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

Abstract

We present an enzyme-linked immunosorbent assay (ELISA) system for the simultaneous determination of immunoglobulin G antibodies directed against several viruses. Antibodies to up to eight different viruses could be determined for three different sera on one 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 immunoglobulin 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 disks, thereby facilitating seroepidemiological studies. The reproducibility of the relative antibody activity was calculated to at best +/- 3.6% (standard deviation) in an intraassay test and to at worst +/- 20.4% (standard deviation) 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. A total of 142 of 155 (92%) paired sera showing fourfold complement fixation or hemagglutination inhibition rises also showed significant results in SD-ELISA. A total of 22 of 57 (39%) significant relative antibody activity rises were significant in complement fixation or hemagglutination inhibition. Overall, up to twice as many significant titer rises could be detected with SD-ELISA. Most of these seemed to have a sound correlation with clinical data. The specificity of SD-ELISA was found to be similar to that of complement fixation, with some cross-reactions occurring between herpes simplex and varicella-zoster virus antigens and between parainfluenza viruses. We have found SD-ELISA to be a valuable clinical virological tool that supplements conventional serology.