Analysis and characterization of Mycoplasma gallisepticum isolates from Pennsylvania

Because Mycoplasma gallisepticum F strain vaccine can be pathogenic in chickens and is pathogenic in turkeys, we monitored the spread of MG F strain into unvaccinated flocks by screening field and experimental isolates. Thirteen MG isolates obtained from various sources in Pennsylvania were screened using several techniques capable of differentiating between MG strains. DNA restriction enzyme analysis (REA), Sodium dodecyl sulfate-polyacrylamide gel electrophoresis (SDS-PAGE) protein profiles, non-isotopic DNA probes, and a monoclonal antibody specific for F strain were used to characterize each of the 13 isolates. Three of the 13 isolates were identical to F strain; two of these were obtained from challenge studies, and one was a field isolate from a multiple-age commercial egg farm where the F strain vaccine had been used in the past. The remaining 10 isolates were different from MG F strain but were quite similar if not identical to each other according to REA; SDS-PAGE protein profiles show similarities between the 10 isolates. The results suggested that F strain vaccine is not a major cause of field outbreaks of MG in Pennsylvania.