Method for detection of simian immunodeficiency virus neutralizing antibodies using a noncommercial antigen capture enzyme-linked immunosorbent assay

SIV- and HIV-2-neutralising antibodies in infected macaques measured by a novel and simple neutralisation test based on a non-commercial antigen-ELISA

A method for the measurement of neutralising antibodies (nab) directed against SIVmac or HIV-2 was developed. The assay is based on antigen detection using a non-commercial enzyme-linked immunosorbent assay (ELISA). Studies were carried out to determine the influence of the test conditions on the nab titre. The sensitivity of the assay depended mainly on the virus dose and the length of incubation of the serum-virus-mixture. Prolongation of the culture time from 9 to 11 days increased the validity of the results. Applying this neutralisation assay on sequential serum samples from SIV mac- or HIV-2ben-infected macaques, a considerable variation was found in nab titres between individual animals. Whereas after infection with SIVmac, in vitro-neutralisation seems to correlate with protection against disease, and the lower pathogenity of HIV-2ben in macaques compared with SIVmac is not due to the differences in nab titres.

International collaboration comparing neutralization and binding assays for monoclonal antibodies to simian immunodeficiency virus

Thirteen laboratories characterized a coded panel of 10 MAbs to SIVmac251 envelope protein in a collaboration organized by the National Institute of Allergy and Infectious Diseases (NIAID). The MAbs were examined against SIV isolates in neutralization and radioimmune precipitation, immunoblot, enzyme-linked immunosorbent, and radioimmune assays. Although laboratories employed diverse neutralization assays that varied in sensitivity there was agreement on the relative ability of the MAbs to neutralize SIVmac251. Additionally, even though the quantity of any single MAb required to neutralize SIVmac251 varied between laboratories, there was agreement on the rank-order strength fo the five neutralizing MAbs. Based on the data from this study, the MAbs were classified according to their neutralization potential as high efficiency (MAb concentration, < 5 micrograms/ml), low efficiency (MAb concentration, 5-100 micrograms/ml), or nonneutralizing (MAb concentration, > 100 micrograms/ml). The MAbs could be assigned to four serological groups based on ability to cross-neutralize and bind different SIV isolates. The distinction between groups I, II, and III were based on the limited neutralization data obtained with the sooty mangabey isolate.