Evidence for an increased risk of transmission of simian immunodeficiency virus and malaria in a rhesus macaque coinfection model.

In sub-Saharan Africa, HIV-1 infection frequently occurs in the context of other coinfecting pathogens, most importantly, Mycobacterium tuberculosis and malaria parasites. The consequences are often devastating, resulting in enhanced morbidity and mortality. Due to the large number of confounding factors influencing pathogenesis in coinfected people, we sought to develop a nonhuman primate model of simian immunodeficiency virus (SIV)-malaria coinfection. In sub-Saharan Africa, Plasmodium falciparum is the most common malaria parasite and is responsible for most malaria-induced deaths. The simian malaria parasite Plasmodium fragile can induce clinical symptoms, including cerebral malaria in rhesus macaques, that resemble those of P. falciparum infection in humans. Thus, based on the well-characterized rhesus macaque model of SIV infection, this study reports the development of a novel rhesus macaque SIV-P. fragile coinfection model to study human HIV-P. falciparum coinfection. Using this model, we show that coinfection is associated with an increased, although transient, risk of both HIV and malaria transmission. Specifically, SIV-P. fragile coinfected macaques experienced an increase in SIV viremia that was temporarily associated with an increase in potential SIV target cells and systemic immune activation during acute parasitemia. Conversely, primary parasitemia in SIV-P. fragile coinfected animals resulted in higher gametocytemia that subsequently translated into higher oocyst development in mosquitoes. To our knowledge, this is the first animal model able to recapitulate the increased transmission risk of both HIV and malaria in coinfected humans. Therefore, this model could serve as an essential tool to elucidate distinct immunological, virological, and/or parasitological parameters underlying disease exacerbation in HIV-malaria coinfected people.

Efficacy of NNRTI-based antiretroviral therapy initiated during acute HIV infection.

OBJECTIVE: Characterize responses to non-nucleoside reverse transcriptase inhibitor (NNRTI)-based antiretroviral treatment (ART) initiated during acute HIV infection (AHI). DESIGN: This was a prospective, single-arm evaluation of once-daily, co-formulated emtricitabine/tenofovir/efavirenz initiated during AHI. METHODS: The primary endpoint is the proportion of responders with HIV RNA less than 200 copies/ml by week 24. We examined time to viral suppression and CD8 cell activation in relation to baseline participant characteristics. We compared time to viral suppression and viral dynamics using linear mixed-effects models between acutely infected participants and chronically infected controls. RESULTS: Between January 2005 and May 2009, 61 AHI participants were enrolled. Of participants whose enrollment date allowed 24 and 48 weeks of follow-up, 47 of 51 (92%) achieved viral suppression to less than 200 copies/ml by week 24, and 35 of 41 (85.4%) to less than 50 copies/ml by week 48. The median time from ART initiation to suppression below 50 copies/ml was 93 days (range 14-337). Higher HIV RNA levels at ART initiation (P = 0.02), but not time from estimated date of infection to ART initiation (P = 0.86), were associated with longer time to viral suppression. The median baseline frequency of activated CD8+CD38+HLA-DR+ T cells was 67% (range 40-95), and was not significantly associated with longer time to viral load suppression (P = 0.15). Viremia declined to less than 50 copies/ml more rapidly in AHI than chronically infected participants. Mixed-model analysis demonstrated similar phase I HIV RNA decay rates between acute and chronically infected participants, and more rapid viral decline in acutely infected participants in phase II. CONCLUSION: Once-daily emtricitabine/tenofovir/efavirenz initiated during AHI achieves rapid and sustained HIV suppression during this highly infectious period.