Standardization And Evaluation Of An In-House ELISA For The Detection Of Rabies Antibody In A Tertiary Care Centre In South India

Abstract

BackgroundRapid fluorescent focus inhibition test (RFFIT), a neutralization-based assay for detecting rabies antibodies, is the gold standard. The National Action Plan for Dog Mediated Rabies Elimination (NAPRE) is a national program that strategizes the establishment of enzyme-linked immunosorbent assays (ELISA) to detect rabies antibodies. ObjectiveWe developed an in-house ELISA to screen for rabies antibodies using rabies vaccine antigen to study vaccine response among health care workers (HCWs) who received pre-exposure prophylaxis and a few animal bite victims who received post-exposure prophylaxis with rabies vaccine. Study designA prospective study was carried out from April to September 2023 at the Department of Clinical Virology of a tertiary care center in South India. A total of 161 serum specimens, which included 155 serum samples from study participants and 6 samples from a reference laboratory (as controls), were obtained during the study period. Rabies antibody was determined by the in-house standardized ELISA developed using the rabies vaccine and compared with the reference assay, RFFIT. The accuracy indices of the in-house ELISA were estimated by MedCalc software (version 22.023). ResultsA panel of 86 positive and 75 negative serum samples was used for evaluating the in-house standardized ELISA. The sensitivity, specificity, positive and negative predictive values of the in-house ELISA were 98.8%, 100%, 100%, and 98.7% respectively. The accuracy of the in-house ELISA is 99.4%. ConclusionELISA can be a practically feasible and less expensive assay compared to RFFIT which is a cumbersome procedure with a long turn-around time of 3-4 days.