Application of a rapid microplaque assay for determination of human immunodeficiency virus neutralizing antibody titers.

To perform a human immunodeficiency virus (HIV) plaque assay in nonadherent host cells, we developed a novel technique in which HIV-infected MT-2 cells were formed into monolayers by centrifugation through molten agarose. Infection, formation of cell monolayers, and enumeration of plaques all took place in 96-well microtiter plates. When this process was preceded by 18 h of incubation of HIV with patient serum samples, neutralizing antibody titers between 1:10 and 1:5,000 could be accurately determined in patient serum samples. In addition to the determination of neutralizing antibody titers (with the use of various serum dilutions and a constant virus concentration), neutralization indices could also be determined with different virus dilutions and a single dilution of patient serum.