Related Experiment Video
Updated: Mar 20, 2026
Analysis of Simian Immunodeficiency Virus-specific CD8+ T-cells in Rhesus Macaques by Peptide-MHC-I Tetramer Staining
Published on: December 23, 2016
Envelope residue 375 substitutions in simian-human immunodeficiency viruses enhance CD4 binding and replication in
Hui Li1, Shuyi Wang1, Rui Kong1
1Department of Medicine, University of Pennsylvania, Philadelphia, PA 19104;
Abstract:
Most simian-human immunodeficiency viruses (SHIVs) bearing envelope (Env) glycoproteins from primary HIV-1 strains fail to infect rhesus macaques (RMs). We hypothesized that inefficient Env binding to rhesus CD4 (rhCD4) limits virus entry and replication and could be enhanced by substituting naturally occurring simian immunodeficiency virus Env residues at position 375, which resides at a critical location in the CD4-binding pocket and is under strong positive evolutionary pressure across the broad spectrum of primate lentiviruses. SHIVs containing primary or transmitted/founder HIV-1 subtype A, B, C, or D Envs with genotypic variants at residue 375 were constructed and analyzed in vitro and in vivo. Bulky hydrophobic or basic amino acids substituted for serine-375 enhanced Env affinity for rhCD4, virus entry into cells bearing rhCD4, and virus replication in primary rhCD4 T cells without appreciably affecting antigenicity or antibody-mediated neutralization sensitivity. Twenty-four RMs inoculated with subtype A, B, C, or D SHIVs all became productively infected with different Env375 variants-S, M, Y, H, W, or F-that were differentially selected in different Env backbones. Notably, SHIVs replicated persistently at titers comparable to HIV-1 in humans and elicited autologous neutralizing antibody responses typical of HIV-1. Seven animals succumbed to AIDS. These findings identify Env-rhCD4 binding as a critical determinant for productive SHIV infection in RMs and validate a novel and generalizable strategy for constructing SHIVs with Env glycoproteins of interest, including those that in humans elicit broadly neutralizing antibodies or bind particular Ig germ-line B-cell receptors.
Insights
Modifying simian-human immunodeficiency virus (SHIV) envelope proteins enhances binding to rhesus macaque CD4 cells, enabling efficient infection and AIDS development in macaques. This strategy aids in creating better SHIV models for HIV-1 research.
Area of Science:
- Virology
- Immunology
- Primate Models
Background:
- Most simian-human immunodeficiency viruses (SHIVs) with primary HIV-1 envelope (Env) glycoproteins do not infect rhesus macaques (RMs).
- Inefficient Env binding to rhesus CD4 (rhCD4) is a potential barrier to SHIV entry and replication in RMs.
- Amino acid residue 375 in Env is critical for CD4 binding and shows evolutionary pressure in primate lentiviruses.
Purpose of the Study:
- To investigate if enhancing Env binding to rhCD4 can improve SHIV infectivity in RMs.
- To develop a generalizable strategy for constructing SHIVs with specific Env glycoproteins for research.
Main Methods:
- Constructed SHIVs with primary HIV-1 subtype A, B, C, or D Envs featuring variants at residue 375.
- Analyzed Env binding affinity to rhCD4, virus entry into rhCD4+ cells, and replication in primary rhCD4+ T cells in vitro.
- Inoculated 24 RMs with various Env375 variant SHIVs and monitored infection, viral loads, antibody responses, and disease progression.
Main Results:
- Substitutions at Env residue 375 with bulky hydrophobic or basic amino acids enhanced Env affinity for rhCD4, virus entry, and replication in rhCD4+ cells.
- All 24 RMs inoculated with subtype A, B, C, or D SHIVs became productively infected, with Env375 variants selected based on Env backbone.
- SHIVs replicated persistently in RMs, similar to HIV-1 in humans, and induced typical autologous neutralizing antibody responses; seven animals developed AIDS.
Conclusions:
- Env-rhCD4 binding is a critical determinant for productive SHIV infection in RMs.
- The strategy of modifying Env residue 375 is a novel and generalizable method for creating SHIVs with desired Env glycoproteins.
- This approach facilitates the study of SHIVs expressing Envs that elicit broadly neutralizing antibodies or bind specific B-cell receptors in humans.
More Related Videos
07:10Conformational Evaluation of HIV-1 Trimeric Envelope Glycoproteins Using a Cell-based ELISA Assay
Published on: September 14, 2014
13:13Single-cell Quantitation of mRNA and Surface Protein Expression in Simian Immunodeficiency Virus-infected CD4+ T Cells Isolated from Rhesus macaques
Published on: September 25, 2018