CROI 2018 Abstract eBook

Abstract eBook

Poster Abstracts

Conclusion: HIV-ASCT individuals showed comparable peripheral blood recovery of CD4 T-cells, but increased numbers of CD8 T-cells post-ASCT – with detailed flow cytometry showing that the subsets that make up these elevated CD8 T cells appear to vary between subjects. The FNB data suggests that, compared with non-ASCT controls, nodal CD4 T cell recovery is impaired, even several years post-ASCT. While subject numbers are limited, the differences seen here suggest that co-infections and HIV associated factors, such as pre-existing immune impairment, may impact immune reconstitution.

decreased and there were no differences in the response to gag peptides. At necropsy (~20 weeks post-infection), VRC01-Rh-α4β7-treated macaques had significantly more IFNγ-producing T cells in the gut. Differences in T cell subsets in inguinal lymph nodes were present in both treatment groups compared to the controls. Conclusion: The combination of VRC01 and Rh-α4β7 decreased chronic viral load and altered immune responses against SHIV-AD8. Further exploration of the effect of combining other bNAbs with Rh-α4β7 on SIV/HIV infection is warranted and may lead to novel preventive and therapeutic strategies. Sushama Telwatte 1 , Sulggi Lee 1 , Ma Somsouk 1 , Hiroyu Hatano 1 , Christopher Baker 1 , Peggy Kim 2 , Tsui-Hua Chen 1 , Jeffery Milush 1 , Peter W. Hunt 1 , Steven G. Deeks 1 , Joseph K. Wong 2 , Steven A. Yukl 2 1 University of California San Francisco, San Francisco, CA, USA, 2 San Francisco VA Medical Center, San Francisco, CA, USA Background: The gut is a critical site for HIV replication and persistence. Tissue-specific environments likely impact the size and activity of the reservoir. We hypothesized that the mechanisms and degrees of HIV transcriptional blocks underlying HIV latency differ between the gut and blood. Methods: We investigated the mechanisms that inhibit HIV transcription in vivo using a validated panel of RT-ddPCR assays to quantify HIV transcripts suggestive of transcriptional interference (U3-U5; “read-through”), initiation (TAR), elongation (R-U5-tRNA; “long LTR”), distal transcription (nef), completion (U3-polyA; “polyA”), and multiple splicing (tat-rev). Total RNA and DNA were extracted frommatched FACS-sorted CD4+T cells from blood and rectum (n=7) and frommatched PBMCs and rectal biopsies (n=9); all samples were obtained from individuals on effective ART. Levels of each transcript were quantified and expressed as absolute copies/10^6 cells (normalized to a reference gene), ratios of each transcript to total (TAR) and processive (long) transcripts, and average transcription levels per provirus (HIV RNA/DNA). Results: Rectal biopsies showed low levels of read-through transcripts (median=23 copies/10^6 cells) and a gradient of total (679)>elongated (75)>nef (16)>polyA (11)>multiply-spliced HIV RNAs (<1) [p<0.05 for all comparisons], demonstrating blocks to HIV transcriptional elongation, completion and splicing. Levels of total (TAR) transcripts per CD4+T cell and per provirus were significantly lower in the rectum compared to blood (median 2.7 vs. 31.8, p=0.016; and 3.5 vs. 15.4, p=0.008; respectively), indicative of lower HIV transcription initiation in the rectum. The ratio of total to elongated transcripts in CD4+T cells was 6-fold lower in rectum than blood (p=0.016), suggesting less of a block to HIV transcriptional elongation in the rectum. There was also a trend toward a lower ratio of read-through/elongated transcripts in rectal CD4+T cells (p=0.078), suggesting less transcriptional interference. Conclusion: The blood and gut differ in relative contributions of mechanisms governing HIV transcription/latency, with a greater block to HIV transcriptional initiation in the gut (not due to transcriptional interference) but less block to elongation. These mechanistic differences may reflect tissue-specific variation in host gene expression, viral sequences, and/or extracellular milieu and are important to consider in designing therapies that aim to eliminate latent cells in all tissue compartments. Background: CD4+ T cells latently infected with HIV are difficult to eliminate due to minimal expression of HIV antigens. Reservoir clearance may require activation of latent HIV. Agonists of pattern recognition receptors (PRRs) stimulate innate immunity and can induce T cell activation. Several studies indicate that innate immunity activators can induce latent HIV in various in vitro models, but to date there has not been a systematic study of their activity in cells isolated directly from ART-suppressed HIV infected individuals. Methods: Peripheral blood mononuclear cells (PBMCs) or CD4+ T cells were isolated from ART-suppressed HIV-infected donors and treated with a panel of agonists known to stimulate specific PRRs. Pairwise combinations of active agonists were also evaluated. Cytokine production was assessed 24 hours after treatment initiation. HIV RNA in culture supernatants was assessed by

