Creating a laboratory model of Mycoplasma gallisepticum and Mycoplasma synoviae associated infection

Abstract

Introduction. Respiratory mycoplasmosis and infectious synovitis are economically significant and notifiable avian diseases, therefore, the issue of Mycoplasma gallisepticum and Mycoplasma synoviae control on poultry farms is of great importance. Vaccination is one of the ways to ensure specific prevention, however, when a vaccine is developed, its protective properties are assessed with special focus. Challenge does not always lead to the disease manifestation due to its predominantly chronic and factor-dependant nature.Objective. Laboratory simulation of the factors that contribute to the disease manifestation and a histological analysis of pathological changes in the infected and vaccinated poultry.Materials and methods. Seronegative and vaccinated 67-day-old Haysex white cross chickens were selected for the experimental purposes. We used S6 strain of Mycoplasma gallisepticum, WVU 1853 strain of Mycoplasma synoviae and A/chicken/Amursky/03/12/H9N2 strain of low-pathogenicity avian influenza virus.Results.The associated infection of mycoplasmoses and low-pathogenicity avian influenza is manifested as a disease with pathohistological changes that include mild respiratory and joint disorders. Histological tests of the infected non-vaccinated poultry revealed damaged tracheal ciliated epithelium with desquamation. The poultry vaccinated against mycoplasmosis and experimentally infected showed no signs of epithelial separation, however, local submucosal edema was observed in the trachea. Non-vaccinated poultry infected with low-pathogenicity avian influenza virus H9N2, Mycoplasma gallisepticum and Mycoplasma synoviae demonstrated dystrophic changes and lymphocyte infiltration in the third eyelid gland which suggested an inflammation. Lymphocytic lung tissue infiltration was detected both in the vaccinated and non-vaccinated experimentally infected poultry. All groups of chickens, except for the control one, demonstrated lymphocyte depopulation in the cortical substance of the fabricium sac.Conclusion. The study resulted in developing a challenge procedure for poultry using Mycoplasma gallisepticum and Mycoplasma synoviae agents, in defining conditions for clinical manifestation of mycoplasmoses, in detecting infection-caused pathological changes at the cellular level.

Keywords

• mycoplasma gallisepticum
• mycoplasma synoviae
• histology
• challenge