Expression of Immunodominant gI Protein of Duck Enteritis Virus and its Evaluation for ELISA

Background: Duck plague (DP), also known as duck viral enteritis (DVE) caused by Anatid alpha herpesvirus-1, is the major infectious viral disease reported in India very often with significant economic losses due to high morbidity and mortality. The genome is approximately 158,091 bp with a genomic arrangement pattern (UL-IRS-US-TRS) that corresponds to type-D herpesvirus. The incubation period of the disease in domestic ducks ranges from 3 to 7 days and the mortality varies from 5-100%. It has been reported that the strategies to monitor and control DVE were often frustrating because the disease tends to establish a latent infection in waterfowl and vaccination failure. The present study was taken as an attempt to develop indirect ELISA using developed recombinant gI protein to diagnose DEV in field condition. Methods: In this study, we selected a membrane glycoprotein protein I (US7) gene, that plays an important role in virion sorting, cell-cell spread and binding of IgG Fc receptor. The gI protein was cloned with pET-32a (+) and expressed in a prokaryotic (E. coli) expression system. Further, recombinant protein was purified by nickel column affinity chromatography and refolded by dialysis. The obtained concentrated protein was then evaluated for its antigenicity and reliability in an Indirect-Enzyme-linked immunosorbent assay (ELISA) for DEV antibody detection in duck sera. Result: A panel of positive, negative and vaccinal serum was evaluated which indicated the potential use of the protein in the development of a serological assay for sero- surveillance of duck plague infection.