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Recent studies have brought renewed interest to the hypothesis that infection plays a role in the pathogenesis of Alzheimer’s disease (AD). In particular, herpesviruses such as herpes simplex virus-1 (HSV-1) and human herpesvirus-6 (HHV-6) have had an extensive history of association with AD. The interplay between viral infection and a variety of neurological diseases has long been an area of interest but proving causality has been elusive. Two recent studies, Readhead et al. (2018) and Eimer et al. (2018) have again renewed the debate concerning the role of pathogens (herpesviruses) in AD. In this review, we will briefly discuss the literature in support of a herpesvirus role in AD pathogenesis and try to bridge two main observations in AD research; the ability of Aβ to aggregate with pathogens, and the detection of herpesviruses in AD brain material compared to non-AD controls. While the data linking AD and human herpesviruses suggest that these pathogens may contribute to disease progression, further work is needed to determine the significance of these observations, if any, to the etiology of the disease.

Infection with Human Herpesvirus-6 (HHV-6) has been associated with different epilepsy syndromes, including febrile seizures and status epilepticus, acute symptomatic seizures secondary to encephalitis and temporal lobe epilepsy. This neurotropic DNA virus is ubiquitous and primary infection occurs in up to 80% of children by age two years. While two viral variants have been identified, HHV-6B is the one that has been primarily linked to disease in humans, including epilepsy. After initial viremia, the virus can establish chronic latency in brain tissue, peripherally in tonsils and salivary glands and infect several different cell lines by binding to the complement regulator CD-46. In this review we will focus on discussing the evidence linking HHV-6 infection to different epilepsy syndromes and analyzing proposed pathogenic mechanisms.

Extracellular vesicles (EVs) of various types are released or shed from all cells. EVs carry proteins and contain additional protein and nucleic acid cargo that relates to their biogenesis and cell of origin. EV cargo in liquid biopsies of widespread interest due to its ability to provide a retrospective snapshot of cell state at the time of EV release. For the purposes of EV cargo analysis and repertoire profiling, multiplex assays are an essential tool in multiparametric analyte studies but are still being developed for high-parameter EV protein detection. Although bead-based EV multiplex analyses offer EV profiling capabilities with conventional flow cytometers, the utilization of EV multiplex assays has been limited by the lack of software analysis tools for such assays. Therefore, to facilitate robust EV repertoire studies, we have developed a free, open-source software (MPAPASS) for stitched multiplex analysis, EV database-compatible reporting, and visualization of EV repertoires.

The region known as pX in the 3' end of the human T-cell lymphotropic virus type 1 (HTLV-1) genome contains four overlapping open reading frames (ORF) that encode regulatory proteins. HTLV-1 ORF-I produces the protein p12 and its cleavage product p8. The functions of these proteins have been linked to immune evasion and viral infectivity and persistence. It is known that the HTLV-1 infection does not necessarily imply the development of pathological processes and here we evaluated whether natural mutations in HTLV-1 ORF-I can influence the proviral load and clinical manifestation of HTLV-I-associated myelopathy/tropical spastic paraparesis (HAM/TSP). For that, we performed molecular characterization, datamining and phylogenetic analysis with HTLV-1 ORF-I sequences from 156 patients with negative or positive diagnosis for HAM/TSP. Our analyses demonstrated that some mutations may be associated with the outcome of HAM/TSP (C39R, L40F, P45L, S69G and R88K) or with proviral load (P34L and F61L). We further examined the presence of mutations in motifs of HBZ and observed that P45L mutation is located within the HBZ nuclear localization signal and was found more frequently between patients with HAM/TSP and high proviral load. These results indicate that some natural mutations are located in functional domains of ORF-I and suggests a potential association between these mutations and the proviral loads and development of HAM/TSP. Therefore it is necessary to conduct functional studies aimed at evaluating the impact of these mutations on the virus persistence and immune evasion. ispartof: Infection, Genetics and Evolution vol:45 pages:420-425 ispartof: location:Netherlands status: published

The interplay between viral infection and Alzheimer’s disease (AD) has long been an area of interest but proving causality has been elusive. Several recent studies have renewed the debate concerning the role of herpesviruses, and human herpesvirus-6 (HHV-6) in particular, in AD. We screened for HHV-6 detection across three independent AD brain repositories, using (1) RNAseq datasets and (2) DNA samples extracted from AD and non-AD control brains. The RNAseq data were screened for pathogens against taxon references from over 25,000 microbes, including 118 human viruses, while DNA samples were probed for PCR reactivity to HHV-6A and HHV-6B. HHV-6 demonstrated little specificity to AD brains over controls by either method, while other viruses such as Epstein-Barr virus (EBV) and cytomegalovirus (CMV) were detected at comparable levels. These direct methods of viral detection do not suggest a strong association between HHV-6 and AD.

