An effective vaginal microbicide could reduce human immunodeficiency virus type 1 (HIV-1) transmission to women. Among microbicide candidates in clinical development is Maraviroc (MVC), a small molecule drug that binds the CCR5 co-receptor and impedes HIV-1 entry into cells. Delivered systemically, MVC reduces viral load in HIV-1-infected people, but its ability to prevent transmission is untested. We have now evaluated MVC as a vaginal microbicide, using a stringent model involving challenge of rhesus macaques with a high-dose of a CCR5-using virus, SHIV-162P3. Gel-formulated, prescription-grade MVC provided dose-dependent protection, half-maximally at 0.5 mM (0.25 mg/ml). The duration of protection was transient; the longer the delay between MVC application and virus challenge, the less protection (T1/2 ~ 4 h). As expected, MVC neither protected against challenge with a CXCR4-using virus, SHIV-KU1, nor exacerbated post-infection viremia. These findings validate MVC development as a vaginal microbicide for women, and should guide clinical programs.

SUMMARY Innate lymphoid cells (ILCs) are an emerging subset of lymphocytes involved in surveillance against virally infected cells. Here we show CD3−CD8high lymphocytes in macaque blood include major subsets of ILCs including NK cells expressing CD16, NKp46 and NKG2A, but also populations of ILCs in mucosal tissues having different properties. One ILC subset secreted IL-17 (ILC17), but these were restricted to mucosal tissues. Some mucosal ILC17 cells expressed classical NK-cell markers, but little NKG2A or NKG2D. Some ILC17 cells secreted IL-22 and TNF-α, but few produced IFN-γ or contained granzyme B. IL-17 production by ILCs was induced by IL-6, TGF-β and IL-23. Further, SIV infection resulted in a significant loss of ILC17 cells, especially in the jejunum, which persisted throughout SIV infection. These findings ILC17 cells may be involved in innate mucosal immune responses, and their loss may contribute to loss of intestinal mucosal integrity and disease progression in HIV/SIV infection.

IntroductionRapid and profound loss of "activated" memory CD4 ϩ T cells, particularly in the intestine, is a hallmark of both HIV and simian immunodeficiency virus (SIV) infection. However, the mechanism by which CD4 ϩ T cells are eliminated in early infection remains obscure. Furthermore, infants usually have a more rapid and severe course of disease, with persistently higher viral loads than adults with HIV infection. [1][2][3][4][5] Because neonates are believed to be born with mostly "naive" T cells, why would HIV infection be more severe in infants, who have far fewer of the "activated" memory CD4 ϩ T cells required to fuel viral replication?It is well established that the intestinal tract is a major site of early HIV/SIV infection in adults 6-10 and prior studies in SIVinfected neonates showed that as in adults, intestinal CD4 ϩ T cells are also the major target for early pediatric SIV infection. 11,12 Furthermore, most intestinal CD4 ϩ T cells in the intestinal lamina propria of normal neonatal macaques already have an "activated, memory" phenotype, even on the day of birth, despite not having encountered environmental antigens outside the womb. 11 This suggests that neonates have ample target cells to support HIV infection and amplification, even prior to birth, and that these intestinal cells may be capable of mounting functional immune responses. However, absolute numbers and percentages of these target cells are far fewer in neonates than adults, so this alone cannot explain the higher viral loads in infected neonates. Because neonates are immediately exposed to a variety of new environmental antigens after birth, we hypothesized that increased activation, infection, and perhaps most importantly, a more sustained turnover of viral target cells in neonatal intestines could potentially explain why neonates have sustained viral loads and accelerated disease progression.To date, information on T-cell turnover rates is limited to peripheral blood, and few studies have examined proliferation and T-cell turnover in tissues, particularly the intestinal tract, the primary target for acute SIV and HIV infection. Furthermore, little data on mucosal immune responses to HIV or SIV infection of neonates have been published. To monitor proliferation of cell subsets in tissues, we administered bromodeoxyuridine (BrdU) to neonates 24 hours prior to tissue collection. Because BrdU is a thymidine analog incorporated only by cells synthesizing DNA, this method allows for detection of cells in the synthesis phase (S-phase) of cell division. Proliferation rates of T-cell subsets were compared in the blood, lymph nodes, spleen, and intestines of adult and pediatric macaques, as well as pediatric macaques infected with SIVmac251 and age-matched uninfected controls. Methods Animals, virus, and BrdU inoculationTissues from 23 infected and 20 age-matched uninfected neonatal rhesus macaques (Macaca mulatta) were obtained from the Tulane National Primate Research Center. All monkeys were housed and maintained in accordance with t...

Suppression of dendritic cell function in HIV-1 infection is thought to contribute to inhibition of immune responses and disease progression, but the mechanism of this suppression remains undetermined. Using the rhesus macaque model, we show B7-H1 (PD-L1) is expressed on lymphoid and mucosal dendritic cells (both myeloid DC and plasmacytoid DC) and its expression significantly increases after SIV infection. Meanwhile, its receptor, PD-1 is upregulated on T cells in both peripheral and mucosal tissues, and maintained at high levels on SIV-specific CD8+ T cell clones in chronic infection. However, both B7-H1 and PD-1 expression in SIV controllers was similar to controls. Expression of B7-H1 on both peripheral mDCs and pDCs positively correlated with levels of PD-1 on circulating CD4+ and CD8+ T cells, viremia and declining peripheral CD4+ T cells levels in SIV-infected macaques. Importantly, blocking DCs B7-H1 interaction with PD-1+ T cells could restore SIV-specific CD4+ and CD8+ T cell function as evidenced by increased cytokine secretion and proliferative capacity. Combined, the results indicate interaction of B7-H1/PD-1 between APCs and T-cell correlates with impairment of CD4+T-helper cells and CTL responses in vivo, and all are associated with disease progression in SIV infection. Blockade of this pathway may have therapeutic implications for HIV-infected patients.

Expression of tight junction proteins between brain microvascular endothelial cells (BMECs) of the blood-brain barrier (BBB) is lost during development of HIV encephalitis (HIVE). While many studies have focused on the strains of virus that induce neurological sequelae or on the macrophages/ microglia that are associated with development of encephalitis, the molecular signaling pathways within the BMECs involved have yet to be resolved. We have previously shown that there is activation and disruption of an in vitro BBB model using lentivirus-infected CEMx174 cells. We and others have shown similar disruption in vivo. Therefore, it was of interest to determine if the presence of infected cells could disrupt intact cerebral microvessels immediately ex vivo, and if so, which signaling pathways were involved. Our data demonstrate that disruption of tight junctions between BMECs is mediated through activation of focal adhesion kinase (FAK) by phosphorylation at TYR-397. Inhibition of FAK activation is sufficient to prevent tight junction disruption. Thus, it may be possible to inhibit the development of HIVE by using inhibitors of FAK.