title: An antiphagocytic factor associated with group E streptococcus.
abstract: Group E streptococci (GES) grown in Tryptose phosphate broth (TPB) were highly susceptible to nonspecific phagocytosis by porcine leukocytes, whereas GES grown in serum-supplemented TPB (STPB) were resistant to nonspecific phagocytosis. It was concluded that serum supplementation induced the elaboration of an antiphagocytic factor (APF). The APF was distinct from the group-specific and type-specific polysaccharide antigens, and it was destroyed by trypsin. Electron photomicrographs revealed that GES grown in STPB possessed a fimbriated surface component similar to M protein-positive stains of group A streptococcus. The surface component was absent when GES were propagated in unfortified TPB. The APF was neutralized specifically by sera from swine immune to streptococcic lymphadenitis (SLS), a disease caused by GES. It was hypothesized that the APF was associated with the pathogenicity of GES and that it was involved in the induction of protective immunity to SLS.
mesh_terms: D000818:Animals; D001431:Bacteriological Techniques; D003470:Culture Media; D007106:Immune Sera; D007109:Immunity; D008199:Lymphadenitis / Q000276:immunology; D008854:Microscopy, Electron; D010587:Phagocytosis; D013291:Streptococcus / Q000276:immunology*; D013552:Swine; D013553:Swine Diseases / Q000276:immunology; D014357:Trypsin / Q000494:pharmacology
chemical_list: D003470:Culture Media; D007106:Immune Sera; D014357:Trypsin