Following reports of elevated antiviral antibodies in MS patient sera and viral DNA detection in MS plaques nearly two decades ago, the neurovirology community has actively explored how herpesviruses such as HHV-6 might be involved in MS disease pathogenesis. Though findings across the field are non-uniform, an emerging consensus of viral correlates with disease course and evidence of HHV-6-specific immune responses in the CNS provide compelling evidence for a role, direct or indirect, of this virus in MS. Ultimately, the only way to demonstrate the involvement, or lack thereof, of HHV-6 or other herpesviruses in this disease is through a controlled clinical trial of an efficacious antiviral drug.

Background Brain- and lesion-volumes derived from magnetic resonance images (MRI) serve as important imaging markers of disease progression in neurodegenerative diseases and aging. While manual segmentation of these volumes is both tedious and impractical in large cohorts of subjects, automated segmentation methods often fail in accurate segmentation of brains with severe atrophy or high lesion loads. The purpose of this study was to develop an atlas-free brain Classification using DErivative-based Features (C-DEF), which utilizes all scans that may be acquired during the course of a routine MRI study at any center. Methods Proton-density, T2-weighted, T1-weighted, brain-free water, 3D FLAIR, 3D T2-weighted, and 3D T2*-weighted images, collected routinely on patients with neuroinflammatory diseases at the NIH, were used to optimize the C-DEF algorithm on healthy volunteers and HIV + subjects (cohort 1). First, manually marked lesions and eroded FreeSurfer brain segmentation masks (compiled into gray and white matter, globus pallidus, CSF labels) were used in training. Next, the optimized C-DEF was applied on a separate cohort of HIV + subjects (cohort two), and the results were compared with that of FreeSurfer and Lesion-TOADS. Finally, C-DEF segmentation was evaluated on subjects clinically diagnosed with various other neurological diseases (cohort three). Results C-DEF algorithm was optimized using leave-one-out cross validation on five healthy subjects (age 36 ± 11 years), and five subjects infected with HIV (age 57 ± 2.6 years) in cohort one. The optimized C-DEF algorithm outperformed FreeSurfer and Lesion-TOADS segmentation in 49 other subjects infected with HIV (cohort two, age 54 ± 6 years) in qualitative and quantitative comparisons. Although trained only on HIV brains, sensitivity to detect lesions using C-DEF increased by 45% in HTLV-I-associated myelopathy/tropical spastic paraparesis (n = 5; age 58 ± 7 years), 33% in multiple sclerosis (n = 5; 42 ± 9 years old), and 4% in subjects with polymorphism of the cytotoxic T-lymphocyte-associated protein 4 gene (n = 5; age 24 ± 12 years) compared to Lesion-TOADS. Conclusion C-DEF outperformed other segmentation algorithms in the various neurological diseases explored herein, especially in lesion segmentation. While the results reported are from routine images acquired at the NIH, the algorithm can be easily trained and optimized for any set of contrasts and protocols for wider application. We are currently exploring various technical aspects of optimal implementation of CDEF in a clinical setting and evaluating a larger cohort of patients with other neurological diseases. Improving the accuracy of brain segmentation methodology will help better understand the relationship of imaging abnormalities to clinical and neuropsychological markers in disease.

T2⁎-weighted MRI at high field is a promising approach for studying noninvasively the tissue structure and composition of the brain. However, the biophysical origin of T2⁎ contrast, especially in white matter, remains poorly understood. Recent work has shown that R2⁎ (= 1/T2⁎) may depend on the tissue's orientation relative to the static magnetic field (B0) and suggested that this dependence could be attributed to local anisotropy in the magnetic properties of brain tissue. In the present work, we analyzed high-resolution, multi-gradient-echo images of in vivo marmoset brains at 7 T, and compared them with ex vivo diffusion tensor images, to show that R2⁎ relaxation in white matter is highly sensitive to the fiber orientation relative to the main field. We directly demonstrate this orientation dependence by performing in vivo multi-gradient-echo experiments in two orthogonal brain positions, uncovering a nearly 50% change in the R2⁎ relaxation rate constant of the optic radiations. We attribute this substantial R2⁎ anisotropy to local subvoxel susceptibility effects arising from the highly ordered and anisotropic structure of the myelin sheath.

