Evaluation of enzyme-linked immunosorbent assay for titration of antibody to equine herpesvirus type 1

Abstract

Optical density (OD450) of an indirect enzyme-linked immunosorbent assay (ELISA) for detection of antibody to equine herpesvirus type 1 (EHV-1) was compared with agar gel immunodiffusion test (AGID) which is practically used for titration of antibody to the virus in clinics, complement fixation (CF) and neutralizing antibody titers. The correlation coefficient among them was 0,83, 0.67 and 0.44, respectively. The OD450 of ELISA was strongly correlated with antibody levels which were expressed by AGID as follows. The mean OD450 value ± standard deviation of-, +, ++ and +++ samples in the AGID, was 0.27± 0.12, 0.43 ± 0.22, 1.10± 0.34 and 1.38 ± 0.26, respectively. Change of OD450 in a horse experimentally inoculated with EHV1 was the same with that of precipitating antibody titrated with AGID and CF antibody. From these results, it was suggested that ELISA can be practically used in place of AGID for control of EHV-1 infection through titration of antibody to the virus in the field. The antigen for ELISA and AGID was suggested to be as VP 19, an inner component of the virus, because the major peptide of the antigen of both tests was estimated to have a molecular weight of 61,000 dallons by polyacrylamide gel electrophoresis.