Submitted to: Meeting Abstract
Publication Type: Abstract Only
Publication Acceptance Date: 3/7/2021
Publication Date: N/A
Technical Abstract: Low pathogenicity avian influenza virus (LPAIV) and infectious bronchitis virus (IBV) can produce mild to moderate upper respiratory disease in chickens that can be aggravated by other factors including other respiratory pathogens. Since commercial chickens are commonly exposed to other respiratory pathogens, including Mycoplasma synoviae (MS), we studied the dynamics of LPAIV-IBV-MS co-infections in chickens and the effect of co-infection on disease presentation. Three-week-old Specific Pathogen Free (SPF) leghorn chickens were inoculated with MS followed five days later with a LPAIV (Mexican lineage H5N2) and/or an IBV virulent field strain (Ark99). Mild conjunctivitis was the only clinical sign observed in the LPAIV-inoculated birds. Moderate to severe conjunctivitis was present in all birds inoculated with IBV or MS. In addition to conjunctivitis, birds co-infected with MS+IBV or MS+IBV+LPAIV had rales, swollen heads, and at necropsy, pinpoint hemorrhages and exudate in the trachea. Birds inoculated with LPAIV and/or IBV had moderate microscopic lesions in the trachea. These lesions were more severe in birds inoculated with MS, and especially severe in birds co-infected with MS+LPAIV, MS+IBV or MS+LPAIV+IBV. Co-infection with LPAIV and/or MS decreased IBV shedding, but higher MS shedding was found in co-infected birds compared to birds only infected with MS. In a second study, SPF turkeys were also co-infected with H5N2 LPAIV and MS. Co-infected turkeys appeared sick, their body weights were affected, and the birds shed significantly higher titers of LPAIV than the ones only exposed to LPAIV. These co-infection studies highlight the role of avian Mycoplasma in co-infections of poultry with respiratory viruses (LPAIV and IBV) in producing disease and lesions.