Multiple sclerosis (MS) is a central nervous system inflammatory disorder with evidence of peripheral immune dysregulation. Abnormalities of the immune suppressive cytokine TGF-β have been reported, but not fully defined, in MS. Through a pathway-focused expression profiling of the peripheral blood, we found abnormalities of TGF-βRII, SMAD4 and SMAD7 expression in subjects with MS, and reduction in the levels of TGF-β regulated genes, indicating an overall reduction in TGF-β signaling in MS. The response to exogenous TGF-β was intact, however, indicating an extrinsic defect of TGF-β signaling in MS. These results indicate that TGF-β control is diminished in MS.

The geographic distribution of Human T-cell Lymphotropic Virus Type 1 (HTLV-1) infection makes one thing clear: except Japan, most of the estimated 20 million infected individuals are clustered within communities with limited health care access [1]. Given that the majority of infected persons remain disease-free, one of the challenges of the clinical management of HTLV-1-infected patients with myelopathic symptoms is to establish the definite diagnosis of HTLV-Associated Myelopathy/Tropical Spastic Paraparesis (HAM/TSP). Asymptomatic carriers may complain of a range of symptoms that cannot be excluded from an association with HTLV-1, such as dry eyes, urinary incontinence and constipation. Current HAM/TSP diagnostic procedures are based on criteria established by the World Health Organization (WHO), which consists of a list of neurological signs and symptoms in HTLV-1 seropositive subjects. In addition, imaging of the central nervous system is essential to exclude other neurological diseases with similar clinical features, whilst isolation of HTLV-1 proviral in the cerebrospinal fluid (CSF) [2] is a positive finding, especially when the viral load in CSF lymphocytes is greater than in PBMCs [3]. However, these complementary tests are not readily available in many communities. In our experience, patients rarely present with all the essential features of HAM/TSP to meet the diagnostic requirements of the complete syndrome. To complement WHO criteria, a new classification strategy, the Belem Criteria, based on three diagnostic ascertainment levels was proposed [4]. HTLV-1-infected patients with neurological defects are categorized as: (i) Definite HAM/TSP: patients who meet the established WHO criteria with a complete clinical presentation; (ii) Probable HAM/TSP: patients with a myelopathic mono-symptomatic presentation, in which other diseases resembling HAM/TSP have been excluded; (iii) Possible HAM/TSP: patients who present with a complete or incomplete clinical picture; however, other disorders resembling HAM/TSP cannot be excluded. In recent years, several studies have demonstrated a clear association between HAM/TSP and HTLV-1 proviral load [5-11]. Moreover, compelling evidence indicates that patients with other HTLV-1-associated inflammatory conditions, such as infective dermatitis [12] or keratoconjunctivitis sicca [13], display significantly higher levels of proviral load compared to asymptomatic carriers. In a published study conducted in Bahia, Brazil, we found that a proviral load cut-off value of 50,000 copies/106 PBMCs (5%), differentiated asymptomatic carriers from HAM/TSP patients with 87% sensitivity and 81% specificity [14]. Using the Belem criteria, only 22% of probable and 17% of definite HAM/TSP patients’ HTLV-1 proviral loads fell below this cut-off value. If this threshold had been included as an additional criterion to diagnose HAM/TSP, 73% of patients from the probable group would be reclassified as definite. Furtado et al. [15] also attempted to establish a proviral load cut-off value to distinguish asymptomatic carriers from HAM/TSP patients in Minas Gerais (Brazil). Using whole blood, a cut-off of 114 HTLV-1 copies/104 white blood cells (1.14%), offered 78.2% sensitivity and 28% specificity in patients with HAM/TSP. This value is considerably lower than what was observed in Bahia. As members of the HAM/TSP Clinical Trial Study Group (HAM/TSP-CTSG) we performed a literature review of proviral loads reported in asymptomatic carriers and HAM/TSP patients (Table 1). The percentage of infected cells was approximately 6× higher in HAM/TSP patients (median 6.8%, 5.4–18%) than in asymptomatic carriers (median 1.1%, 0.3–5.6%). Despite overlapping ranges, the trends are consistent across studies. However, study groups used diverse methods to measure proviral load, including different regions of the targeted HTLV-1 genome, the DNA sample source, e.g. whole blood cells or isolated PBMCs and cells quantified from patient samples. In personal consultation with HAM/TSP CTSG members we established that 7.04% and 10% of patients with definite HAM/TSP, living in Bahia, Brazil and Japan respectively, have a proviral load of 1% [3]. Based on the reviewed data and our own observations across four centres (Bahia/Japan/UK/USA) a single cut-off for asymptomatic versus HAM/TSP or for definite versus probable HAM/TSP cannot be recommended. Table 1 Methodological characteristics of HTLV-1 proviral load measurements using PCR method from asymptomatic carriers and HAM/TSP patients in endemic countries for HTLV-1-infection. We therefore propose an international pilot study in an attempt to achieve consistent results in order to evaluate HTLV-1 proviral load in PBMCs of asymptomatic carriers as well as patients with probable, possible and definite HAM/TSP living in HTLV-1 endemic and non-endemic areas. By testing these patients at several chosen established laboratories blinded to samples’ origins, we hope to take initial steps towards the standardization of proviral load quantification technique, with the ultimate goal of determining a relevant proviral load cutoff value to distinguish asymptomatic carriers from HAM/TSP patients. At the same time, we recognize that, due to variation from assay to assay, there are limitations with respect to viral load quantification [16,17]. In the future, the HTLV research community might propose the incorporation of a WHO international standard to aid in clinical applications by soliciting assistance from such groups as Standardization of Genome Amplification Techniques or National Institute for Biological Standards and Control.

