Differentiation of Bacteroides nodosus biotypes and colony variants in relation to their virulence and immunoprotective properties in sheep.
AUTOR(ES)
Skerman, T M
RESUMO
To obtain a wider definition of variation in the virulence of Bacteroides nodosus and in the protective potency of B. nodosus vaccines, we made a comparison of the in vitro characteristics of isolates from clinical infections of sheep and cattle and of certain colony variants observed previously. Three basic colony types were distinguished: papillate or beaded (B)-type colonies were produced by fresh isolates from advanced ovine foot rot; mucoid (M)-type colonies were formed by isolates from noninvasive B. nodosus infections of the interdigital skin of sheep and cattle, and also by cultures of some primary B-type colonies passaged nonselectively in vitro; and circular (C)-type colonies were formed by B. nodosus that eventually predominated in repeatedly passaged liquid subcultures. Each type could be maintained by selective agar subculturing; one strain was thus passaged 40 times as the B-type colony, at which point the organisms induced severe foot rot in experimentally infected sheep. Cultures of M-type colonies were uniformly less pathogenic and those of C-type colony organisms were avirulent. In vitro changes from prototype B-type colonies to M- and C-variants were nonreversible in these experiments, were accelerated in liquid cultures, and wee accompanied by a diminution in elastase activity of the organisms and in their immunoprotective properties against homologous challenge. Strains differed in their stability to these changes; therefore the choice of an appropriate strain and colony type may be an important consideration in studies of B. nodosus virulence and in the development of effective vaccines.
ACESSO AO ARTIGO
http://www.pubmedcentral.nih.gov/articlerender.fcgi?artid=351514Documentos Relacionados
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