320 TRANSCRIPTIONAL BLOCKS UNDERLYING HIV LATENCY DIFFER BETWEEN GUT AND BLOOD IN VIVO

Poster Abstracts

319LB Α4Β7-BLOCKADE COMBINED WITH VRC01 MODULATES IMMUNE RESPONSES TO SHIV-AD8 INFECTION

Giulia Calenda 1 , Ines Frank 1 , Geraldine Arrode-Bruses 1 , Amarendra Pegu 2 , Wang Keyun 2 , James Arthos 3 , Claudia Cicala 3 , Brooke Grasperge 4 , James Blanchard 4 , Olga Mizenina 1 , Agegnehu Gettie 5 , Anthony S. Fauci 3 , John R. Mascola 2 , Elena Martinelli 1 1 Population Council, New York, NY, USA, 2 Vaccine Research Center, NIAID, Bethesda, MD, USA, 3 NIAID, Bethesda, MD, USA, 4 Tulane National Primate Research Center, Covington, LA, USA, 5 Aaron Diamond AIDS Research Center, New York, NY, USA Background: Passive transfer of VRC01, the first in a family of a new generation of broadly anti-HIV neutralizing antibodies (bNAb), protects macaques from SHIV acquisition. However, protection against repeated challenges rapidly decreases with decreased antibody availability. Infusion of a simianized anti-α4β7 mAb (Rh-α4β7) just prior to, and during repeated vaginal exposures to SIVmac251 protected macaques from vaginal SIV acquisition. Methods: To determine if addition of Rh-α4β7 would increase the protective activity of VRC01, 3 groups of animals were treated with 1) VRC01-alone or 2) a combination of VRC01 + Rh-α4β7 or 3) control antibodies prior to the initiation of weekly vaginal exposures to SHIV-AD8. Inoculations with Rh-α4β7 continued every 3 weeks through the acute and early-chronic phase of infection. Results: Rh-α4β7 did not increase the protective effect of VRC01 against SHIV-AD8 acquisition. However, VRC01-Rh-α4β7-treated animals had a viral set-point 1 Log 10 lower, on average, than animals receiving VRC01 alone. Moreover, the inclusion of Rh-α4β7 provided complete protection of blood CD4 T cell counts. While rectal SIV-DNA loads were slightly higher in VRC01-pre- treated animals from both VRC01-groups around 4 weeks post-infection, they significantly decreased over time in Rh-α4β7-treated animals compared to the controls. No significant differences were noted in SIV DNA and RNA loads in other tissues at necropsy. Interestingly, VRC01-Rh-α4β7-treated macaques had fewer IL-17 producing cells in blood and rectal tissue during the acute phase of infection than the controls. Moreover, blood T cells from the VRC01-Rh-α4β7 group released more IFNγ in response to peptides derived from the 2nd variable loop (V2-loop) of the SHIV-AD8 envelope compared to the other 2 groups. In contrast, T cell responses to a pool of envelope consensus B peptides were

321 PATTERN RECOGNITION RECEPTOR AGONISTS INDUCE HIV IN ART SUPPRESSED HIV+ DONOR CELLS Jasmine Kaur , Angela Tsai, George Kukolj, Tomas Cihlar, Jeffrey Murry Gilead Sciences, Inc, Foster City, CA, USA

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