Recombinant protein-based ELISA for detection and differentiation of antibodies against avian reovirus in vaccinated and non-vaccinated chickens

Two nonstructural genes, σNS and P17, of avian reovirus (ARV) were cloned into the expression plasmid vector PGEX4T-1. Expressed proteins for σNS and P17 of avian reovirus were purified and used as antigens. Three indirect σNS enzyme-linked immunosorbent assays (ELISAs), σNS-ELISA, P17-ELISA and σNS-P17-ELISA were optimized and used as specific tests. Serum samples from reovirus-infected and vaccinated SPF chickens were tested with the three ELISAs and an agar gel precipitin (AGP) method. ELISAs specific for σNS, P17 and σNS-P17 were able to detect specific antibodies for avian reovirus in 88.9%, 61.1%, and 88.9% in infected samples, respectively, whereas the AGP detected 55.6% of the infected samples. The detection rates of ELISA specific antibodies for σNS, P17 and σNS-P17 on sera of vaccinated chickens were 6.7%, 0% and 6.7%. However, in comparison the AGP method detected 60.6% of antibodies in serum samples from vaccinated chickens. The results showed that the use of ELISAs specific for the nonstructural proteins might be able to distinguish between reovirus vaccinated and infected chickens. Further studies are in progress to validate these recombinant protein-based ELISAs under field conditions.