Single-round HIV type 1 neutralization measured by ELISPOT technique in primary human cells

Area of Science:

• Immunology
• Virology
• Assay Development

Background:

• Accurate quantification of HIV-1 neutralizing antibody titers is crucial for vaccine development and therapeutic strategies.
• Existing methods for measuring neutralization may have limitations in sensitivity or applicability to primary cells.

Purpose of the Study:

• To develop and validate a novel, single-round focus-forming unit (FFU) reduction assay for quantifying HIV-1 neutralizing antibody titers.
• To compare the performance of the new assay with a standard enzyme immunoassay (EIA) method.

Main Methods:

• Development of an ELISPOT neutralization assay (ENA) using human peripheral blood mononuclear cells (PBMC).
• Enumeration of infected PBMC via reverse ELISPOT, detecting viral p24 secretion.
• Visual counting of spots and determination of neutralization titers using curve-fitting software.

Main Results:

• The ENA accurately quantifies HIV-1 neutralizing antibody titers in primary human cells.
• The assay effectively measures FFU reduction for both syncytium-inducing (SI) and non-syncytium-inducing (NSI) primary HIV-1 isolates.
• Results from the ENA showed comparable performance to the standard PBMC neutralization assay (standard assay) using EIA.

Conclusions:

• The ELISPOT neutralization assay (ENA) provides a robust and visually countable method for assessing HIV-1 neutralizing antibody responses.
• This assay is suitable for use with primary human cells and various HIV-1 isolates.
• The ENA offers a valuable tool for HIV-1 research, potentially aiding in the evaluation of vaccine candidates and therapeutic antibodies.