Simian immunodeficiency (SIV) multiple antigenic peptide–enzyme immunoassay (SMAP-EIA) seroreactivity trends to SIV immunodominant region (IDR) peptides in HIV-seronegative Cameroonian population groups with different levels of exposure (high exposure [HE], low exposure [LE], or general [G]) to nonhuman primates. OD, optical density. χ2 linear trend 48.166, p<0.001.

Interferon-γ enzyme-linked immunospot reactivity stimulated with SIVcol peptides from the env and gag regions in peripheral blood lymphocytes (PBLs) from a person seropositive for both the SIVcol V3 and immunodominant region (IDR) peptides and a seronegative person from Africa (both men). To include both assays in a single graph, the number of spots per 106 PBLs for each pool of gag peptides was divided by the number of spots per 106 PBLs in the medium control. This value was expressed as the level of reactivity above background; i.e., the value 2 on the y-axis stands for 2× the number of spots in the negative (medium) control.