CROI 2019 Abstract eBook

Abstract eBook

Poster Abstracts

Conclusion: This study highlights the importance of MDMs as a key contributor of persistent T cell infection through their ability to facilitate numerous cell-cell contacts in lymphoid tissues. Our 3D imaging approach allows for T cells to randomly migrate and engage HIV-infected macrophages, modeling their initial encounters and mimicking the main concepts of the same in-situ environment. 222 THE ROLE OF MIGRATORY DENDRITIC CELLS IN ESTABLISHING HIV DISSEMINATION Wan Koh , Paul Gabriel C. Lopez, Ryan Hnatiuk, Umar P. Mohammed, Ajibola Oluwaseun, Thomas Murooka University of Manitoba, Winnipeg, MB, Canada Background: HIV-1 dissemination from the genital mucosal tract to the lymphoid organs is the first critical step towards systemic infection. HIV-1 can disseminate either as free-virus, or it can be transported to lymphoid tissues by migratory cells. Our previous studies strongly argued that the trafficking of cell-associated HIV-1 from the genital mucosa to lymphoid organs played a dominant role in viral spread early after sexual transmission in humanized mice. Here, we further extend these observations by addressing the role of migratory DCs in the capture, retention and transfer of HIV-1 to susceptible T cells through trans-infection, a route of viral transmission that occurs through cell-cell contact. Methods: To characterize the molecular and cellular aspects of DC:T trans- infection, we modeled the dynamics of DC:HIV and DC:T cell interactions within a 3D collagen matrix that recapitulates the stromal networks of the lymph node. Two-photon microscopy was performed to visualize (1) the cellular dynamic of HIV capture and retention by DCs, and (2) the interaction between HIV- bearing DCs and T cells. We used blocking antibodies to dissect the molecular underpinnings of HIV capture by DCs, and the role of adhesion molecules ICAM-1 and LFA-1 in stabilizing DC:T cell contacts during trans-infection. To determine the role chemoattractant receptor-mediated DCs such as S1PR1 and CCR7 play in spreading HIV, we employed transwell chemotaxis assays and live-cell imaging studies of in situ DC migration within explanted mouse ear slices. Results: Mature DCs captured HIV-1 on the cell surface, mediated by Siglec-1, and that captured virus rapidly formed dense clusters near the uropodia of migrating DCs. The chemotactic responses of HIV-1 bearing DCs towards lymph node homing chemokines CCL19/21 and S1P were preserved. HIV-bearing DCs engaged in progressively stable contacts with T cells in 3D collagen, which was a pre-requisite for rapid HIV transmission at the contact site. Consistent with this, HIV-bearing DCs transmitted virus was five-fold more efficient at infected T cells compared to cell-free virus, and that LFA-1:ICAM-1 adhesive contacts played a critical role in this process. Conclusion: DCs retain their ability to migrate into lymph nodes following virus capture, and are able to engage T cells and form stable DC:T cell interactions. This suggests that blocking the movement of HIV+DCs out of the genital mucosa may be a novel approach to restrain virus dissemination and limit systemic viremia. 223 CHARACTERIZATION OF SHIV IMMUNOPATHOGENESIS IN RHESUS MACAQUES Jennifer A. Manuzak 1 , Ernesto Coronado 2 , Tiffany Hensley-McBain 2 , Charlene Miller 1 , Courtney Broedlow 1 , George Shaw 3 , Katharine J. Bar 3 , Nichole Klatt 1 1 University of Miami, Miami, FL, USA, 2 University of Washington, Seattle, WA, USA, 3 University of Pennsylvania, Philadelphia, PA, USA Background: Simian-human immunodeficiency viruses (SHIVs) have been utilized to test vaccine efficacy and characterize mechanisms of transmission and pathogenesis. However, the SHIV model has a significant limitation in that the majority of strains have been created using HIV-1 Env sequences from laboratory-adapted or multiply passaged viruses. Recently, a newly developed SHIV that incorporates the vpu-env(gp140) sequence from a transmitted/ founder HIV-1 subtype C strain (CH505) was shown to retain attributes of primary HIV-1 strains. Here, we characterize the immunopathogenesis of this novel SHIV in peripheral and mucosal tissue of male rhesus macaques. Methods: Male rhesus macaques (n=7) underwent multiple low-dose intra- rectal challenges with SHIV.C.CH505.375H.dCT. Viral challenge was halted when animals tested PCR positive for viral sequences in plasma. Blood, colon and rectum biopsies were collected pre- and post-infection and used to monitor plasma viral load and intestinal immune populations. Results: All animals became productively infected within 6 challenges and exhibited similar acute viral replication kinetics, including a median peak viral

