Expression of chicken circovirus Cap protein and establishment of ELISA method for antibody detection

A recently identified virus, chicken circovirus (ChCV), has been linked to the onset of acute gastroenteritis in chicks, a condition that can have a detrimental impact on the overall health and well-being of chickens in a farming setting. In this study, we developed an enzyme-linked immunosorbent assay (ELISA) method for the indirect detection of antibodies against the chicken circovirus (ChCV) through codon optimization, which effectively expressed the capsid protein of the ChCV and utilized it as an encapsulated antigen following purification. In establishing the ELISA method for detecting antibodies using the purified Cap protein as the antigen, the optimal concentration of the antigen was determined to be 1 µg/mL, the optimal blocking solution was identified as 1% bovine serum albumin, the optimal dilution ratio of the serum to be tested was established to be 1:100, and the dilution ratio of the secondary antibody was determined to be 1:5,000. At these thresholds, the sensitivity of the ELISA method was 94.44%, and the specificity was 100%. The testing of 203 clinical samples yielded a positivity rate of 46.8%, indicating that the virus is endemic in chickens. In conclusion, this study established an ELISA method to detect antibodies against chicken circovirus using recombinant Cap protein as antigen, demonstrating good specificity and sensitivity. This lays the foundation for the development of related kits and the detection of infection and epidemiology of chicken circovirus. Meanwhile, the analysis concluded that chicken circovirus infection is more common, and the prevention and control of this disease should be emphasised and strengthened.