Immunoadsorbent-purified antibodies in the study of antigenic relatedness of outer membrane proteins of enteric bacilli.

Immunoadsorbent chromatography was used for purification of antibodies to E. coli 055 outer membrane proteins. Antibodies to the 33.5 kD and 7.5 kD proteins were eluted when rabbit antisera were applied to an epoxy-activated Sepharose 6B column to which the outer membrane was coupled in the presence of dioxane. ELISA coats prepared with sonicated bacteria showed binding of the eluted antibodies with strains of all of seven different species of the enteric bacilli, but not with other Gram-negative bacilli or cocci, or with Gram-positive cocci; immunoblot analysis of transblots of SDS-PAGE-separated bacteria showed that antibodies to both of the 33.5 kD and 7.5 kD E. coli outer membrane proteins cross-reacted with the enteric bacilli of different species. Both of the anti-33.5 kD and -7.5 kD antibodies were bound by intact E. coli 055 cells, but more efficiently by sonically disrupted or heat-treated bacteria. The results show that affinity-purified anti-OM antibodies were useful for the study of the antigenic relatedness of E. coli OM proteins with proteins of other bacteria.