title: Distinct HIV-1 entry phenotypes are associated with transmission, subtype specificity, and resistance to broadly neutralizing antibodies.
abstract: BACKGROUND
  The efficiency of CD4/CCR5 mediated HIV-1 entry has important implications for pathogenesis and transmission. The HIV-1 receptor affinity profiling (Affinofile) system analyzes and quantifies the infectivity of HIV-1 envelopes (Envs) across a spectrum of CD4/CCR5 expression levels and distills these data into a set of Affinofile metrics. The Affinofile system has shed light on how differential CD4/CCR5 usage efficiencies contributes to an array of Env phenotypes associated with cellular tropism, viral pathogenesis, and CCR5 inhibitor resistance. To facilitate more rapid, convenient, and robust analysis of HIV-1 entry phenotypes, we engineered a reporter Affinofile system containing a Tat- and Rev-dependent Gaussia luciferase-eGFP-Reporter (GGR) that is compatible with the use of pseudotyped or replication competent viruses with or without a virally encoded reporter gene. This GGR Affinofile system enabled a higher throughput characterization of CD4/CCR5 usage efficiencies associated with differential Env phenotypes.
  
  
  RESULTS
  We first validated our GGR Affinofile system on isogenic JR-CSF Env mutants that differ in their affinity for CD4 and/or CCR5. We established that their GGR Affinofile metrics reflected their differential entry phenotypes on primary PBMCs and CD4+ T-cell subsets. We then applied GGR Affinofile profiling to reveal distinct entry phenotypes associated with transmission, subtype specificity, and resistance to broadly neutralizing antibodies (BNAbs). First, we profiled a panel of reference subtype B transmitted/founder (T/F) and chronic Envs (n = 12) by analyzing the infectivity of each Env across 25 distinct combinations of CD4/CCR5 expression levels. Affinofile metrics revealed that at low CCR5 levels, our panel of subtype B T/F Envs was more dependent on high levels of CD4 for HIV-1 entry compared to chronic Envs. Next, we analyzed a reference panel of 28 acute/early subtype A-D Envs, and noted that subtype C Envs could be distinguished from the other subtypes based on their infectivity profiles and relevant Affinofile metrics. Lastly, mutations known to confer resistance to VRC01 or PG6/PG19 BNAbs, when engineered into subtypes A-D Envs, resulted in significantly decreased CD4/CCR5 usage efficiency.
  
  
  CONCLUSIONS
  GGR Affinofile profiling reveals pathophysiological phenotypes associated with varying HIV-1 entry efficiencies, and highlight the fitness costs associated with resistance to some broadly neutralizing antibodies.
authors: Kelechi
authors: K
authors: Chikere
authors: Nicholas E
authors: NE
authors: Webb
authors: Tom
authors: T
authors: Chou
authors: Katharina
authors: K
authors: Borm
authors: Jasminka
authors: J
authors: Sterjovski
authors: Paul R
authors: PR
authors: Gorry
authors: Department of Microbiology, Immunology, and Molecular Genetics, Los Angeles, USA. benhur.lee@mssm.edu.
authors: Benhur
authors: B
authors: Lee
mesh_terms: D057134:Antibodies, Neutralizing / Q000627:therapeutic use*; D015704:CD4 Antigens / Q000502:physiology; D015483:HIV Antibodies / Q000627:therapeutic use*; D015658:HIV Infections / Q000635:transmission*; D015497:HIV-1 / Q000145:classification / Q000502:physiology*; D006801:Humans; D009154:Mutation; D010641:Phenotype; D019713:Receptors, CCR5 / Q000502:physiology; D016176:T-Lymphocyte Subsets / Q000821:virology; D014759:Viral Envelope Proteins / Q000502:physiology; D053586:Virus Internalization
chemical_list: D057134:Antibodies, Neutralizing; C584933:CCR5 protein, human; D015704:CD4 Antigens; D015483:HIV Antibodies; D019713:Receptors, CCR5; D014759:Viral Envelope Proteins