Relationship of HeLa cell infectivity to biochemical, serological, and virulence characteristics of Yersinia enterocolitica

Abstract

Examination of 69 strains of Y. enterocolitica which represented 20 serotypes and nontypable isolates for HeLa cell infectivity by a roller tube technique that provided a quantitative index of infection showed that infectivity (index, > 3.50) was confined to strains of serotypes O:8, O:3, O:5,27, 0:9, O:1, O:1,2,3, O:2,3 O:4,32 and O:21. All strains that were HeLa positive were sucrose positive and negative for salicin, esculin, rhamnose, raffinose, melibiose, .alpha.-methylglucoside and citrate. All HeLa-negative strains were either sucrose and salicin positive or were sucrose negative. There were 21 strains examined for virulence by the ability to produce guinea pig conjunctivitis and diarrhea in mice. Positive strains were limited to those that were HeLa positive and were autoagglutination positive and Ca dependent at 35.degree. C. There was no association between virulence and the ability to produce enterotoxin measured by the infant mouse assay. Loss of autoagglutinability and Ca dependency was accompanied bv loss of virulence, but HeLa cell infectivity was unchanged. Evidently, at least 2 properties are necessary for virulence: the presence of the V and W antigens, mediated by the same plasmid as autoagglutination and Ca dependency and an invasive factor demonstrated in vitro by HeLa cell infectivity. These virulence properties are found in only certain biotypes of Y. enterocolitica.