Design, development, and interpretation of HIV neutralization assays

In developing therapeutic reagents for the control of HIV infection, it is necessary to screen candidate products in vitro for their ability to reduce or neutralize viral infection. Although the current literature describes numerous neutralization assays, no universally accepted standards have been adopted. In this article, we briefly review the available neutralization assays and describe in detail the methods we have selected in our laboratory for the screening and characterization of reagents with potential anti-HIV properties. After evaluating many different technical protocols and experimental procedures, we have found the syncytium inhibition and syncytial focus assays to be particularly useful and have found p24 gag antigen production to be an excellent objective measure of HIV infection under a variety of conditions. These assays proved reproducible and sensitive and are suitable for use in the majority of laboratories.