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.

The treatment of HAM/TSP is a challenge. No agent has shown to significantly modify the long-term disability associated with HAM/TSP. Advances in our understanding of the pathogenesis of HAM/TSP have led to the identification of several biomarkers and therapeutic targets. Clinical trials in HAM/TSP continue to be opportunities for further qualification and refinement of biomarkers and therapeutic targets. The validation of HAM/TSP relevant biomarkers and the identification of new targets remain key challenges in the development of effective targeted therapy in HAM/TSP.

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.

The human T lymphotropic virus type 1 (HTLV-I) is associated with a chronic, progressive demyelinating disease of the central nervous system (CNS) termed HAM/TSP. This virus is endemic throughout the world and the vast majority of individuals infected with this agent are asymptomatic carriers. A differential host cellular immune response to HTLV-I in an asymptomatic carrier and a disease affected individual may explain the different outcomes of an HTLV-I infection. This report reviews the evidence that supports the involvement of HTLV-I specific cytotoxic T cells in the neuropathology of HTLV-I associated neurological disease. The use of immunotherapeutic strategies to modify disease is discussed based on the observation of high virus-specific cytotoxic T cell responses from lymphocytes obtained from both the peripheral blood and the CNS of HAM/TSP patients.

To investigate the cellular immune effects of the interferon inducer, Poly ICLC, in humans, peripheral blood mononuclear cells from patients with multiple sclerosis receiving Poly ICLC as part of a preliminary clinical trial were studied. Peripheral blood mononuclear cell phenotype analysis using fluoresceinated monoclonal antibodies and flow microfluorometry showed decreases in the percentages and absolute numbers of all lymphocyte subsets 24 h after infusion. These changes returned toward baseline at 48 h except the percentage of CD-4 positive cell which increased above baseline levels. The percentage of HLA-DR antigen positive cells and CD-16 (Leu 11a) positive cells were increased 24 h after infusion but returned to baseline at 48 h. NK activity as determined by chromium release from K562 target cells was decreased at 24 h but increased 48 h after drug infusion. The increases in percentages of HLA-DR antigen and CD-16 positive cells at 24 h and NK activity at 48 h are consistent with the in vitro effects of IFN while the decreases in peripheral blood mononuclear cells are suggestive of changes in cell recirculation.

were interested to analyze the phenotype, function and dynamics of myeloid cell-subsets. Here we show, that depletion of CCR2 Ly6C inflammatory monocytes, a subset of recruited myeloid cells, results in decreased survival, suggesting their critical importance in host defense against T. gondii infection. Moreover, CCR2 Ly6C monocytes produce pro-inflammatory mediators, such as IL-1a, IL-1b, iNOS, TNF and ROS, confirming their anti-parasitic role. Furthermore, we demonstrate by adoptive transfer that inflammatory monocytes develop into two distinct subpopulations: CCR2 Ly6C F4/80 and CCR2 Ly6C F4/80. The CCR2 Ly6C F4/80 cells perform dendritic cell like functions such as interacting with T cells via MHC I and MHC II molecules. The CCR2 Ly6C F4/80 cell subset displays elevated phagocytic capacity and upregulates TREM2. Finally, we show that recruitment of Ly6C monocytes to the CNS is mediated by selectins. These results indicate the crucial role of recruited Ly6C monocytes upon cerebral toxoplasmosis, unraveling the dynamics and function of further differentiated mononuclear cell subsets in parasite control and immune regulation in the CNS.

