Viral antibody screening system that uses a standardized single dilution immunoglobulin G enzyme immunoassay with multiple antigens

Abstract

An enzyme-linked immunosorbent assay (ELISA) system for the simultaneous determination of IgG antibodies in human sera directed against several viruses is presented. Antibodies to up to 8 different viruses could be determined for 3 different sera on 1 microtitration plate. After subtraction of the absorbance values obtained with the control antigens, the viral antigen absorbancies were expressed as percentages of the absorbance obtained with a pooled Ig standard. This value, the relative antibody activity, was rapidly calculated by means of a computer directly connected to the ELISA photometer and was stored on magnetic discs, thereby facilitating seroepidemiological studies. The reproducibility of the relative antibody activity was calculated to at best .+-. 3.6% (SD) in an intraassay test and to at worst .+-. 20.4% (SD) in an interassay test. Each serum was analyzed only at a dilution of 1/75. The sensitivity of this single-dilution ELISA (SD-ELISA) method for the detection of titer rises was compared with those of conventional methods, mostly complement fixation but also hemagglutination inhibition. Of 155 paired sera showing 4-fold complement fixation or hemagglutination inhibition rises, 142 (92%) also showed significant results in SD-ELISA. Of 57 significant relative antibody activity rises, 22 (39%) were significant in complement fixation or hemagglutination inhibition. Overall, up to twice as many significant titer rises were detected with SD-ELISA. Most of these seemed to have a sound to correlation with clinical data. The specificity of SD-ELISA was similar to that of complement fixation, with some cross-reactions occurring between herpes simplex and varicella-zoster virus antigens and between parainfluenza viruses. Apparently, SD-ELISA is a valuable clinical virological tool that supplements conventional serology.