1887

Abstract

Mutants of defective in DNA adenine methylase () have been reported to be attenuated for virulence and to provide protective immunity when used as vaccine strains. To determine whether these observations could be extended to , a mutant of 2a was characterized and examined for the role of in pathogenesis. The mutant showed some unique characteristics; however, it retained virulence as well as . The mutant invaded cultured L2 monolayer cells as efficiently as the wild-type parent, but its intracellular growth was suppressed up to 7 h post-invasion. Furthermore, the invading mutant formed smaller plaques in cell monolayers compared to the parent strain. However, the mutant produced keratoconjunctivitis in the Sereny test in guinea pigs only slightly more slowly than the wild-type. While the effect of the mutation on virulence was modest, the rate of spontaneous mutation in the mutant was 1000-fold greater compared with the wild-type. The virulence and high mutability displayed by the mutant of suggest that a general anti-bacterial pathogen vaccine strategy based on mutations in needs to be re-evaluated.

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2004-04-01
2024-04-18
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