-cell transmission. Although increasing cell surface levels of GLUT1 enhanced HTLV-I transfer, efficient virus spread correlated largely with heparan sulfate proteoglycan (HSPG) expression on target cells. Moreover, since activated CD4+ T cells and cord blood lymphocytes that are susceptible to HTLV-1 infection expressed undetectable levels of surface GLUT1, these results indicate that GLUT1 and HSPGs are important for efficient cell-to-cell transmission of HTLV-1 but raise concerns on the role of GLUT1 as the HTLV-1 primary binding receptor.

Efficacy of antiviral compounds in human herpesvirus-6-infected glial cells.

The beta-herpesvirus human herpesvirus-6 (HHV-6) is becoming increasingly recognized as an important pathogen in immunocompromised patients, particularly in post bone marrow transplant (BMT). Reactivation of latent HHV-6 resulting in encephalitis has been reported in BMT and stem cell transplant (SCT) patients. The development of HHV-6 encephalitis can be a fatal complication, the frequency of which is increasing likely due to improved diagnosis with quantitative polymerase chain reaction (PCR) of cerebrospinal fluid. There are currently no antiviral compounds approved for HHV-6, nor have any controlled clinical trials been conducted. The frequency and severity of HHV-6 encephalitis in both immunocompetent and immunocompromised patients necessitates studies on the usefulness of currently available anti-viral compounds. The authors compared the antiviral efficacy of four drugs currently used for cytomegalovirus (CMV) infection, a beta-herpesvirus sharing homology with HHV-6. In HHV-6A- and HHV-6B-infected T cells, acyclovir, ganciclovir, foscarnet, and cidofovir exhibited antiviral activity consistent with that published in other studies. In HHV-6-infected human astrocytes (U251), however, only foscarnet and cidofovir exhibited antiviral activity and this effect was restricted to infection with HHV-6 variant A. In pathological brain sections from patients with neurological disorders such as multiple sclerosis and epilepsy, HHV-6 has been localized to glial cells. Determination of antiviral activity in human glial fibrillary acidic protein (GFAP)-positive astrocytes of currently used antiviral compounds is essential for potential treatment of HHV-6 and neurological disorders. Our data highlight the necessity for further study of antiviral compound in HHV-6-infected glial cells as well as the development of more selective compounds for HHV-6.

Memory lineage relationships in HTLV-1-specific CD8+ cytotoxic T cells.

Cytotoxic memory T cells play a critical role in combating viral infections; however, in some diseases they may contribute to tissue damage. In HAM/TSP, HTLV-1 Tax 11-19+ cells proliferate spontaneously in vitro and can be tracked using the Tax 11-19 MHC Class I tetramer. Immediately ex vivo, these cells were a mix of CD45RA-/CCR7- TEM and CD45RA+/CCR7- TDiff memory CTL. The subsequent proliferating Tax 11-19 tetramer+ population expressed low levels of IL-7Ralpha, failed to respond to IL-7 and IL-15, and did not develop a TCM phenotype. Thus, chronic exposure to viral antigen may result in a sustained pool of TEM cells that home to the CNS and mediate the spinal cord pathology seen in this disease.

Foxp3 represses retroviral transcription by targeting both NF-kappaB and CREB pathways.

Forkhead box (Fox)/winged-helix transcription factors regulate multiple aspects of immune responsiveness and Foxp3 is recognized as an essential functional marker of regulatory T cells. Herein we describe downstream signaling pathways targeted by Foxp3 that may negatively impact retroviral pathogenesis. Overexpression of Foxp3 in HEK 293T and purified CD4+ T cells resulted in a dose-dependent and time-dependent decrease in basal levels of nuclear factor-kappaB (NF-kappaB) activation. Deletion of the carboxyl-terminal forkhead (FKH) domain, critical for nuclear localization and DNA-binding activity, abrogated the ability of Foxp3 to suppress NF-kappaB activity in HEK 293T cells, but not in Jurkat or primary human CD4+ T cells. We further demonstrate that Foxp3 suppressed the transcription of two human retroviral promoters (HIV-1 and human T cell lymphotropic virus type I [HTLV-I]) utilizing NF-kappaB-dependent and NF-kappaB-independent mechanisms. Examination of the latter identified the cAMP-responsive element binding protein (CREB) pathway as a target of Foxp3. Finally, comparison of the percent Foxp3+CD4+CD25+ T cells to the HTLV-I proviral load in HTLV-I-infected asymptomatic carriers and patients with HTLV-I-associated myelopathy/tropical spastic paraparesis suggested that high Foxp3 expression is associated with low proviral load and absence of disease. These results suggest an expanded role for Foxp3 in regulating NF-kappaB- and CREB-dependent cellular and viral gene expression.