s, 5th Int. Conf. on HHV-6&7, 1–3 May 2006, Barcelona, Spain / Journal of Clinical Virology 37 Suppl. 1 (2006) S97–118 S113 58 Efficacy of anti-viral compounds in HHV-6 infected glial cells J. Fotheringham*, N. Akhyani, F. Rashti, K. Yao, E. Williams, S. Jacobson. Viral Immunology Section, National Institute of Neurological Disorders and Stroke, National Institutes of Health, 10 Center Drive, Bethesda, MD, 20892, USA E-mail address: fotherij@ninds.nih.gov Background: Human herpesvirus 6 (HHV-6) infects the central nervous system and is associated with neurological diseases including encephalitis, epilepsy and multiple sclerosis. Reactivation of latent HHV-6 occurs in the CNS, particularly in immunocompromised patients, and contributes to post-bone marrow transplant (BMT) complications. HHV-6 DNA was detected in cerebrospinal fluid (CSF) from 5 patients who presented with mental status changes post-BMT. In autopsy material from 3 patients, active HHV-6 infection was determined by detection of viral DNA, RNA and protein. HHV-6 viral protein was found predominantely in reactive astrocytes, suggesting an in vivo glial tropism of HHV-6. Although HHV-6 is becoming increasingly recognized as an important pathogen in the CNS, there are currently no anti-viral drugs approved for HHV-6. Currently used anti-virals are approved for the herpesvirus cytomegalovirus (CMV) and have only been studied for anti-HHV-6 activity in T cells and have demonstrated limited success in treating HHV-6 associated CNS complications post-BMT. Objectives: To study the anti-HHV-6 activity of anti-viral drugs in astrocytes and T cells. Study Design: The astrocytic cell line U251 and the T cell line SupT1 were infected with both variants of HHV-6, A and B. Infections were monitored by quantitative TaqMan PCR for viral load, by RT-PCR for viral RNA expression, and by IFA for viral protein expression. Anti-viral activity of ganciclovir, acyclovir, foscarnet and cidofovir was determined by changes in cellular viral load in drug-treated compared to non-drug treated HHV-6 infected cell cultures. Results: All drugs demonstrated anti-viral activity against HHV-6A and HHV-6B in infected T cells consistent with other published studies. wever, only cidofovir and foscarnet demonstrated activity in HHV-6A infected astrocytes. Conclusions: These results suggest that HHV-6 reactivation is associated with CNS complications post-BMT and that HHV-6 exhibits tropism for astrocytes in vivo, however currently used anti-viral drugs demonstrate limited efficacy in HHV-6 infected astrocytes in vitro. 59 Experimental/alternative therapeutic approaches for HHV-6 infection J.H. Brewer*. Plaza Infectious Disease and St. Luke’s Hospital, Kansas City, MO, USA E-mail address: jbrewer@plazamedicine.com Background: Experimental (alternative) treatment approaches may be useful for disease states that have been associated with HHV-6 infection. Such therapy alternatives may have immune modulating properties, antiviral activity or both. Objectives: A literature review was conducted for various experimental therapies in HHV-6 infection and associated disease states. Study Design: Literature review. Results: The following therapies were reviewed with emphasis on microbiologic and clinical data from published studies. 1. Immune globulin (clinical studies of CFS and MS patients treated with IVIG) 2. Interferon (results of beta interferon in microbiologic studies with HHV-6 and clinical studies with MS patients) 3. Ampligen (microbiologic studies and clinical data with CFS) 4. Transfer Factor (clinical data for herpesviruses and specifically for HHV-6/CFS patients) 5. Isoprinosine (clinical data with CFS) 6. Kutapressin (preliminary microbiologic data) Conclusions: Several experimental therapies have been studied in patients with HHV-6 infection and associated disease states. Such therapies may have future potential as treatment options. 60 Review of Ampligen clinical trials in chronic fatigue syndrome W. Mitchell1 *, Chronic Fatigue Syndrome Clinical Consortium2. 1Department of Pathology, Vanderbilt University School of Medicine, Nashville, TN, USA, 2Hemispherx Biopharma, Philadelphia, PA

