HLA and AIDS: a cautionary tale

ArticleinTrends in Molecular Medicine 7(9):379-381 · October 2001with8 Reads
DOI: 10.1016/S1471-4914(01)02131-1 · Source: PubMed
Abstract
The human major histocompatibility complex HLA has been implicated repeatedly as a regulator of the outcome of HIV exposure and infection. A new study of long-term survivors who naturally depress HIV-1 replication and avoid the signs of AIDS for years after infection suggests that homozygosity for a group of HLA-B locus alleles termed Bw4 confers resistance, ostensibly by regulating natural killer cell–ligand interactions. However, close inspection of the accumulated evidence raises some questions and urges validation of the potential Bw4 effects in additional studies.
    • "The highly polymorphic human leukocyte antigen class I (HLA-I) molecules present HIV- 1-derived peptide epitopes on the surface of infected cells, targeting these for elimination by cytotoxic T lymphocytes (CTL). HLA-Is are thus critical to HIV-1 immune control [1, 2]. They also represent strong evolutionary pressures that drive the selection of CTL escape mutations in the HIV-1 genome3456, which act by disrupting intracellular epitope processing [7, 8], abrogating viral peptide-HLA binding [9], or altering interactions between the HLA-bound peptide and the T-cell receptor (TCR)[10] . "
    [Show abstract] [Hide abstract] ABSTRACT: HIV-1 escape from CTL is predictable based on the Human Leukocyte Antigen (HLA) class I alleles expressed by the host. As such, HIV-1 sequences circulating in a population of hosts will harbor escape mutations specific to the HLA alleles of that population. In theory, this should increase the frequency of escape mutation transmission to persons expressing the restricting HLA allele, thereby compromising host immunity to the incoming HIV-1 strain. However, the clinical impact of infection with HIV-1 containing immune escape mutations has not conclusively been demonstrated. Japan’s population features limited HLA diversity which is driving population-level HIV adaptation: for example, >60% of Japanese express HLA-A*24:02 and its associated Nef-Y135F escape mutation represents the population consensus. As such, Japan is an ideal population in which to examine this phenomenon. Here, we combine genetic and immunological analyses to identify A*24:02-positive individuals likely to have been infected with Y135F-containing HIV-1. Over a ~5 year follow-up, these individuals exhibited significantly lower CD4 counts compared to individuals inferred to have been infected with wild-type HIV-1. Our results support a significant negative clinical impact of pathogen adaptation to host pressures at the population level.
    Full-text · Article · Mar 2016
    • "The Mann–Whitney paired test was used to compare the prevalence of HLA-associated polymorphisms in the presence/absence of their restricting HLA, in early versus chronic cohorts, as these data were non-normally distributed. Pearson’s correlation was used to investigate the relationship between early escape prevalence and published first-year rates of escape [13], as well as with published HLA allele-specific Hazard Ratios for progression to AIDS [36], as these data did not significantly violate the assumption that values were drawn from a normal distribution. In single analyses, significance is denoted by p < 0.05. "
    [Show abstract] [Hide abstract] ABSTRACT: Background The reproducible nature of HIV-1 escape from HLA-restricted CD8+ T-cell responses allows the identification of HLA-associated viral polymorphisms ¿at the population level¿ ¿ that is, via analysis of cross-sectional, linked HLA/HIV-1 genotypes by statistical association. However, elucidating their timing of selection traditionally requires detailed longitudinal studies, which are challenging to undertake on a large scale. We investigate whether the extent and relative timecourse of immune-driven HIV adaptation can be inferred via comparative cross-sectional analysis of independent early and chronic infection cohorts.ResultsSimilarly-powered datasets of linked HLA/HIV-1 genotypes from individuals with early (median¿<¿3 months) and chronic untreated HIV-1 subtype B infection, matched for size (N¿>¿200/dataset), HLA class I and HIV-1 Gag/Pol/Nef diversity, were established. These datasets were first used to define a list of 162 known HLA-associated polymorphisms detectable at the population level in cohorts of the present size and host/viral genetic composition. Of these 162 known HLA-associated polymorphisms, 15% (occurring at 14 Gag, Pol and Nef codons) were already detectable via statistical association in the early infection dataset at p¿¿¿0.01 (q¿<¿0.2) ¿ identifying them as the most consistently rapidly escaping sites in HIV-1. Among these were known rapidly-escaping sites (e.g. B*57-Gag-T242N) and others not previously appreciated to be reproducibly rapidly selected (e.g. A*31:01-associated adaptations at Gag codons 397, 401 and 403). Escape prevalence in early infection correlated strongly with first-year escape rates (Pearson¿s R¿=¿0.68, p¿=¿0.0001), supporting cross-sectional parameters as reliable indicators of longitudinally-derived measures. Comparative analysis of early and chronic datasets revealed that, on average, the prevalence of HLA-associated polymorphisms more than doubles between these two infection stages in persons harboring the relevant HLA (p¿<¿0.0001, consistent with frequent and reproducible escape), but remains relatively stable in persons lacking the HLA (p¿=¿0.15, consistent with slow reversion). Published HLA-specific Hazard Ratios for progression to AIDS correlated positively with average escape prevalence in early infection (Pearson¿s R¿=¿0.53, p¿=¿0.028), consistent with high early within-host HIV-1 adaptation (via rapid escape and/or frequent polymorphism transmission) as a correlate of progression.Conclusion Cross-sectional host/viral genotype datasets represent an underutilized resource to identify reproducible early pathways of HIV-1 adaptation and identify correlates of protective immunity.
    Full-text · Article · Aug 2014
    • "The plasticity of the immune system and therefore the ability to adapt to the changing virus seems to be greater in acute than in chronic infection. Interestingly, in our findings the shifting responses towards the mutant antigens where partly restricted by HLA-alleles associated with faster progression to AIDS (HLA-B*35:01, HLA-A*01) [40]. "
    [Show abstract] [Hide abstract] ABSTRACT: HIV evades CD8 T cell mediated pressure by viral escape mutations in targeted CD8 T cell epitopes. A viral escape mutation can lead to a decline of the respective CD8 T cell response. Our question was what happened after the decline of a CD8 T cell response and - in the case of viral escape - if a new CD8 T cell response towards the mutated antigen could be generated in a population not selected for certain HLA alleles. We studied 19 antiretroviral-naïve HIV-1 infected individuals with different disease courses longitudinally. A median number of 12 (range 2-24) CD8 T cell responses towards Gag and Nef were detected per study subject. A total of 30 declining CD8 T cell responses were studied in detail and viral sequence analyses showed amino acid changes in 25 (83%) of these. Peptide titration assays and definition of optimal CD8 T cell epitopes revealed 12 viral escape mutations with one de-novo response (8%). The de-novo response, however, showed less effector functions than the original CD8 T cell response. In addition we identified 4 shifts in immunodominance. For one further shift in immunodominance, the mutations occurred outside the optimal epitope and might represent processing changes. Interestingly, four adaptations to the virus (the de-novo response and 3 shifts in immunodominance) occurred in the group of chronically infected progressors. None of the subjects with adaptation to the changing virus carried the HLA alleles B57, B*58:01 or B27. Our results show that CD8 T cell responses adapt to the mutations of HIV. However it was limited to only 20% (5 out of 25) of the epitopes with viral sequence changes in a cohort not expressing protective HLA alleles.
    Full-text · Article · Dec 2013
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