Infection of rhesus macaques with a pool of simian immunodeficiency virus with the envelope genes from acute HIV-1 infections.

Kendall C Krebs,Eric J Arts,Mohammed Asmal,Kenneth Nelson,Robin J Shattock,Ronald S Veazey,Richard Gibson,Yong Gao,Meijuan Tian,Binhua Ling,Kenneth Henry,Norman Letvin,Yuejin Li,Weining Han

doi:10.1186/s12981-016-0125-8

Abstract

BackgroundNew simian–human immunodeficiency chimeric viruses with an HIV-1 env (SHIVenv) are critical for studies on HIV pathogenesis, vaccine development, and microbicide testing. Macaques are typically exposed to single CCR5-using SHIVenv which in most instances does not reflect the conditions during acute/early HIV infection (AHI) in humans. Instead of individual and serial testing new SHIV constructs, a pool of SHIVenv_B derived from 16 acute HIV-1 infections were constructed using a novel yeast-based SHIV cloning approach and then used to infect macaques.ResultsEven though none of the 16 SHIVenvs contained the recently reported mutations in env genes that could significantly enhance their binding affinity to RhCD4, one SHIVenv (i.e. SHIVenv_B3-PRB926) established infection in macaques exposed to this pool. AHI SHIVenv_B viruses as well as their HIVenv_B counterparts were analyzed for viral protein content, function, and fitness to identify possible difference between SHIVenv_B3-PRB926 and the other 15 SHIVenvs in the pool. All of the constructs produced SHIV or HIV chimeric with wild type levels of capsid (p27 and p24) content, reverse transcriptase (RT) activity, and expressed envelope glycoproteins that could bind to cell receptors CD4/CCR5 and mediate virus entry. HIV-1env_B chimeric viruses were propagated in susceptible cell lines but the 16 SHIVenv_B variants showed only limited replication in macaque peripheral blood mononuclear cells (PBMCs) and 174×CEM.CCR5 cell line. AHI chimeric viruses including HIVenv_B3 showed only minor variations in cell entry efficiency and kinetics as well as replicative fitness in human PBMCs. Reduced number of N-link glycosylation sites and slightly greater CCR5 affinity/avidity was the only distinguishing feature of env_B3 versus other AHI env’s in the pool, a feature also observed in the HIV establishing new infections in humans.ConclusionDespite the inability to propagate in primary cells and cell lines, a pool of 16 SHIVenv viruses could establish infection but only one virus, SHIVenv_B3 was isolated in the macaque and then shown to repeatedly infected macaques. This SHIVenv_B3 virus did not show any distinct phenotypic property from the other 15 SHIVenv viruses but did have the fewest N-linked glycosylation sites.Electronic supplementary materialThe online version of this article (doi:10.1186/s12981-016-0125-8) contains supplementary material, which is available to authorized users.

Highlights

New simian–human immunodeficiency chimeric viruses with an Human immunodeficiency virus type 1 (HIV-1) env (SHIVenv) are critical for studies on HIV pathogenesis, vaccine development, and microbicide testing
We utilized the env gene from 20 acute HIV-1 infections to construct over 70 SHIVenv viruses using our yeast based cloning system
Based on reiterative cloning of various cassettes, we discovered that the selective introduction of a gp120 coding region into a SHIVenv_KB9 construct resulted in virus production with a functional Env

Summary

Introduction

New simian–human immunodeficiency chimeric viruses with an HIV-1 env (SHIVenv) are critical for studies on HIV pathogenesis, vaccine development, and microbicide testing. While chimpanzees can be productively infected, they are endangered, expensive, do not typically develop AIDS after HIV-1 infection, and their use in research engenders ethical concerns [1] This narrow host range of HIV-1 has compelled researchers to use macaque monkeys exposed or infected with SHIVenv, a chimera containing HIV-1 env coding regions within a simian immunodeficiency virus (SIV) backbone derived from rhesus macaques (Macaca mulatta) infections. The genomic organization of SIVmac, HIV-1, and SHIV constructs are similar but encode for virus with significant functional variations These differences are largely based on the accessory proteins, which appear to modulate viral replication in a host species-dependent manner impacting virus persistence, spread, and pathogenesis [2,3,4,5]. A recent study showed that the HIV harboring the SIVmac vif gene could establish infection and was pathogenic in pigtailed macaques (Macaca nemestrina) depleted for CD8+ T cells [6]

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