Differential HHV-6A gene expression in T cells and primary human astrocytes based on multi-virus array analysis.

Human herpesvirus 6 (HHV-6) is a ubiquitous virus that has been associated with a wide spectrum of diseases, such as exanthem infantum, multiple sclerosis, seizures, encephalitis/meningitis, and more recently, mesial temporal lobe sclerosis. Although HHV-6 is known to predominately infect CD4+ T lymphocytes, its ability to infect neural glial cells has been demonstrated both in vitro and in vivo. Reactivation of latent HHV-6 infection in the brain has recently been suggested to play a role in the development of neuropathogenesis. To investigate the association of viral gene expression and disease pathogenesis, we developed a multi-virus array containing all open reading frames of the HHV-6 virus and other pathogenically related viruses (EBV, HBV, HHV-8, HIV-1, HTLV-1, HTLV-2) to study expression of viral gene transcripts. In this study, we infected CD4+ T lymphocytes and primary human astrocytes derived from brain biopsy material in vitro with the more neurotropic HHV-6A strain. Hierarchal cluster analysis based on gene expression over time suggested a temporally regulated herpesvirus transcription process. Furthermore, we compared viral gene expression in CD4+ T lymphocytes and primary human astrocytes at peak viral load levels (>10(8) copies of virus/10(6) cells) at 5 days post-infection. Differential expression of HHV-6A genes was observed between CD4+ T lymphocytes and primary human astrocytes. Absence of a number of HHV-6 genes detected at 5 days post-infection in primary human astrocytes suggests an alternative replication strategy used by HHV-6 to evade immune detection and allow establishment of persistent infection in neural glial cells.

Human T lymphotropic virus types I and II western blot seroindeterminate status and its association with exposure to prototype HTLV-I.

Human T lymphotropic virus types I and II (HTLV-I/II) Western blot (WB) seroindeterminate status, which is defined as an incomplete banding pattern of HTLV protein Gag (p19 or p24) or Env (GD21 or rgp46), is commonly observed. To investigate the significance of this finding, we examined HTLV-I/II serostatus and HTLV-I proviral load in 2 groups of individuals with WB seroindeterminate status. Low proviral loads were detected in 42% of patients with neurologic symptoms and 44% of voluntary blood donors. These data suggest that a subset of WB seroindeterminate individuals may be infected with prototype HTLV-I. To confirm this hypothesis, we evaluated HTLV-I/II serostatus and proviral load in prospectively collected specimens from 66 WB seronegative patients who had received HTLV-I-infected blood products by transfusion. Eight individuals developed WB seroindeterminate profiles after the transfusion. In addition, using a human leukocyte antigen type A*201-restricted HTLV-I Tax11-19 tetramer, we detected virus-specific CD8(+) T cells in peripheral blood mononuclear cells from WB seroindeterminate patients. These CD8(+) T cells were effective at targeting HTLV-I-infected cells. Collectively, the results suggest that HTLV-I/II WB seroindeterminate status may reflect a history of HTLV-I exposure. Our findings warrant further investigation of the possible clinical outcomes associated with WB seroindeterminate status.

Detection of HHV-6B in post-mortem central nervous system tissue of a post-bone marrow transplant recipient: a multi-virus array analysis.

BACKGROUND: HHV-6 has been implicated in a number of neurological disorders. Recent evidence has suggested high incidence of HHV-6 infection in patients (46%) undergoing allogeneic bone marrow transplant (BMT). OBJECTIVE: To investigate whether HHV-6 plays a role in the development of fatal encephalopathy in an allogeneic post-BMT patient using an unbiased approach. RESULTS: Detection of HHV-6 viral DNA sequence and RNA expression were demonstrated in fresh frozen post-mortem autopsy material derived from the insular cortex using a multi-virus array platform. In addition, PCR analysis by real-time quantitative TaqMan demonstrated high viral burden in multiple brain regions tested. Sequencing analysis of PCR product confirmed the virus to be HHV-6 variant B. CONCLUSIONS: Active infection as demonstrated by expression of viral RNA and high viral load in the CNS suggest a possible pathogenic role of HHV-6 in development neurologic complications post-BMT.