Evaluation of the egg transmission and pathogenicity of Mycoplasma gallisepticum isolates genotyped as ts-11.
Live Mycoplasma gallisepticum vaccines are used for the control of respiratory disease, egg production losses and egg transmission associated with M. gallisepticum infection in long-lived poultry. The first field case of apparent increased virulence and vertical transmission of ts-11, a live M. gallisepticum vaccine, has been reported. In that study a M. gallisepticum isolate from the broiler progeny of ts-11-vaccinated breeders was genotyped as ts-11 by sequence analysis of four different genetic targets and Random Amplified Polymorphic DNA and found to be significantly more virulent than ts-11 vaccine. The objective of the current study was to evaluate the rate of egg transmission and pathogenicity of ts-11 vaccine and isolates recovered from ts-11-vaccinated breeders (K6222B) and their broiler progeny (K6216D) which had been genotyped as ts-11. Groups of 28-week-old specific pathogen-free chickens at 87% average weekly egg production were inoculated with sterile broth media (negative controls), ts-11 vaccine, K6222B, K6216D or R strain (positive controls) by eye-drop and aerosol. K6216D transmitted via the egg at an average rate of 4.0% in the third and fourth weeks post-infection, while egg transmission of K6222B and ts-11 vaccine was not detected. M. gallisepticum was isolated from the air sacs, ovaries and oviducts of hens infected with K6216D and K6222B, but not from those infected with ts-11 vaccine. K6216D and K6222B both induced respiratory signs and significantly more tracheal colonization and more severe tracheal and air sac lesions than ts-11 vaccine (P ≤ 0.05). There were no substantial differences in the egg production of ts-11, K6216D and K6222B infected groups. These results provide the first conclusive evidence of transovarian transmission of an isolate genotyped as ts-11 and indicate that isolates genotyed as ts-11 vary in their virulence and ability to transmit via the egg.
a Department of Population Health , University of Georgia , Athens , GA , USA.
Natalie K
NK
Armour
Naola
N
Ferguson-Noel
D000400:Air Sacs / Q000382:microbiology; D000818:Animals; D001428:Bacterial Vaccines / Q000276:immunology*; D002645:Chickens / Q000382:microbiology*; D005260:Female; D005838:Genotype; D008297:Male; D009175:Mycoplasma Infections / Q000517:prevention & control / Q000635:transmission / Q000662:veterinary*; D045686:Mycoplasma gallisepticum / Q000276:immunology* / Q000472:pathogenicity; D010063:Ovum / Q000382:microbiology; D011201:Poultry Diseases / Q000517:prevention & control / Q000635:transmission*; D013047:Specific Pathogen-Free Organisms; D014132:Trachea / Q000382:microbiology; D014613:Vaccines, Attenuated / Q000276:immunology; D014774:Virulence
D001428:Bacterial Vaccines; D014613:Vaccines, Attenuated