Cross-Clade Cytotoxic T Cell Response to Human Immunodeficiency Virus Type 1 Proteins among HLA Disparate North Americans and Thais

A globally effective vaccine will need to elicit cytotoxic T lymphocytes (CTL) capable of recogniz-ing diverse human immunodeficiency virus type 1 (HIV-1) clades. Study of the cellular immune responses of HIV-1–infected persons may allow predictions to be made regarding useful vaccine antigen components. The frequency and magnitude of CTL responses to clade E and B Gag, Pol-RT, Env, and Nef proteins were compared in 12 HLA-characterized, clade E–infected Thais and in 10 clade B–infected North Americans using vaccinia recombinant constructs for protein expres-sion. While responses were detected against all proteins, they were most frequent and cross-reactive to Gag in both groups. Pol-RT was recognized less frequently in Thais than North Americans. Cross-clade protein recognition was common but not uniformly present among these HLA-disparate individuals. Population-specific CTL data are needed to adequately prepare for vaccine trials outside of North America and Europe. A preventative vaccine is the only rational answer for the of target cells expressing divergent HIV-1 clade antigens [11]. However, both homologous (same clade) and heterologousglobal human immunodeficiency virus type 1 (HIV-1) pan-demic that continues to disproportionately affect the developing (cross-clade) target recognition differed among subjects with distinct HLA alleles, indicating the restricted nature of the CTLworld. However, the diversity of the virus with⁄10 geneticall