A rapid solution immunoassay to quantify binding of the human immunodeficiency virus envelope glycoprotein to soluble...

Area of Science:

• Biochemistry
• Immunology
• Virology

Background:

• The interaction between human immunodeficiency virus (HIV) external glycoprotein (gp120) and soluble CD4 (sCD4) is crucial for understanding viral entry.
• Quantifying this binding in solution is essential for developing effective HIV therapeutics and diagnostics.

Purpose of the Study:

• To develop a rapid, quantitative assay for measuring gp120-sCD4 binding in solution.
• To assess the suitability of recombinant gp120 and various sCD4 preparations for this assay.

Main Methods:

• Development of a particle concentration fluorescent immunoassay.
• Quantification of gp120 binding to sCD4 using the developed assay.
• Evaluation of gp120 purified from recombinant baculovirus-infected insect cells.
• Assessment of sCD4 from recombinant E. coli and mammalian cells.

Main Results:

• The developed immunoassay is rapid (1 hour) and quantitative.
• The assay requires as little as 0.1 pmole of gp120 per evaluation.
• Recombinant gp120 is suitable for the assay.
• sCD4 variants (two N-terminal domains, some linked to Pseudomonas exotoxin A) bind gp120 similarly, regardless of their source (E. coli or mammalian cells).

Conclusions:

• A novel, sensitive fluorescent immunoassay has been established for quantifying gp120-sCD4 interactions.
• The assay's efficiency and sensitivity facilitate further research into HIV-host cell interactions.
• The findings support the use of various recombinant sCD4 preparations in binding studies, simplifying experimental design.