Structural and biological studies on the surface antigens involved in the pathogenesis of Campylobacter gastro-enteritis

Abstract

The outer membranes of C.jejuni and C.coli were isolated by two methods, spheroplast formation and detergent solubilization of the inner membrane. Membranes prepared by either procedure were essentially similar. Two main protein bands predominated in the outer membranes. A variable molecular weight protein of M.wt 43-46,000 represented the major band in total protein profiles, it was heat-modifiable and surface exposed. The second band had a M.wt in the range 62-64,000 it was not heat-modifiable and was identified as flagellin. An acid-extract from the surface of the C.jejuni cells contained 25K and 27K proteins. Staining of OM proteins with Schiff's reagent revealed staining in the 27-30K region and probably represented LPS. The techniques of radio-immunoprecipitation and immunoblotting were used to examine the antigenicity of C.jejuni proteins. Both the 43K Momp and the 63K flagellin proteins were immunogenic. Different flagellins elicited antibodies that showed either broad or limited cross-reactivites. The biological role of Elagella was investigated by the isolation of an flagellate non-motile variant (SFl) and an aflagellate variant (SF2) from C.jejuni 81116. The amino-acid compositions of the flagellins were essentially identical to those of other known bacteria. Attachment studies to erythrocytes of various species revealed differences in the attachments of 81116 and the variants. It is proposed that attachment to RBC is through a surface adhesin and that active and to a lesser extent inactive flagellla blocked this attachment. Adsorption isotherm data supported this view. In contrast attachment to eukaryotic cells was considerably lower compared to RBCs. However it is possible that an adhesin resides on the flagella producing a tenuous attachment to cell surfaces. Specificity to a cell line of intestinal origin was observed. The three strains were examined jji vivo using an infant mouse model for colonization. The possession of flagella and not motility was the major factor in successful colonization.

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