Jw. Cherwonogrodzky et al., INCREASED ENCAPSULATION AND VIRULENCE OF FRANCISELLA-TULARENSIS LIVE VACCINE STRAIN (LVS) BY SUBCULTURING ON SYNTHETIC MEDIUM, Vaccine, 12(9), 1994, pp. 773-775
Francisella tularensis live vaccine strain (LVS), taken directly from
lyophilized vials, did not appear to have a capsule and had low virule
nce for balb/c mice. When this strain was subcultured on Chamberlain's
synthetic medium (pH 6.5), it became extensively capsulated (1-5 mu m
in diameter) and its virulence for Balb/c mice increased about 1000-f
old. We conclude that the virulence of the attenuated vaccine strain,
F. tularensis LVS, may still be influenced by growth conditions.