The hyaluronic acid capsule of @entity8211 is not required for the development of infection and clinical XXXX .

@entity4023 @entity291 @entity1271 @entity8211
The frequency at which the genes responsible for capsule biosynthesis occurred in field isolates of @entity8211 was determined. Of the two genotypes detected (hasABC and hasC), the capsular genotype (hasABC) was more common. This genotype was present at a higher frequency in a population isolated from @entity1271 cases than in a population isolated from @entity291 bedding. The virulence of a mutant strain of @entity8211 (TRF0-6) that lacked the ability to produce a @entity4023 capsule due to an insertion within its single copy of hasA (P. N. Ward, T. R. Field, W. G. F. Ditcham, E. Maguin, and J. A. Leigh, Infect. Immun. 69:392-399, 2001) was compared to that of the capsular parental strain (0140J). Strains TRF0-6 and 0140J infected all mammary gland quarters following experimental challenge. The wild type and the mutant induced overt signs of disease in four out of four and in six out of eight mammary gland quarters, respectively. Both the wild type and the hasA mutant were resistant to killing by @entity291 neutrophils following cultivation in @entity291 milk. The ability to withstand the bactericidal action of neutrophils following growth in milk was therefore independent of the capsule and coincided with the ability of supernatants from such cultures to prevent the bactericidal action of neutrophils. This investigation revealed that, in the absence of the capsule, @entity8211 is able to withstand the bactericidal effect of @entity291 neutrophils and induce @entity1271 in dairy @entity291 .
