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Isolation and Characterization of a 6/85-like Mycoplasma gallisepticum from Commercial Laying Hens

Steinlage, S.J. Thorne, Ferguson, N., Sander, J.E., García, M., Subramanian, S., Leiting, V.A., Kleven, S.H.
Avian diseases 2003 v.47 no.2 pp. 499-505
DNA, Mycoplasma gallisepticum, agglutination, air sacs, antibodies, bird diseases, blood serum, eggs, flocks, laying hens, mortality, nucleotide sequences, random amplified polymorphic DNA technique, sequence analysis, serology, sinuses, vaccines
Eighty-three-week-old table egg layers with swollen sinuses were presented with a history of increased mortality. Serology revealed positive titers to Mycoplasma gallisepticum (MG). The birds were part of a flock in which some birds had been vaccinated with 6/85 live MG vaccine at 18 wk of age. Tracheal cultures were obtained from both vaccinated and unvaccinated birds within the flock. The cultures were indistinguishable from 6/85 vaccine by both random amplified polymorphic DNA analysis and DNA sequence analysis. Challenge studies were performed to compare the field isolates with 6/85 vaccine and the R strain of MG. The field isolates produced a greater antibody response by serum plate agglutination than did the 6/85 vaccine. The isolates effectively colonized the trachea without increasing the tracheal mucosal thickness; however, they did not extensively colonize the air sacs or cause airsacculitis in the experimental birds.