Fig 1.

Mucosal challenge exposure of macaques to low repeated doses of SIV_mac251 dose. (A) Schematic representation of the study design. Four weeks after last immunization (week 28), macaques were exposed to a total of five repeated doses of SIV_mac251 (120 TCID₅₀ each) given weekly by the intrarectal route. (B) The rate of infection in the three groups is depicted; ALVAC-SIV/gp120, solid black line; gp120, dark dotted line; and control, light dotted line. SIV RNA levels in plasma of control (C), gp120-immunized (D), and ALVAC-SIV/gp120-immunized (E) animals. The animals that remained uninfected in the ALVAC-SIV/gp120 (M624, P250, and P148) group and the one in the gp120 group (M927) are boxed. (F) Geometric mean SIV RNA levels ± standard error in plasma of ALVAC-SIV/gp120 (triangle), gp120 (square), and control (circle) animals. (G) Viral DNA copies in rectal biopsy specimens collected at day 19 after infection or after the fifth exposure to a low dose of SIV_mac251 in the animals that remained uninfected (open symbols). (H) Mean percentage of change in blood CD4⁺ T cell number following SIV_mac251 infection. The uninfected animals are excluded from the analysis. Number of virus variants transmitted in control (I), gp120-immunized (J), and ALVAC-SIV/gp120-immunized (K) macaques.