The ultrastructural replication cycle of human herpesvirus 6A and 6B, both T-lymphotropic viruses, with tropism for the central nervous system,wascomparedbyelectronmicroscopyin the same cells, that is, in the T-lymphoblastoid cell line SupT-1 and in human astrocytes. Both HHV-6A and HHV-6B replicated efficiently in SupT-1 and formed viral particles. The tegument is the least characterized structure of the herpesviral particle and both variants were able to form intranuclear membrane compartments called tegusomes in SupT-1 where tegumentation occurred. Also, tegumentation occurred in HHV6A infected cells in the nucleoplasm without the presence of a tegusome. This suggests that there is more than one possible route of tegumentation.Differencesinthereplicationcyclesbetween

We measured lymphocyte proliferation in the absence of antigenic stimulation in 45 HTLV-II infected, 9 HTLV-I infected, and 19 HTLV-I seronegative intravenous drug users (IVDU). Lymphocyte proliferation was higher in IVDUs infected with HTLV-II than in seronegative IVDUs but lower than among those infected with HTLV-I. Higher rates of proliferation were also associated with needle sharing, CD4+ and IL2R+ lymphocyte counts, and HTLV-I antibody titres.

An impairment of the measles virus-specific cytotoxic T lymphocyte response in multiple sclerosis was previously reported. This response is predominantly mediated by HLA class II-restricted CD4 + cells. In the present report, virus-specific cytotoxic T lymphocyte responses in multiple sclerosis were further studied by examining the response to mump virus. No significant difference was detected in the generation of mumps virus-specific cytotoxic T lymphocyte responses between normal individuals and multiple sclerosis patients with impaired measles virus-specific cytotoxicity. A portion of the mumps virus-specific cytotoxic T lymphocyte response could be mediated by HLA class II-restricted CD4 + cells generated from both normal controls and MS patients. This CD4 + cell-mediated portion of the response was similar in both groups. These findings support the view that there is a distinct measles virus-specific impairment in cell-mediated cytotoxicity in multiple sclerosis.

HLA-DR2 can be divided into at least 3 distinct HLA-D clusters which correlate with structural differences within the HLA-D region. Further, a functional counterpart of this subdivision has been previously identified. The presence of a particular DR beta 2 polypeptide chain correlated precisely with the susceptibility of measles virus-infected HLA-DR2 homozygous typing cell lines to lysis by measles virus-specific, HLA class II-restricted CTL clones. To determine if a genetic basis for these functional differences could be detected, the degree of polymorphism at the DNA level within the serologically defined HLA-DR2 haplotype has been examined. By using DNA probes for DR beta and DQ beta 4 of the 5 HLA-D clusters of HLA-DR2 could be distinguished and a RFLP pattern was identified which correlates with known immunological functions associated with these various D types. In addition, this technique of 'molecular genotyping' was used to investigate a limited panel of patients with multiple sclerosis (MS) who were HLA typed as either HLA-DR2,2 or HLA-DR2,blank. The RFLP profile of the HLA-DR2 Dw2 D type was found in all of these MS patients.

Spontaneous lymphocyte proliferation was studied in HTLV-1-infected but symptom-free individuals to see if factors such as demographics or socioeconomics influence spontaneous proliferation in Jamaicans. Among the 30 healthy Jamaicans the only demographic feature (age sex socioeconomic status) associated with high lymphoproliferation was low income. However logistic regression analysis revealed that HTLV-1 seropositivity was a stronger risk factor for high lymphoproliferation (odds ratios (OR) = 17.2 95% confidence intervals (CI) 1.8-164.7) than was low income (OR = 8.5 95% CI 0.9-81.6). Besides adult T-cell leukemia/lymphoma (ATL) and HTLV-1-associated myelopathy/tropical spastic paraparesis (HAM/TSP) HTLV-1 infection has been associated with immunodeficiency and in-vitro immunological effects including perturbations in T-cell subsets. The data suggest that increased spontaneous lymphoproliferation is associated with HTLV-1 exposure per se. HTLV-1-negative black Jamaicans had significantly higher lymphoproliferation than US white controls. The reason for this finding is unclear. Genetic factors may account for the difference. However it is also possible that spontaneous proliferation is influenced by exposure to antigens and pathogens; and multiple infections are more common in Jamaica than in the US.