Prevention of SIVmac251 reservoir seeding in rhesus monkeys by early antiretroviral therapy

Abstract

The precise time when the viral reservoir is seeded during acute HIV-1 infection remains unclear. We previously demonstrated that the viral reservoir was seeded by day 3 following SIVmac251 infection in rhesus monkeys. Here we report the impact of initiating ART on day 0 (6 h), 1, 2, or 3 following intrarectal SIVmac251 infection in 20 rhesus monkeys (N = 5/group). After 6 months of daily suppressive ART, antiretroviral drugs were discontinued, and viral rebound was monitored. 0% (0 of 5), 20% (1 of 5), 60% (3 of 5), and 100% (5 of 5) of animals that initiated ART on days 0 (6 h), 1, 2, or 3, respectively, showed viral rebound following ART discontinuation and correlated with integrated viral DNA in lymph node CD4+ T cells. These data demonstrate that the viral reservoir is seeded within the first few days of infection and that early ART initiation limits the viral reservoir.

Fig. 1

Plasma viral kinetics in SIV-infected rhesus monkeys following initiation of ART on days 0, 1, 2 and 3 post infection. Log plasma SIV RNA was monitored in rhesus monkeys following initiation of ART (N = 5/group) on day 0 (6 h), day 1, day 2, and day 3 following intrarectal SIVmac251 infection. Assay limit of detection (<50 RNA copies/ml) and day of ART initiation are indicated with hatched lines

Fig. 2

SIV DNA in blood and tissues pre-ART and at ART discontinuation. Cell-associated SIV DNA in a peripheral blood mononuclear cells (PBMC), b lymph node mononuclear cells (LNMC), and c gastrointestinal mucosa mononuclear cells (GMMC) in animals that initiated ART on days 0, 1, 2, and 3 following infection. Log SIV DNA copies/10⁶ total CD4+ T cells is shown. Changes in levels of viral DNA prior to ART and at the time of ART discontinuation were compared using a Wilcoxon rank sum test. p values are not significant unless they are indicated. Assay sensitivity, as indicated by the hatched line, is <3 copies/10⁶ cells

Fig. 3

Comparison of SIV DNA in CD4+ memory T cell subsets. Mononuclear cells were isolated from tissues of animals that initiated ART on days 0, 1, 2 and 3 following infection and sorted into populations of CD4+ T cells: a lymph node naïve, central memory (T_CM), follicular helper T cells (T_FH) and effector memory (T_EM); b colon naive and memory. SIV DNA is expressed as log copies/10⁶ CD4+ T cells at the time of ART initiation and stopping ART. All data points are shown with the median expressed as bars. p values reflect t-tests that were used to compare means of proviral DNA in each subset between each group

Fig. 4

Comparison of integrated SIV DNA in CD4+ T cell subsets following ART discontinuation. a Total and integrated levels of SIV DNA in sorted naive and memory CD4+ T cells in GMMC and b naive, central memory (T_CM), follicular helper (T_FH) and effector and effector memory (T_EM) CD4+ T cells in LNMC are shown. Ten animals that initiated ART on day 1 (n = 5) or 2 (n = 5) were divided into two groups: animals that did not rebound (n = 6) and animals that did rebound (n = 4) following ART withdrawal. All data points are shown. Bars indicate the median of values. p values reflect Fisher’s exact test to compare the frequency of the SIV DNA positive sample distribution between each group

Fig. 5

Viral rebound kinetics following ART discontinuation. a ART was discontinued after 24 weeks, and plasma SIV RNA was assessed on days 0, 3, 7, 10, 14, and then weekly. b Kaplan–Meier curve showing the time to viral rebound for each group of animals. The differences between groups were analyzed by the log-rank test and p value is indicated