A MONOCLONAL ANTIBODY-BASED ANTIGEN CAPTURE ENZYME-LINKED-IMMUNOSORBENT-ASSAY FOR IDENTIFICATION OF INFECTIOUS-BRONCHITIS VIRUS SEROTYPES

An antigen-capture enzyme-linked immunosorbent assay (C-ELISA) was dev eloped for detection and identification of infectious bronchitis virus (IBV) serotypes Arkansas, Connecticut, and Massachusetts using monocl onal antibodies (MAbs) specific to the S1 glycoprotein of the respecti ve serotype. The assay (designed as a double-antibody sandwich assay) gave the best results when the S1-specific MAb, antigen, and chicken s erum were of the same serotype. However, when a group-specific (M glyc oprotein-specific) MAb was used for antigen capture, a distinctive pat tern of cross-reactivity was observed between the antigens and heterol ogous chicken sera, suggesting a complex distribution of epitopes on t he IBV M glycoproteins. Treatment of antigen with NP40 enhanced the EL ISA signal only when the M glycoprotein-specific MAb was used for anti gen capture. Although C-ELISA was inconsistent in detecting IBV in chi cken tissue homogenates, it was highly effective in detecting the viru s in allantoic fluid after the homogenates were given one chicken embr yo passage.