Salmonella cytotonic and cytolytic factors: their detection in Chinese hamster ovary cells and antigenic relatedness

Thirty nine strains of Salmonella belonging to 14 different serotypes were screened for the production of cytotonic and cytolytic factors by assayed Chinese hamster ovary (CHO) cells. The cell-free culture supernatants (CFCS) of 32 isolates caused elongation and increase in size of CHO cells while the CFCSs completely lysed the cells. The cytotonic effect in CHO cells correlated precisely with fluid accumulation in the rabbit ligated ileal assay in that 24 isolates yielded positive results in both assays and 13 were found negative in both. Antiserum to S. typhimurium enterotoxin, but not that to cholera toxin or Shiga toxin, neutralized the cytotonic activity present in the CFCS and reacted with the latter in immunodiffusion and coagglutination tests. The cytolytic factor produced by two strains reacted neither with antiserum to Salmonella enterotoxin nor with that the Shiga toxin.