To evaluate the CRMOX virulence test with Yersinia enterocolitica, in-vitro invasiveness and cytotoxicity of bacteria to HeLa, Vero, Hep-2 and rabbit liver cells(RL), were examined with CRMOX-positive and-negative cultures grown at 26℃ and 37℃.
Of 39 strains of bacteria grown at 26℃, 32(82.1%) were invasive to RL, 25(64.1%) to HeLa and Vero, 19(48.7%) to Hep-2, respectively, whereas invasiveness of bacteria grown at 37℃ markedly reduced:20 (51.3%) to RL, 9(23.1%) to Vero, 8(20.5%) to
Hep-2
and 6(15.4%) to HeLa, respectively. In the cytotoxicity of bacteria grown at 26℃, 25(64.1%) were cytotxic to Hep-2, 24(61.5%) to vero, 20(51.3%) to RL and 17(43.6%) to Hela, respectively, buty the similarity of cytotoxicity of bacteria grown at
37%
appeared:22(56.4%) to Hep-2 and Vero, 18(46.2%) to HeLa and 7(17.9%) to RL, respectively. CRMOX-positive reaction was closely related to the invitro cell cytotoxicity and in-vivo mouse infecitivity but not to in-vitro cell infectivity.
CRMOX-positive
bacteria, of which 40 Mdal plasmid was cured by treatment with acridine orange, expressed CRMOX- negative and resulted in decrease of their in-vitro cytotoxicities and loss loss of the 220 Kdal outer membrane proteins.
These results indicated that the in-vitro cytotoxicity of Y. enterocolitica is mediated by 40 Mdal plasmid and closely associated with the CRMOX-positive reaction.
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