Co-infection of S1 mutants of 4/91-like Infectious Bronchitis Virus with Mycoplasma gallisepticum in backyard poultry flock with a respiratory problem

This study aimed to detect possible viral agents in backyard poultry where numerous commercial poultry companies are located. The backyard flock had non-vaccinated 30 meat-type chickens and four turkey pullets. Serum samples and tracheal swabs were taken from chickens and turkey pullets showing respiratory signs. Serum antibody levels were measured using commercial ELISA kits against Avian Influenza Virus (AIV), Newcastle Disease Virus (NDV), Infectious Bronchitis Virus (IBV), Avian Metapneumovirus (AMPV), Mycoplasma gallisepticum (MG), Mycoplasma synoviae (MS), and Ornithobacterium rhinotracheale (ORT). In addition, tracheal swabs were tested for AIV serotypes H5, H7, and H9, NDV, IBV, AMPV, MG, MS, Pasteurella multocida, Avibacterium paragallinarum, and Bordetella avium by circular amplification technology (CAT). Anti-MS, -IBV, -MG, -NDV, -AMPV, and -ORT IgG antibodies were detected in some chicken sera, while anti-NDV, -MG, -MS, and -ORT IgG antibodies were detected in turkey sera. All avian tracheal swabs were positive for MG; however, IBV was only detected from chicken tracheal samples by CAT. The IBV strains were genotyped by sequencing a part of the S1 glycoprotein gene. Two isolates showed 99.35% and 98.69% nucleotide and 99.02% amino acid similarities with the 4/91 IBV strain. Two strains showed 99.35% nucleotide and 100% amino acid sequence identity to each other. Turkeys and chickens in the flock had MG and MG/IBV co-infections, respectively. Consequently, the presence of mutants of 4/91 IBV genotypes and MG found in backyard poultry could be a potential epidemiological source for commercial flocks in poultry integrations.