(A,B) Assessment of the outcome of effective challenge by
longitudinal analysis of plasma viral load (A) and de
novo development of SIV Vif-specific CD4+
(B, top panel) and CD8+ (B, bottom
panel) T cell responses. RM were challenged until the onset of any
above-threshold SIV Vif-specific T cell response, with the SIV dose administered
2 or 3 weeks prior to this response detection considered the infecting challenge
(week 0). RM with sustained viremia were considered not protected (black); RM
with no or transient viremia were considered protected (red) (8). The fraction of protected RM in the vaccinated
groups (Groups 1 and 2, n = 13 and 14, respectively) were compared to that of
the unvaccinated group (Group 3, n = 17) by Barnard’s exact test of
binomial proportions, with the P-values shown in (A). (C) BM cells
and PBMC were collected and cryopreserved from
ΔRh110/SIVmac239/smE660 vaccine-protected RM without any
detectable viremia (RM #1, RM #2, RM #3 from Group 1; RM #4, RM #5, RM #6 from
Group 2) at the indicated time points post-effective challenge (left panel; PID
– post-infection day). Cells were thawed and administered intravenously
(left panel) to 6 SIV-naïve RM to assess the presence of
replication-competent SIV with the plasma viral dynamics in recipient RM shown
(right panel).