Immunochemistry of Yersinia enterocolitica O3 grown at different temperatures.

Comparative agglutinations of homogeneous stable suspensions prepared with Yersinia enterocolitica growth at 37 degrees C and at 25 degrees C were performed with anti-sera prepared in rabbits with the bacteria grown at both these temperatures. Sera prepared with live Y. enterocolitica grown at 37 degrees C agglutinated both suspensions at a much lower titre than the sera prepared with formaldehyde-treated bacteria is grown at 25 degrees C. All the sera in which strongly precipitating antibodies were induced reacted, in agar-gel, against native and heated proteins. The small amounts of antipolysaccharides induced in all the sera reacted only in the ring test against the bacterial polysaccharides. The absorption of the sera prepared with live Y. enterocolitica grown at 37 degrees C, with antigens synthesized at 25 degrees C did not remove all the homologous antibodies; apparently, some determinants are specific for the bacteria grown at 37 degrees C. Morphological changes of the small rods to elongated bacilli and filamentous forms were observed in most cultures of the Y. enterocolitica grown at 37 degrees C; these changes coincided with a low yield of proteins and point to an inhibitory effect of the 37 degrees C temperature.