CROI 2018 Abstract eBook

Abstract eBook

Poster Abstracts

lymph nodes and also found a substantial frequency of CD4+ CXCR5+ effector T cells in samples from HIV+ individuals. Importantly, the expansion of these cells after SEB stimulation was elevated in comparison to TFCs in lymph nodes and tonsils from healthy controls or blood samples from chronic HIV+ individuals. Using immunofluorescence microscopy we determined an enrichment of TFCs in the B cell follicle confirming their follicular homing. We next determined their ability to kill virally infected cells and found that similar to regular CTL CD4+ T cells, these cells showed enhanced ability to recognize and kill infected cells. Conclusion: In conclusion, we demonstrate a novel subset of cytolytic CD4+ T cells with follicular homing properties that can be found in the B cell follicle and shows enhanced viral inhibitory activity. Harnessing this cellular subset through therapeutic intervention may provide a novel strategy for HIV eradication attempts. 287 TFC CELLS INTERACT WITH OTHER FOLLICULAR T CELLS TO CONTROL SIV VIREMIA Mohammad Arif Rahman 1 , Katherine M. McKinnon 1 , Tatiana S. Karpova 1 , David A. Ball 1 , David Venzon 2 , Wenjin Fan 3 , Guobin Kang 3 , Qingsheng Li 3 , Marjorie Robert-Guroff 1 1 NIH, Bethesda, MD, USA, 2 NIH, Rockville, MD, USA, 3 University of Nebraska–Lincoln, Lincoln, NE, USA Background: B cell follicles, which may not be accessible to ART or antiviral CD8+ T cells, are considered an immune privileged site for HIV/SIV replication. However, recent evidence suggests follicular cytotoxic T cells (Tfc) can locate to B cell follicles of secondary lymphoid tissue and might contribute to viremia control. Here we aimed to clarify the role of viral-specific Tfc cells in lymph nodes (LNs) over the course of SIV infection in rhesus macaques. Methods: LN biopsy specimens were collected from naïve and acutely and chronically (low viral load, LVL; and high viral load, HVL) SIV-infected rhesus macaques. Assays performed to clarify the interaction of Tfc cells with other LN follicular T cells and assess their impact on disease course included: immunohistochemistry to localize Tfc and Tfh cells; flowcytometry to determine the frequency of Tfc, Tfh and T follicular regulatory (Tfreg) cells and SIV-specific cytokine production; ELISPOT using sorted cells to quantify SIV-specific Tfc; a flowcytometry based killing assay to evaluate the functionality of sorted Tfc cells. Results: Tfc and Tfh cells were localized in LN B cell follicles. Positive correlations between percentages of these cells were observed in acute (r=0.55, p=0.022) and LVL (r=0.60, p=0.0073) but not HVL animals. SIV-specific Tfc cell frequencies were comparable between HVL and LVL animals, however, LVL animals tended to express more Gag-specific granB, exhibited greater killing than HVL animals (p=0.008), and their Tfc cell frequencies negatively correlated with viremia (r=-0.63, p=0.04). In LVL but not HVL animals, Tfh and Tfc cells correlated directly (r=0.63, p=0.04). Env- and Gag-specific IL-21+Tfh of LVL but not HVL macaques negatively correlated with viral load (r=-0.65, p=0.036; r=-0.67, p=0.028, respectively), suggesting better provision of T cell help to Tfc. In LVL animals Tfreg and Tfc cells were positively correlated (r=0.74, p=0.013) and negatively correlated with viremia (r=-0.81, p=0.0033), perhaps due to suppression of chronic inflammation. In contrast, Tfreg and Tfc cell frequencies of HVL macaques tended to negatively correlate (r=-0.57, p=0.071). A positive correlation was seen between Tfreg cell number in HVL macaques and viremia (r=0.65, p=0.034), suggesting dysfunction and suppression of an effective Tfc immune response. Conclusion: Our results indicate that control of virus-infected cells in B cell follicles not only depends on Tfc cell cytotoxicity but also on Tfc cell interaction with Tfh and Tfreg. 288 CHARACTERIZATION OF THE NEUTRALIZING ANTIBODY RESPONSE IN A LINKED HIV SUPERINFECTION Deogratius Ssemwanga 1 , Nicole Doria-Rose 2 , Andrew D. Redd 3 , Andrea R. Shiakolas 2 , Andrew Longosz 3 , Rebecca N. Nsubuga 1 , Gershim Asiki 4 , Janet Seeley 4 , Amy Ransier 2 , Sam Darko 2 , Daniel Douek 2 , Stephen Porcella 2 , Thomas C. Quinn 3 , John R. Mascola 5 , Pontiano Kaleebu 4 1 Medical Research Council, Entebbe, Uganda, 2 NIAID, Bethesda, MD, USA, 3 NIAID, Baltimore, MD, USA, 4 MRC Uganda Virus Research Institute, Entebbe, Uganda, 5 Vaccine Research Center, NIAID, Bethesda, MD, USA Background: HIV-superinfection (HIV-SI) occurs when an infected individual acquires a new HIV strain that is phylogenetically distinct from their existing viral population. HIV-SI provides an opportunity to examine the potential role of

