R5 clade C SHIV strains with tier 1 or 2 neutralization sensitivity: tools to dissect env evolution and to develop AIDS vaccines in primate models.


BACKGROUND: HIV-1 clade C (HIV-C) predominates worldwide, and anti-HIV-C vaccines are urgently needed. Neutralizing antibody (nAb) responses are considered important but have proved difficult to elicit. Although some current immunogens elicit antibodies that neutralize highly neutralization-sensitive (tier 1) HIV strains, most circulating HIVs exhibiting a less sensitive (tier 2) phenotype are not neutralized. Thus, both tier 1 and 2 viruses are needed for vaccine discovery in nonhuman primate models. METHODOLOGY/PRINCIPAL FINDINGS: We constructed a tier 1 simian-human immunodeficiency virus, SHIV-1157ipEL, by inserting an "early," recently transmitted HIV-C env into the SHIV-1157ipd3N4 backbone [1] encoding a "late" form of the same env, which had evolved in a SHIV-infected rhesus monkey (RM) with AIDS. SHIV-1157ipEL was rapidly passaged to yield SHIV-1157ipEL-p, which remained exclusively R5-tropic and had a tier 1 phenotype, in contrast to "late" SHIV-1157ipd3N4 (tier 2). After 5 weekly low-dose intrarectal exposures, SHIV-1157ipEL-p systemically infected 16 out of 17 RM with high peak viral RNA loads and depleted gut CD4+ T cells. SHIV-1157ipEL-p and SHIV-1157ipd3N4 env genes diverge mostly in V1/V2. Molecular modeling revealed a possible mechanism for the increased neutralization resistance of SHIV-1157ipd3N4 Env: V2 loops hindering access to the CD4 binding site, shown experimentally with nAb b12. Similar mutations have been linked to decreased neutralization sensitivity in HIV-C strains isolated from humans over time, indicating parallel HIV-C Env evolution in humans and RM. CONCLUSIONS/SIGNIFICANCE: SHIV-1157ipEL-p, the first tier 1 R5 clade C SHIV, and SHIV-1157ipd3N4, its tier 2 counterpart, represent biologically relevant tools for anti-HIV-C vaccine development in primates.





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Publication Info

Siddappa, Nagadenahalli B, Jennifer D Watkins, Klemens J Wassermann, Ruijiang Song, Wendy Wang, Victor G Kramer, Samir Lakhashe, Michael Santosuosso, et al. (2010). R5 clade C SHIV strains with tier 1 or 2 neutralization sensitivity: tools to dissect env evolution and to develop AIDS vaccines in primate models. PLoS One, 5(7). p. e11689. 10.1371/journal.pone.0011689 Retrieved from https://hdl.handle.net/10161/4555.

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David Charles Montefiori

Professor in Surgery

Dr. Montefiori is Professor and Director of the Laboratory for HIV and COVID-19 Vaccine Research & Development in the Department of Surgery, Division of Surgical Sciences at Duke University Medical Center. His major research interests are viral immunology and HIV and COVID-19 vaccine development, with a special emphasis on neutralizing antibodies.

Multiple aspects of HIV-1 neutralizing antibodies are studied in his laboratory, including mechanisms of neutralization and escape, epitope diversity among the different genetic subtypes and geographic distributions of the virus, neutralizing epitopes, requirements to elicit protective neutralizing antibodies by vaccination, optimal combinations of neutralizing antibodies for immunoprophylaxis, and novel vaccine designs for HIV-1. Dr. Montefiori also directs large vaccine immune monitoring programs funded by the NIH and the Bill & Melinda Gates Foundation that operate in compliance with Good Clinical Laboratory Practices and has served as a national and international resource for standardized assessments of neutralizing antibody responses in preclinical and clinical trials of candidate HIV vaccines since 1988.

At the onset of the COVID-19 pandemic he turned his attention to SARS-CoV-2, with a special interest in emerging variants and how they might impact transmission, vaccines and immunotherapeutics. His rapid response to emerging SARS-CoV-2 variants of concern provided some of the earliest evidence of the potential risk the variants pose to vaccines. In May 2020, his laboratory was recruited by the US Government to lead the national neutralizing antibody laboratory program for COVID-19 vaccines.

His laboratory utilizes FDA approved validated assay criteria to facilitate regulatory approvals of COVID-19 vaccines. He has published over 750 original research papers that have helped shape the scientific rationale for antibody-based vaccines.

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