Abstract:
Avian infectious bronchitis (AIB) is one of the most important contagious, respiratory, acute diseases with a very high
economic impact, caused by the infectious bronchitis virus (IBV) one of the most widespread coronaviruses in the
world belonging to the genus Gammacoronavirus. The clinical evolution is characterised by the presence of respiratory,
reproductive and renal disorders. The aim of the study was to show the presence of IBV antibodies in vaccinated broiler
chickens and to determine the post-vaccinal origin or following infection with circulating wild strains. Ninety-six serum
samples from broiler, Ross 308, aged between 38 and 42 days, reared on five farms from five counties located in southwestern
Romania were studied. Analysis of the serum samples for antibodies was carried out by ELISA, staggered, at
the Synevovet Romania laboratory. Anti-IBV antibodies were identified in all farms studied. The absence of IBV
antibodies was observed in 12.5% of the samples examined. Anti-IBV antibodies were detected in 87.5% of the sera
studied. Very high values of antibody titters, above those indicated by the vaccine efficacy evaluation guidelines, were
recorded in 2/3 of the sera studied, suggesting a possible infection with wild strains. The results of the present study
indicate the need to extend the evaluation of IBV antibody titters for a clearer picture of the evolution of the infection,
but also molecular studies to differentiate vaccine strains from wild strains.
