A comparison of labelled antibody methods for the detection of virus antigens in cell monolayers

A number of labelled antibody methods have been applied to the detection of Semliki Forest virus antigens after replication of the virus in monolayers of host cells in multi-wellpolystyrene plates. The importance of several reaction variables has been investigated and the sensitivity of the methods compared for different periods of virus replication. Direct assays with radio-labelled antibody (RLA) and indirect assays using peroxidase-antiperoxidase complexes (PAP) were equally sensitive. Direct and indirect assays using enzyme-linked antibodies (ELA) were slightly less sensitive than direct RLA and PAP methods but were more sensitive than the indirect RLA or fluorescent antibody (FLA) methods. Direct assays using ELA were more rapid and easier to perform than the other assay methods.