load of 1x10 6 RNA copies/ml plasma (range=0.89x10 6 – 5.5x10 6 ) reached by two weeks post-infection. Set point viral loads ranged from 3.8x10 3 – 0.99x10 6 RNA copies/ml plasma. At week2-post-infection, CCR5+ CD4+ T cells were significantly decreased in both the colon (p=0.01) and the rectum (p=0.001) compared to pre-SHIV infection. The frequency of CCR5+CD4+ T cells remained consistently lower than pre-SHIV infection levels through week8- and week16- post-infection. In addition, by week16-post-infection, there was a significant depletion of CCR6+CD4+ T cells in both the colon (p=0.05) and rectum (p=0.01) compared to pre-SHIV infection. Conclusion: In line with previous findings, we demonstrate that SHIV.C.CH505.375H.dCT is capable of infecting and replicating efficiently in rhesus macaques after low-dose intra-rectal challenge, resulting in peripheral viral kinetics similar to that seen in SIV/HIV infection. Furthermore, our findings indicate that this virus is capable of eliciting intestinal immunopathology typical of SIV/HIV, including decreases in the intestinal frequency of a major cellular target population, CCR5+ CD4+ T cells. These findings affirm the value of this novel SHIV as a tool to evaluate SIV/HIV vaccine efficacy and viral pathogenesis. 224 PLASMA CXCL13 AS A MARKER OF HIV DISEASE PROGRESSION AND SYSTEMIC IMMUNE ACTIVATION Rayoun Ramendra 1 , VikramMehraj 2 , Stéphane Isnard 1 , Bertrand Lebouché 1 , Cecilia Costiniuk 3 , Réjean Thomas 3 , Jason Szabo 3 , Jean-Guy Baril 3 , Benoit Trottier 3 , Pierre Coté 3 , Roger LeBlanc 3 , Cécile Tremblay 3 , Jean-Pierre Routy 3 , for the Montreal Primary HIV-infection Study Group and Canadian HIV and aging cohort 1 McGill University, Montreal, QC, Canada, 2 Centre Hospitalier de l’Université de Montréal, Montreal, QC, Canada, 3 McGill University Health Centre, Glen site, Montreal, QC, Canada Background: CXCL13 is preferentially secreted by Follicular Helper T cells (TFH) to attract B cells to germinal centers. Plasma levels of CXCL13 have been reported to be elevated during chronic HIV-infection, however there is limited data on CXCL13 levels during early phases of infection. Moreover, the contribution of CXCL13 to disease progression and systemic immune activation have been poorly defined. Herein, we assessed the relationship between plasma CXCL13 and validated markers of disease progression. Methods: Study samples were collected in 146 people living with HIV (PLWH) who were in early (EHI) and chronic (CHI) HIV infection and 35 elite controllers (EC) compared to 28 uninfected controls (UC). A subset of 25 progressors were followed prospectively for 2 years, 11 of whom initiated ART. Plasma levels of CXCL13 were compared with CD4 T cell count, CD4/CD8 ratio, plasma viral load (VL), markers of microbial translocation (LPS, sCD14, and LBP), markers of B cell activation (total IgG, IgM, IgA, and IgG1-4), inflammatory cytokines (TNF-α), and immune activation markers (frequency of CD8+CD38+DR+ T cells, and PD-1 expression on CD4+ T cells). Results: Plasma levels of CXCL13 were elevated in EHI (127.9±64.9 pg/mL) and CHI (229.4±28.5 pg/mL) compared to EC (71.3±20.1 pg/mL) and UC (33.4±4.9 pg/mL). Longitudinal analysis demonstrated that CXCL13 was significantly elevated after 24 months without ART (260.5±30.4 pg/mL, p<0.001) and was reduced without normalization 24 months after ART initiation (81.5±10.3 pg/mL, p=0.002). CXCL13 correlated positively with VL (r=0.390; p<0.001), negatively with CD4 T cell count (r=-0.298; p<0.001), CD4/CD8 ratio (r=-0.359; p<0.001), positively with markers of microbial translocation LPS (r=0.225; p=0.007) and sCD14 (r=0.260; p=0.03), markers of B cell activation total IgG (r=0.422; p=0.003), IgG1 (r=0.276; p=0.05), TNF-α (r=0.280; p<0.001), frequency of CD38+HLA-DR+ CD8 T cells (r=0.543; p=0.008) but not CD38+HLA-DR+ CD4 T cells (r=0.287; p=0.366), and PD-1 expression on CD4 T cells (r=-0.460; p=0.03). Conclusion: Plasma CXCL13 levels increased during HIV disease progression. Early initiation of ART may reduce plasma CXCL13 and B cell activation without normalization. CXCL13 represents a novel marker of HIV disease progression and inflammation at the early and chronic phases of the infection, and may be a predictor of non-AIDS events. 225 MODULATION AND PATHOGENESIS OF HIV-1 X4 EVOLUTION IN DISEASE PROGRESSION Li Yin 1 , Wilton B. Williams 2 , Amanda C. Lowe 3 , Kai-Fen Chang 1 , John W. Sleasman 2 , Maureen Goodenow 1

Poster Abstracts

79

CROI 2019