CROI 2015 Program and Abstracts

Abstract Listing

Poster Abstracts

an attachment inhibitor and blocks viral infection by other mechanism. The further characterization of its mechanism of action and optimization of SC12 will yield important basic information about the process of HIV-1 entry and potentially lead to the novel therapies. 213 Optimization of vCCL2-Based CXCR4 Inhibitors by Phage Display and Rational Design Virginie Fievez 1 ; Martyna Szpakowska 1 ; Karthik Arumugam 1 ; Amor Mosbah 2 ; Sabrina Deroo 1 ; Xavier Dervillez 1 ; Pierre-Arnaud Gauthier 1 ; Michele Baudy-Floc’h 2 ; Carole Devaux 1 ; Andy Chevigné 1 1 CRP-sante, Laboratory of Retrovirology, 84 Rue Val Fleuri, 1526 Luxembourg, Luxembourg; 2 Université de Rennes 1, UMR CNRS 6226, Avenue du Général Leclerc, 35042 Rennes, France Background: The viral broad spectrum chemokine vCCL2/vMIP-II binds to CXCR4 and CXCR7 and protects host cells against HIV-1 infection. Peptide derived from vCCL2 N-terminus (vCCL2 1-21 ) displays modest CXCR4 binding affinity and antiviral properties compared to the parental chemokine but mutations within its CC motif have been shown to enhance its antiviral properties. In this study, we selected new vCCL2 derived peptides by means of phage display and further optimized them by rational design Methods: A vCCL2 1-21 phage library in which cysteine at positions 11 and 12 (C 11 C 12 ) (Mimokine) were fully randomized was first engineered and screened against CXCR4- proteoliposomes. The most potent selected Mimokines were then further optimized by D-amino acid replacement and dimerization. Finally, a set of L- and D-bivalent ligands were evaluated for their CXCR4/CXCR7 binding and antiviral properties Results: Selection of vCCL2 1-21 library on CXCR4 resulted in the isolation of 4 Mimokines bearing FR, SR, VR and WL residues at positions C 11 and C 12 . These Mimokines fully protected MT-4 cells against infection by a HIV-1 X4 virus (HXB2) (IC 50 = 60 to 185 m M) and exhibited 3 to 4-fold higher affinity for CXCR4 (IC 50 = 480 to 740 nM) than the reference Mimokine SS (IC 50 = 2164 nM). Molecular modelling and docking into CXCR4 3D structure suggested that the enhanced affinity of Mimokines FR, SR and VR for CXCR4 might be due to the formation of an additional salt bridge between the Mimokine Arg12 and the receptor sulfated Tyr21. The potency of the selected Mimokines was further enhanced by combining dimerization and D-amino acid substitution. Bivalent Mimokines SR, VR, FR and WL in D format exhibited 10 to 20-fold increase in CXCR4 binding affinity (IC 50 = 29 to 44 nM) and 20 to 100-fold increase in antiviral activities (IC 50 = 1,8 to 6.3 m M) when compared to their respective monomeric L-counterparts. Interestingly, these bivalent D-Mimokines displayed a 100-fold reduction in binding CXCR7 (IC 50 = 5630 nM) when compared to the bivalent L-Mimokines, demonstrating that D-amino acid replacement improved both affinity and selectivity for CXCR4

Conclusions: Optimized bivalent D-Mimokines displayed 10 to 20-fold enhanced CXCR4 affinity and 20 to 100-fold improved antiviral properties when compared to the initial monomeric L-Mimokines. These bivalent D-Mimokines showed a reduced affinity for CXCR7 and may therefore serve as lead compounds for the further development of more selective CXCR4 HIV-1 inhibitors 214 HIV-1 Infection of Female Primary Genital Epithelial Cells After PseudotypingWith HTLV-1: Potential Driver of Sexual Transmission of HIV-1 Yuyang Tang 1 ; Alvin George 1 ; Oksana Petrechko 1 ; Brian Imbiakha 1 ; Stephanie Sweet 1 ;YuetsuTanaka 2 ; Franklin Nouvet 1 ; James E. Hildreth 1 1 University of California Davis, Davis, CA, US; 2 University of the Ryukyus, Nishihara-cho, Japan Background: Young females are at high risk of HIV infection and constitute 75% of infected individuals in some sub-Saharan Africa countries. Some regions with high prevalence of HIV-1 are often also highly endemic for HTLV. HIV/HTLV co-infection in Africa, Latin America and the Caribbean basin is increasing and has emerged as a global health problem. In our recently published study we demonstrated that HIV-1 is able to acquire envelope glycoproteins of a gammaretrovirus during co-infection, in a process we called “natural pseudotyping”, and expand its cellular tropism enabling it to infect primary female genital epithelial cells. Natural pseudotyping may dramatically increase risk of female HIV-1 infection during sexual intercourse and therefore could be a biological factor contributing to the devastating spread of HIV in young females in Africa and other regions of the world. Methods: T cells were coinfected with both HIV-1 and HTLV-1. The progeny virus was exposed to primary vaginal and cervical epithelial cells. HIV-1 and HTLV-1 infection was measured by immunofluorescence staining with antibody anti-HIV-1 Gag antibody or anti-HTLV-1 Gag, the viral release from epithelial cells was measured by ELISA and qRT-PCR. Results: Progeny virus from HTLV-1/HIV-1 co-infected T cells was capable of infecting primary vaginal and cervical epithelial cells via both cell-associated and free virus mediated infection. No HIV-1 infection was observed from epithelial cells exposed to progeny virus from T cells infected with HIV-1 alone. Infection of primary genital cells was significantly reduced by antisera against the HTLV-1 glycoprotein, indicating that HIV-1 infection was mediated by the HTLV glycoprotein. Active HIV-1 replication infection in primary genital epithelial cells was confirmed by inhibition with protease inhibitors. However, HIV-1 reverse transcriptase inhibitors AZT or Rilpivirine only partially blocked HIV-1 infection in primary genital epithelial cells. Further analysis indicated that AZT or Rilpivirine treatment blocked HIV-1 infection in cells infected with HIV-1 alone but not in cells infected by both HIV-1 and HTLV-1. Since AZT and Rilpivirine have very limited effects on HTLV-1 replication we conclude that HTLV-1 RT conferred resistance by HIV-1 to HIV-1 RT inhibitors.

Poster Abstracts

207

CROI 2015