Correlation of titer, preservation method, and storage of Mycoplasma gallisepticum F strain and the immune response in chickens.

The F strain of Mycoplasma gallisepticum (MG) was used either fresh or after lyophilization or freezing at -60 C to vaccinate young leghorn chickens. Vaccine stored either frozen or lyophilized for 22 months was also used. Each vaccine preparation was given at dosages ranging from 10(5) to 10(9) colony-forming units/ml. All dosage levels of MG significantly (P less than 0.05) reduced air-sac lesion scores after aerosol challenge with the R strain of MG at 6 weeks postvaccination, regardless of the method of vaccine preservation or storage.