Antigen-specific cytokine responses in vaccinated Macaca nemestrina

: We describe a new surrogate assay for CD8 + T lymphocyte activity that has the capability of discriminating between cytotoxic T lymphocyte (CTL) activity and cytokine‐mediated suppressive activity. We applied this approach to two groups of Macaca nemestrina vaccinated with a minimally pathogenic strain of human immunodeficiency virus type 2 [HIV‐2 (HIV‐2KR)] as a model of an attenuated virus vaccine. Group 1 was then inoculated with a non‐infectious stock of a pathogenic strain, HIV‐2287. Both groups 1 and 2 were subsequently challenged with an infectious stock of HIV‐2287. Five out of six group 1 animals were protected against CD4 decline, whereas three out of six animals in group 2 were protected. Analysis of CTL responses demonstrated strong activity against HIV‐2KR‐Gag in group 1. It was determined that strong CTL responses correlate with antigen‐specific T‐helper (Th) type 1 responses. This antigen‐specific cytokine assay has the potential to better elucidate the functional mechanisms of CD8 + T‐cell‐mediated protection than traditional methods to date.