CROI 2015 Program and Abstracts

Abstract Listing

Poster Abstracts

healthy, SIV-uninfected RM, we observe a negative correlation between frequencies of T FR cell proliferation (p=0.0315). Following SIV infection, the ratio of T FR to T FH within the total CD4 T cell pool. Finally, we examined whether higher levels of direct virus infection of T FR cells and both T and T REG cells sorted from SIV- infected RM harbor comparable levels of cell-associated viral DNA. found that T FH , T FR

FH (p=0.0358) and GC B cells (p=0.0140) as well as with levels of CD4 + T

cells was reduced (p=0.0058) with no change in the frequency of T REG

cells or in the frequency of T FR

cells

cells might be involved in their relative depletion post-SIV infection. We

Conclusions: Our data suggests that T FR infection of RMmay lead to unchecked expansion of both T FH

cells may contribute to the regulation and proliferation of T FH

and GC B cells in vivo and that a decreased ratio of T FR/ T FH

cells in chronic SIV

and GC B cells.

THURSDAY, FEBRUARY 26, 2015 Session P-C13 Poster Session

Poster Hall

2:30 pm– 4:00 pm Dissecting Pathogenesis Through In Vitro Studies 327 A Dual-Tropic HIV-1 Env Interacts With CCR5 to Deplete Bystander CD4 T Cells In Vitro and In Vivo Li-Chung Tsao 1 ; Haitao Guo 2 ; Jerry Jeffrey 3 ; James A. Hoxie 4 ; Lishan Su 2 1 University of North Carolina, Carrboro, NC, US; 2 University of North Carolina, Chapel Hill, NC, US; 3 GSK, Chapel Hill, NC, US; 4 University of Pennsylvania, Philadelphia, PA, US

