Serology of Campylobacter fetus ss. jejuni )"related" campylobacters). Demonstration of strain-specific and interstrain-related antigens by immunoelectrophoresis and co-agglutination.

Rabbit antisera against two strains of Campylobacter fetus ss. fetus (serotype A), two strains of C. fetus ss. intestinalis (serotypes A and B respectively), and eight stains of C. fetus ss. jejuni were used in serological studies of these strains with the use of co-agglutination (COA), line-rocket immunoelectrophoresis (L-RIE) and rocket-line immunoelectrophoresis (R-LIE). Whole bacterial cells, either heated at 56 degrees C. boiled or atuoclaved, were used in COA tests. Unheated sonicates were used in L-RIE, and sonicates, unheated, boiled or autoclaved, in R-LIE. The antigenic properties of C. fetus ss. fetus and C. fetus ss. intestinalis were distinctly different from those of the thermophilic C. fetus ss. jejuni strains as shown both by COA and L-RIE. Serotypes A and B of the two former species were also differentiated. In COA tests the C. fetus ss. jejui=ni organisms gave the strongest reactions with homologous antibodies, but several interstrain cross-reactions were seen. By absorption strain specific COA reagents were obtained. Several reactions of identity indicating cross-reactive antigens were also seen with L-RIE within the ss. jejuni group. These results generally agreed with those obtained by COA. With the use of unheated, boiled or autoclaved organisms or sonicates heat labile antigens were differentiated from heat stable ones with the use of COA and R-LIE. The apparent antigenic heterogeneity of Campylobacteria indicates the importance of their serological grouping, e.g. for clinical and epidemiological investigations. COA and immunoelectrophoresis techniques can be effectively applied for such studies.