Applying Flow Virometry to Study the HIV Envelope Glycoprotein and Differences Across HIV Model Systems

Area of Science:

• Virology
• Immunology
• Biochemistry

Background:

• The HIV envelope glycoprotein (Env) is crucial for viral entry and a key target for immune responses and vaccine design.
• Challenges in targeting Env include its glycosylation, variability, conformational masking, and low abundance on virions.
• Understanding Env's structure and presentation is vital for effective therapeutic and preventative strategies.

Purpose of the Study:

• To demonstrate the utility of flow virometry (FV) for high-throughput, single-virion phenotyping of the HIV Env.
• To characterize Env heterogeneity and conformational states using a comprehensive antibody panel.
• To assess the impact of virus-producing cell models on Env detection.

Main Methods:

• Staining of HIV virions with 85 monoclonal antibodies targeting various Env regions.
• Application of flow virometry for quantitative analysis of single virion Env expression.
• Comparison of Env detection on viruses produced from different cell lines (CD4+ T cells, HEK293T, primary cells).
• Assessment of Env conformational changes upon addition of soluble CD4.

Main Results:

• A wide range of antibodies successfully stained HIV Env, with V3 antibodies showing the highest signal.
• The cellular model used for virus production significantly influenced Env detection.
• Flow virometry detected heterogeneity in Env presentation on individual virions.
• FV sensitively identified conformational differences in Env upon soluble CD4 binding.

Conclusions:

• Flow virometry is a powerful tool for detailed characterization of HIV Env at the single-virion level.
• FV can reveal critical insights into Env heterogeneity and conformational dynamics, relevant for vaccine design.
• The choice of cell model impacts Env detection, highlighting the need for relevant systems in research.