Background: Bystander CD4 T cell depletion during HIV-1 infection plays an important role in AIDS disease progression, a process is largely mediated by the HIV-1 Env protein. CCR5 is one of the two co-receptors required for HIV-1 binding and subsequent entry, but its involvement in Env-induced pathogenesis is poorly understood. In this report, we study the CD4 T cell pathogenesis caused by a dual-tropic HIV-1 virus R3A Env, focusing on the role of Env-CCR5 binding. Methods: Using a cultured PBMC infection model or humanized mice in vivo, R3A can readily induce both infected CD4 T cell death and uninfected “bystander” CD4 T cell death. To study the involvement of Env-CCR5 binding, we utilized an Env-mutant of R3A, termed R3A-5,6AA, which has lost the potential for CCR5 binding. Results: We found loss of CCR5-binding by the mutant R3A-5,6AA resulted in reduced pathogenesis of bystander CD4 T cells. Importantly, R3A-5,6AA can replicate to the same level as wild type R3A by using CXCR4-binding for virus entry. Accordingly, treatment of CCR5 antagonist TAK-779 inhibited bystander CD4 T cell death in R3A infection without affecting viral replication. In addition, stimulation of CCR5 using MIP1- β in R3A-5,6AA infection increases bystander CD4 T cell death. We have further confirmed our finding in vivo using a humanized mice model, and we observed bystander CD4 T cell pathogenesis in the spleen and bone marrow is dependent on CCR5 usage by the HIV-1 Env. Conclusions: We provide the first evidence in physiologically relevant in vivo models that shows CCR5 binding by HIV-1 Env plays an important role in Env-induced depletion of bystander CD4 T cells. 328 Investigation of the Association of Gag-Protease Dependent Replication Capacities With Clinical Outcomes of HIV-1 Infection Keiko Sakai 1 ;Takayuki Chikata 1 ; Hiroyuki Gatanaga 2 ; Shinichi Oka 2 ; MasafumiTakiguchi 1 1 Kumamoto University, Kumamoto-shi, Japan; 2 National Center for Global Health and Medicine, Tokyo, Japan Background: Immune pressure by cytotoxic T lymphocytes (CTLs) induces escape mutations and immune evasion in HIV-1 infection, and the persistence of escape variants shapes HLA-associated viral diversity at the population level. Previous studies with Caucasian and African cohorts showed that HLA-associated Gag polymorphisms impose fitness cost and that Gag-Protease mediated viral replication capacity (Gag-Pro RC) is compromised in patients with protective HLA alleles. However, the protective alleles reported in Caucasian/ Africa cohorts, including B*57:01, are not prevalent in Japan. Therefore, factors associated with protection are likely to be different in Asian populations due to different HLA distributions. Moreover, the role of Gag in HIV-1 disease progression has not been well defined in the Asian populations. To address these issues, we investigated HLA-associated carrying gag-protease derived from 330 treatment-naive Japanese individuals who are chronically infected with HIV-1 subtype B. Replication capacities of chimeric viruses were determined by infecting CEM-GXR cells in vitro , which are engineered to express LTR-GFP, CCR5, and CXCR4. Subsequently, we examined the association of Gag-Pro RCs with clinical markers of HIV infection and the impact of patients’ HLA alleles on Gag-Pro RCs. Results: In contrast to Caucasian- and African-cohort studies, patients with higher Gag-Pro RCs showed only a weak tendency toward higher viral load (VL) and lower CD4 count. We did not observe statistically significant associations. Even though previous studies with Caucasian and African cohorts reported a stronger association of Gag-Pro RCs with patients’ VL in the presence of protective HLA alleles such as HLA-B*57, our data indicated that subjects who did not carry Japanese-specific protective alleles, HLA-B*52 and -B*67, showed a statistically significant association between Gag-Pro RCs and VL. Furthermore, we found six locations in the Gag-Protease region, four of which was negatively correlated and the other two positively correlated with VL. Conclusions: Taken together, our data suggested the impact of Gag-Pro dependent replication on HIV-1 disease progression in the absence of a protective immune pressure. The results also implied a different mechanism of HLA-induced changes in Gag-Pro RCs and their impact on clinical outcomes in the Japanese population compared to Caucasian and African cohorts. 329 Association of Bacteria-Induced IL-23 and Th17 Frequencies in HIV-1 + Individuals Jennifer Manuzak 1 ; Sonia Amraoui 1 ; Nipa Decroix 2 ; Pierre Loulergue 2 ; Odile Launay 2 ; Marco Iannetta 1 ; Jean-Baptiste Guillerme 1 ; LeneVimeux 1 ; Anne Hosmalin 1 1 Inserm U1016, Institut Cochin, Paris, France; 2 Centre d’Investigation Clinique CIC 1417, Inserm-AP-HP, Hôpital Cochin, Paris, France Background: Cytokine imbalances in HIV-1 infection could be mediated in part by the innate immune response to translocated intestinal microbes. Previous work showed that PBMC from HIV-1-infected patients (HIV-1 + ) produce significantly more IL-23 in response to bacterial stimulation as compared to uninfected controls (HIV-1 - ). Overproduction of IL-23 could skew T cell responses towards a Th17 phenotype. However, the relationship between microbial translocation, cytokine production and Th17 cell frequencies in the context of in vivo HIV-1 infection is not well understood. We compared IL-23 production and the frequency of Th17 cells in response to bacterial stimulation during HIV infection. Methods: PBMC from 18 chronically infected HIV-1 + and 21 HIV-1 - donors were utilized. The frequency of Th17 cells (IL-17A + IFN- γ - ) within memory CD4 + T cells (CD3 + CD4 + CD45RA - ) of total PBMC was assessed either ex vivo on fresh PBMC or in vitro after stimulation with E. coli or P. aeruginosa using frozen PBMC by multi-parameter flow cytometry. Levels of IL-23 in PBMC culture supernatants after bacterial stimulation were assessed by ELISA. Statistical significance between the HIV-1 + and HIV-1 - groups was assessed using Mann- Whitney tests. Correlations were calculated using Pearson tests. changes in Gag-Pro RCs in a Japanese cohort. Methods: We generated chimeric HIV-1NL 4-3

Poster Abstracts

260

CROI 2015