Temperature-Sensitive Mutants of Mycoplasma pneumotuae. II. Response of Hamsters

Abstract

For development of an attenuated live vaccine strain of Mycoplasma pneumoniae, temperature-sensitive (ts) mutants were produced by treatment of the PI 1428 strain with N-methyl-N′-nitro-nitrosoguanidine. Eight of the nine mutants studied infected the hamster's respiratory tract, but these mutants were recovered significantly less often than wild-type organisms which were studied for comparative purposes. The ts mutants as a group were attenuated since they produced virtually no pneumonia, whereas wild-type organisms produced pneumonia in 50%–65% of inoculated animals. The ts mutants did not revert to wild type in vivo during a six-week period of observation. Infection with the mutants induced significant resistance to subsequent challenge with wild-type organisms. These findings offer some hope for eventual control of illness due to M. pneumoniae with a live vaccine.