Temperature-Sensitive Mutant of Mycoplasma synoviae. I. Production and Selection of a Nonpathogenic but Immunogenic Clone

Abstract

Temperature-sensitive (ts) mutants of Mycoplasma synoviae were produced by treating the wild 1-3SN strain with N-methyl-N'-nitro-N-nitrosoguanidine. Twelve ts mutants were selected at 39.5 C as a restrictive and 33 C as a permissive temperature. Among the mutants, MSts44 was proven to be nonpathogenic but immunogenic. MSts44 did not induce airsacculitis in bursectomized or normal chickens, and it was stable after five passages through chicken. Chickens immunized intranasally with MSts44 were protected against airsacculitis for at least 21 weeks. A dose of 10(4.1) colony-forming units or more of the mutant per bird was needed to induce protection in 3-week-old chickens.