pre-existing HIV-specific neutralizing antibodies (NAb) in protecting against a subsequent HIV challenge. Methods: Virally unlinked HIV+ individuals in monogamous (n=15) and polygamous relationships (n=6) from the Rural Clinical Cohort (RCC) in southwest Uganda were tested for occurrence of HIV-SI using a previously validated next-generation sequencing (NGS) assay of three viral genomic regions (gag, pol, gp41). One case of linked HIV-SI was identified, and for this case serum samples from before and after the time of the HIV-SI event for both the female, and her husband, were subjected to single-genome amplification (SGA) to generate full-envelope sequences. Full-length Env amplicons from SGA were used to generate pseudoviruses that were tested for their neutralization susceptibility to their homologous serum, as well as their partner’s heterologous serum from before and after HIV-SI. Results: The linked HIV-SI occurred in a polygamous relationship in which an HIV-infected uncircumcised male superinfected one of his four wives who were all HIV-positive. The male had no indication of HIV-SI in any of the sequences examined. Full-length viral envelope sequences were obtained from the female partner immediately before HIV-SI (Month 0, n=21) and when HIV-SI was first detected three months later (Month +3, n=10). Three of the viral sequences from this later sample were phylogenetically linked to the male’s viruses, thus representing the superinfecting strain. The female’s serum samples prior to HIV-SI displayed moderate NAb activity against her homologous virus. However, her serum prior to HIV-SI, and immediately post HIV-SI, contained no detectable NAb activity to the superinfecting strain. Ten months post HIV-SI, the female had developed a moderate response to the superinfecting strain. Conclusion: A linked HIV-SI event occurred in a chronically infected female who had moderately potent and broad anti-HIV NAb responses. Despite this, she possessed no detectable NAb response to the superinfecting strain during the estimated HIV-SI window, which potentially could have protected her. This unique case highlights the exciting amount of potential information that even a small number of these linked HIV-SI events could provide. 289 BROAD SPECTRUM OF NEUTRALIZATION-ENHANCEMENT BY NOVEL CD4MIMIC COMPOUND YIR-821 Shokichi Takahama 1 , Kazuki Tanaka 1 , Hasan Zahid 1 , AlamMuntasir 2 , Takeo Kuwata 1 , Ami Masuda 3 , Kohei Takahashi 3 , Takuya Kobayakawa 3 , Takuya Yamamoto 4 , Tomoyuki Miura 5 , Liye He 6 , Hirokazu Tamamura 3 , Shilei Ding 7 , Andrés Finzi 7 , Shuzo Matsushita 1 1 Kumamoto University, Kumamoto, Japan, 2 International Centre for Diarrhoeal Disease Research, Dhaka, Bangladesh, 3 Tokyo Medical and Dental University, Tokyo, Japan, 4 National Institutes of Biomedical Innovation, Health and Nutrition, Osaka, Japan, 5 Kyoto University, Kyoto, Japan, 6 Institute for Molecular Medicine Finland, Helsinki, Finland, 7 Centre de Research du Centre Hospitalier de l’Université de Montreal, Montreal, QC, Canada Background: CD4 mimic compounds (CD4mc) that inhibit the interaction of gp120 with CD4 are expected as an entry inhibitor. Furthermore, CD4mc induce structural changes in gp120 trimer through binding to the CD4 binding (Phe43)- cavity of gp120. We recently developed YIR-821, a novel CD4mc, which showed more potent and less cytotoxic activities than original CD4mc NBD-556. Here we examined anti-HIV-1 activities of YIR-821 including enhancing activities for neutralization and ADCC (antibody-dependent cellular cytotoxicity) against a variety of viruses. Methods: We used pseudovirus panels of HIV-1 strains (standard panel B/ panel C/global standard panel) to investigate the spectrum of YIR-821 for neutralization/binding enhancement as well as activities as an entry inhibitor. Synergistic effects in neutralization were examined for antibodies targeting V3/CD4bs/CD4i regions and calculated by R package “SynergyFinder”. To evaluate ADCC, CEM-NKR-CCR5-luc T-cell line infected with HIV-1 BaL was prepared as target and incubated with antibodies and effector cells (CD16 expressing KHYG-1 NK cell line) for 8 hours, then relative luminescent activity was measured. Results: We found broad and potent anti-HIV-1 activities of YIR-821 as an entry inhibitor against panels of subtype-B and C virus. YIR-821 induced exposure of conformational epitopes on gp120 was observed not only in subtypes B and C, but also subtypes A and B/C, which were relatively resistant to the inhibitory activity by YIR-821. Interestingly, YIR-821 treatment alone is not effective against JR-FL (subtype B, but uniquely YIR-821 resistant strain), but the combination of YIR-821 with anti-V3/CD4i antibodies showed synergistically neutralization, suggesting some difference in the process of these two anti-HIV

Poster Abstracts

CROI 2018 101