Immunotherapy during the acute SHIV infection of macaques confers long-term suppression of viremia

We report that combination bNAb immunotherapy initiated on day 3 post-infection (PI) maintained durable CD8(+) T cell–mediated suppression of SHIV(AD8) viremia and preinoculation levels of CD4(+) T cells in 9 of 13 treated monkeys during nearly 6 yr of observation, as assessed by successive CD8(+) T cell–depletion experiments. In an extension of that study, two treatment interventions (bNAbs alone or cART plus bNAbs) beginning on week 2 PI were conducted and conferred controller status to 7 of 12 monkeys that was also dependent on control mediated by CD8(+) cells. However, the median time to suppression of plasma viremia following intervention on week 2 was markedly delayed (85 wk) compared with combination bNAb immunotherapy initiated on day 3 (39 wk). In both cases, the principal correlate of virus control was the induction of CD8(+) T cellular immunity.