HLA alleles determine human T-lymphotropic virus-I (HTLV-I) proviral load and the risk of HTLV-I-associated myelopathy.

Department of Immunology, Imperial College School of Medicine, St. Mary's, Norfolk Place, London W2 1PG, United Kingdom.
Proceedings of the National Academy of Sciences (Impact Factor: 9.81). 04/1999; 96(7):3848-53.
Source: PubMed

ABSTRACT The risk of disease associated with persistent virus infections such as HIV-I, hepatitis B and C, and human T-lymphotropic virus-I (HTLV-I) is strongly determined by the virus load. However, it is not known whether a persistent class I HLA-restricted antiviral cytotoxic T lymphocyte (CTL) response reduces viral load and is therefore beneficial or causes tissue damage and contributes to disease pathogenesis. HTLV-I-associated myelopathy (HAM/TSP) patients have a high virus load compared with asymptomatic HTLV-I carriers. We hypothesized that HLA alleles control HTLV-I provirus load and thus influence susceptibility to HAM/TSP. Here we show that, after infection with HTLV-I, the class I allele HLA-A*02 halves the odds of HAM/TSP (P < 0.0001), preventing 28% of potential cases of HAM/TSP. Furthermore, HLA-A*02(+) healthy HTLV-I carriers have a proviral load one-third that (P = 0.014) of HLA-A*02(-) HTLV-I carriers. An association of HLA-DRB1*0101 with disease susceptibility also was identified, which doubled the odds of HAM/TSP in the absence of the protective effect of HLA-A*02. These data have implications for other persistent virus infections in which virus load is associated with prognosis and imply that an efficient antiviral CTL response can reduce virus load and so prevent disease in persistent virus infections.

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    ABSTRACT: Background Immunogenetic evidence indicates that cytotoxic T lymphocytes (CTLs) specific for the weak CTL antigen HBZ limit HTLV-1 proviral load in vivo, whereas there is no clear relationship between the proviral load and the frequency of CTLs specific for the immunodominant antigen Tax. In vivo, circulating HTLV-1-infected cells express HBZ mRNA in contrast, Tax expression is typically low or undetectable. To elucidate the virus-suppressing potential of CTLs targeting HBZ, we compared the ability of HBZ- and Tax-specific CTLs to lyse naturally-infected cells, by co-incubating HBZ- and Tax-specific CTL clones with primary CD4+ T cells from HLA-matched HTLV-1-infected donors. We quantified lysis of infected cells, and tested whether specific virus-induced host cell surface molecules determine the susceptibility of infected cells to CTL-mediated lysis.ResultsPrimary infected cells upregulated HLA-A*02, ICAM-1, Fas and TRAIL-R1/2 in concert with Tax expression, forming efficient targets for both HTLV-1-specific CTLs and CTLs specific for an unrelated virus. We detected expression of HBZ mRNA (spliced isoform) in both Tax-expressing and non-expressing infected cells, and the HBZ26¿34 epitope was processed and presented by cells transfected with an HBZ expression plasmid. However, when coincubated with primary cells, a high-avidity HBZ-specific CTL clone killed significantly fewer infected cells than were killed by a Tax-specific CTL clone. Finally, incubation with Tax- or HBZ-specific CTLs resulted in a significant decrease in the frequency of cells expressing high levels of HLA-A*02.ConclusionsHTLV-1 gene expression in primary CD4+ T cells non-specifically increases susceptibility to CTL lysis. Despite the presence of HBZ spliced-isoform mRNA, HBZ epitope presentation by primary cells is significantly less efficient than that of Tax.
    Retrovirology 12/2014; 11(1):116. DOI:10.1186/PREACCEPT-4681211641356800 · 4.77 Impact Factor
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    ABSTRACT: HTLVI-1 is the first human retrovirus with limited endemic regions in the world. The epidemiological studies have shown that the genetic background and immune response to the virus have a significant role in HTLV-I-associated diseases. Among the genes are involved in HTLV-I infection, the role of human leukocytes antigen (HLA) have been studied in different population. In the present study we examined the association between HLA-DQB1 alleles and HTLV-I infection in HAM/TSP patients, HTLV-I carriers and healthy controls in north east of Iran, Mashhad. The blood samples of 16 patients with HAM/TSP, 20 HTLV-1 carriers, and 30 healthy individuals were taken and DNA was extracted by salting out method. HLA-DQB1 typing was performed using PCR-SSP method and the frequency of HLA-DQB1 alleles were compared by Fischer Exact Test. There was a significant difference between HAM/TSP patients and healthy controls in the frequency of HLA-DQB1*07 (P=0.004, RR=7). Furthermore, we found that possession of HLA- DQB1*02 or HLA-DQB1*05 increased the risk of disease 1.5 times. The data presented here suggest that both HLA-DQB1*07 and HLA-DQB1*06 are associated with disease development.
    Iranian Journal of Basic Medical Sciences 10/2014; 17(10):798-801. · 0.60 Impact Factor

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