EXTRACELLULAR PROTEINS AND VIRULENCE IN STREPTOCOCCUS-BOVIS ISOLATES FROM PIGEONS

The association between virulence and the occurrence of the extracellu lar proteins A, T1, T2 and T3 in the culture supernatant of pigeon Str eptococcus bovis strains, was examined in experimental infection studi es. Fourteen groups of 10-17 pigeons were inoculated intravenously wit h 1 x 10(9) CFU of S. bovis strains that belonged to the phenotypes A( +)T1, A(-)T1, A(+)T2, A(-)T2, A(+)T3 and A(-)T3, respectively. The ove rall postinoculation morbidity in the phenotype groups was 85%, 87%, 7 0%, 5%, 100% and 37%, respectively. These results indicate that strain s producing A or T1 are of high virulence, those producing T3 only are of moderate virulence and those producing T2 are of low virulence. Vi rulence of S. bovis for pigeons was more clearly correlated with super natant-phenotype than with serotype. (C) 1997 Elsevier Science B.V.