De Novo Generation of Escape Variant-Specific CD8 + T-Cell Responses following Cytotoxic T-Lymphocyte Escape in Chronic Human Immunodeficiency Virus Type 1 Infection

Abstract

ABSTRACT Human immunodeficiency virus type 1 (HIV-1) evades CD8 + T-cell responses through mutations within targeted epitopes, but little is known regarding its ability to generate de novo CD8 + T-cell responses to such mutants. Here we examined gamma interferon-positive, HIV-1-specific CD8 + T-cell responses and autologous viral sequences in an HIV-1-infected individual for more than 6 years following acute infection. Fourteen optimal HIV-1 T-cell epitopes were targeted by CD8 + T cells, four of which underwent mutation associated with dramatic loss of the original CD8 + response. However, following the G 357 S escape in the HLA-A11-restricted Gag 349-359 epitope and the decline of wild-type-specific CD8 + T-cell responses, a novel CD8 + T-cell response equal in magnitude to the original response was generated against the variant epitope. CD8 + T cells targeting the variant epitope did not exhibit cross-reactivity against the wild-type epitope but rather utilized a distinct T-cell receptor Vβ repertoire. Additional studies of chronically HIV-1-infected individuals expressing HLA-A11 demonstrated that the majority of the subjects targeted the G 357 S escape variant of the Gag 349-359 epitope, while the wild-type consensus sequence was significantly less frequently recognized. These data demonstrate that de novo responses against escape variants of CD8 + T-cell epitopes can be generated in chronic HIV-1 infection and provide the rationale for developing vaccines to induce CD8 + T-cell responses directed against both the wild-type and variant forms of CD8 epitopes to prevent the emergence of cytotoxic T-lymphocyte escape variants.