Quantifying CD4/CCR5 Usage Efficiency of HIV-1 Env Using the Affinofile System.

Area of Science:

• Virology
• Cell Biology
• Immunology

Background:

• HIV-1 entry into target cells depends on interactions between the HIV envelope (Env) and cellular receptors CD4 and coreceptors (CXCR4 or CCR5).
• The efficiency of Env interaction with these receptors significantly influences cellular tropism and is linked to pathological Env phenotypes.

Purpose of the Study:

• To describe the Affinofile system, a 293-based dual-inducible cell line for expressing CD4 and CCR5 combinations.
• To present the Viral Entry Receptor Sensitivity Assay (VERSA) metrics for quantifying CD4/CCR5-dependent HIV-1 infectivity.
• To enable high-resolution profiling of HIV-1 Env usage efficiency across diverse viral phenotypes.

Main Methods:

• Utilized the Affinofile system, a cell line engineered to express up to 25 distinct combinations of CD4 and CCR5.
• Employed the Viral Entry Receptor Sensitivity Assay (VERSA) to measure viral infectivity based on CD4 and CCR5 usage.
• Analyzed the relationship between specific viral phenotypes and their efficiency in utilizing CD4 and CCR5 for cell entry.

Main Results:

• The Affinofile system allows for precise control over CD4 and CCR5 expression levels and combinations.
• VERSA metrics provide quantitative data on the infectivity of HIV-1 variants across different receptor expression profiles.
• Demonstrated the capability of the system to resolve nuanced differences in receptor usage efficiency among various HIV-1 Env phenotypes.

Conclusions:

• The Affinofile system coupled with VERSA offers a powerful tool for detailed analysis of HIV-1 entry mechanisms.
• This approach facilitates a deeper understanding of how variations in CD4 and CCR5 usage contribute to HIV-1 tropism and pathogenesis.
• High-resolution profiling of receptor usage is crucial for characterizing viral phenotypes and developing targeted interventions.