1. HLA-associated polymorphisms in the HIV-2 capsid highlight key differences between HIV-1 and HIV-2 immune adaptation.
- Author
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de Silva TI, Leligdowicz A, Carlson J, Garcia-Knight M, Onyango C, Miller N, Yindom LM, Hué S, Jaye A, Dong T, Cotten M, and Rowland-Jones SL
- Subjects
- Case-Control Studies, Evolution, Molecular, Guinea-Bissau, HIV Infections immunology, HIV-1 genetics, HIV-2 genetics, Humans, Immune Evasion, Models, Statistical, Selection, Genetic, T-Lymphocytes, Cytotoxic immunology, Adaptation, Biological, Capsid Proteins genetics, HIV Infections virology, HIV-1 immunology, HIV-2 immunology, Phosphoproteins metabolism, Polymorphism, Genetic
- Abstract
Objective: HIV-1 frequently adapts in response to immune pressure from cytotoxic T-lymphocytes (CTL). Many HIV-2 infected individuals have robust capsid-specific CTL responses associated with viral control. Despite this CTL pressure, adaptive changes in this key immunogenic HIV-2 protein have not previously been described. We sought to compare selective pressure on HIV-1 and HIV-2 capsids and identify HLA-associated viral polymorphisms in HIV-2., Design and Methods: Bioinformatic algorithms to identify sites under positive and negative selective pressure and a statistical model of evolution to identify HLA-associated polymorphisms in HIV-2 was applied to sequences from a community cohort in Guinea-Bissau. IFN-γ ELISpots were used to compare T-cell responses to wild-type and variant epitopes., Results: We identified greater purifying selection and less sites under positive selective pressure in HIV-2 compared with HIV-1. Five HIV-2 codons with HLA-associated polymorphisms were detected all within or around known or predicted CTL epitopes. One site was within the HLA-B58 SuperType (ST)-restricted epitope (TSTVEEQIQW), the HIV-2 equivalent of the HIV-1 TW10 epitope. In contrast to HIV-1, where a T→N mutation at position 3 is associated with resulting loss of CTL control, an E→D mutation at position 5 was observed in HIV-2. Robust CTL responses to the variant HIV-2 epitope were seen, suggesting that HIV-2 adaptation may be at the level of T-cell receptor recognition., Conclusion: Greater constraints on evolution may exist in HIV-2, resulting in more purifying selection and different immune adaptation pathways in HIV-1 and HIV-2 capsids. This may allow CTL responses to persist in HIV-2.
- Published
- 2018
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