Although patients with human immunodeficiency virus type 1 infection who are receiving antiretroviral therapy and those with long-term, nonprogressive infection (LTNPs) usually have undetectable viremia, virus persists in tissue reservoirs throughout infection. However, the distribution and magnitude of viral persistence and replication in tissues has not been adequately examined. Here, we used the simian immunodeficiency virus (SIV) macaque model to quantify and compare viral RNA and DNA in the small (jejunum) and large (colon) intestine of LTNPs. In LTNPs with chronic infection, the colon had consistently higher viral levels than did the jejunum. The colon also had higher percentages of viral target cells (memory CD4(+) CCR5(+) T cells) and proliferating memory CD4(+) T cells than did the jejunum, whereas markers of cell activation were comparable in both compartments. These data indicate that the large intestine is a major viral reservoir in LTNPs, which may be the result of persistent, latently infected cells and higher turnover of naive and central memory CD4(+) T cells in this major immunologic compartment.

Understanding HIV latent reservoirs in tissues is essential for the development of new strategies targeting these sites for eradication. Here, we assessed the size of latent reservoirs and the source of residual viruses in multiple lymphoid tissues of SIV-infected and fully suppressed rhesus macaques of Chinese-origin (cRMs). Eight cRMs were infected with SIVmac251 and treated with tenofovir and emtricitabine daily for 24 weeks initiated 4 weeks post-infection. Four of the eight animals reached sustained full viral suppression with undetectable viremia. The levels of cell-associated SIV DNA varied in peripheral blood mononuclear cells (PBMCs) and multiple lymphoid tissues, but with higher levels in the mesenteric lymph nodes (MesLNs). The levels of cell-associated SIV RNA also varied in different tissues. The higher frequency of viral RNA detection in the MesLNs was also observed by in situ hybridization. Consistently, the infection unit per million cells (IUPM) in the MesLNs was higher than in PBMCs and other tested lymphoid tissues by quantitative viral outgrowth assay (QVOA). Furthermore, env gp120 from tissue SIV RNA was amplified by single genome amplification. Phylogenetic analysis revealed diverse variants from tissues parallel to the viral inoculum in all viral suppressed animals. These results demonstrate that the latency and viral reservoirs in the lymphoid tissues still exist in aviremic macaques under full suppressive therapy. Moreover, the size of viral latent reservoirs differs in various lymphoid tissues with a relatively larger size in the MesLNs.

Background: Binding of HIV to the chemokine coreceptor CXCR4 mediates viral fusion and signal transduction that promotes actin dynamics critical for HIV infection of blood resting CD4 T cells. It has been suggested that this gp120-mediated actin activity resembles the chemotactic actin dynamics mediated by chemokines such as SDF-1. To determine whether inhibiting SDF-1-mediated chemotactic activity can also inhibit HIV infection, we screened several inhibitors known to reduce SDF-1-mediated chemotaxis of T cells.Results: We found that a tyrosine kinase inhibitor, genistein, inhibited both SDF-1-mediated chemotaxis and HIV infection of resting CD4 T cells. Genistein was also found to interfere with SDF-1- and HIV-mediated actin dynamics in CD4 T cells. This reduction in actin activity correlates with genistein-mediated inhibition of viral DNA accumulation in resting CD4 T cells. In addition, we also tested two other tyrosine kinase inhibitors, sunitinib and AG1478. Sunitinib, but not AG1478, inhibited HIV infection of resting CD4 T cells. We further tested the safety of genistein in 3 Chinese rhesus macaques (Macaca mulatta), and each animal was given a monotherapy of genistein at 10 mg/kg orally for 12 weeks. No adverse drug effects were observed in these animals.Conclusions: Our results suggest that novel therapeutic strategies can be developed based on targeting cellular proteins involved in HIV-dependent signaling. This approach can interfere with HIV-mediated actin dynamics and inhibit HIV infection.

Viral reservoirs–persistent residual virus despite combination antiretroviral therapy (cART)–remain an obstacle to cure of HIV-1 infection. Difficulty studying reservoirs in patients underscores the need for animal models that mimics HIV infected humans on cART. We studied SIV-infected Chinese-origin rhesus macaques (Ch-RM) treated with intensive combination antiretroviral therapy (cART) and 3 weeks of treatment with the histone deacetyalse inhibitor, suberoylanilide hydroxamic acid (SAHA). SIVmac251 infected Ch-RM received reverse transcriptase inhibitors PMPA and FTC and integrase inhibitor L-870812 beginning 7 weeks post infection. Integrase inhibitor L-900564 and boosted protease inhibitor treatment with Darunavir and Ritonavir were added later. cART was continued for 45 weeks, with daily SAHA administered for the last 3 weeks, followed by euthanasia/necropsy. Plasma viral RNA and cell/tissue-associated SIV gag RNA and DNA were quantified by qRT-PCR/qPCR, with flow cytometry monitoring changes in immune cell populations. Upon cART initiation, plasma viremia declined, remaining <30 SIV RNA copy Eq/ml during cART, with occasional blips. Decreased viral replication was associated with decreased immune activation and partial restoration of intestinal CD4+ T cells. SAHA was well tolerated but did not result in demonstrable treatment-associated changes in plasma or cell associated viral parameters. The ability to achieve and sustain virological suppression makes cART-suppressed, SIV-infected Ch-RM a potentially useful model to evaluate interventions targeting residual virus. However, despite intensive cART over one year, persistent viral DNA and RNA remained in tissues of all three animals. While well tolerated, three weeks of SAHA treatment did not demonstrably impact viral RNA levels in plasma or tissues; perhaps reflecting dosing, sampling and assay limitations.

Definitive treatment of HIV infection remains a critical but elusive goal, with persistence of residual virus even in the face of prolonged administration of suppressive combination antiretroviral treatment (cART) providing a source for recrudescent infection if treatment is stopped. Characterization of the residual virus and devising strategies to target it for eradication are key goals in HIV treatment research. Indian rhesus macaques (In-RM) infected with SIVmac have been widely used in such research. However, it has proven challenging to achieve and sustain clinically relevant levels of suppression (<30 vRNA copies/ml plasma) with cART in such models. As ease of viral suppression by cART is related to pretreatment levels of viral replication, and levels of replication of SIVmac239/251 are lower in Chinese rhesus macaques (Ch-RM) than in In-RM, we evaluated cART administration to SIVmac-infected Ch-RM as a potential model for studies of residual virus and eradication strategies. Four SIVmac239-infected Ch-RM received cART including reverse transcriptase inhibitors PMPA/FTC and integrase inhibitor L-870812 daily for 8 weeks. Plasma viral loads were promptly reduced to <30 copies/ml upon initiation of cART. Cell-associated SIV DNA levels in lymphocytes from the gut were also significantly reduced. Jejunal and colonic CCR5 ⁺ CD4 ⁺ mucosal memory T cells increased significantly; restoration of these cells was associated with reductions in immune activation. In conclusion, cART effectively suppressed viral replication to <30 vRNA copies/ml in SIVmac239-infected Ch-RM, reducing immune activation and restoring mucosal immune cell populations. SIVmac239-infected Ch-RM may be a useful model for studying responses to cART and persistent tissue reservoirs and evaluating candidate eradication strategies to cure HIV infection.