Seroprevalence and prevalence of Infectious Bronchitis Virus in broilers, laying hens and broiler breeders in Spain

Infectious Bronchitis Virus (IBV) is one of the most important viral diseases which causes important economic losses in poultry industry. This study aimed to assess the seroprevalence, prevalence, and variants of IBV in broilers, layers, and broiler breeders´ farms of Gallus gallus species in Eastern Spain. Thus, 29, 16, and 14 flocks of broilers, layers and broiler breeders, respectively were analyzed. To assess seroprevalence, sera samples were analyzed by ELISA. Tracheal swabs and tissue samples were tested by PCR to know the prevalence and detect specific variants. An IBV seroprevalence of 100% was detected in the 3 productive orientations. According to PCR results, a prevalence of 38% in broilers, 44% in layers and 43% in broiler breeders was obtained. The variant-specific RT-PCR analysis showed that 4/91, Massachusetts, QX, Italy-02 and D274 strains were present in commercial flocks in eastern Spain, being 4/91 the most prevalent in all the productive orientations. In layers 100% of QX prevalence, 14% of Italy 02 and 14% of D274 was detected. Regarding broilers, a prevalence of 18% of Massachusetts strain was also detected. In contrast, in broiler breeders´ farms only 4/91 strain was found. In conclusion, our findings showed the presence of IBV in eastern Spain and the changing situation of the IBV variants´ prevalence, being different according to the productive orientation. The continuous emergence of new variants emphasizes the importance of continuous IBV monitoring in order to optimize vaccination strategies.