Escherichia coli antibodies in opsonisation and protection against infection.

The opsonic and protective capacities of rabbit antisera against Escherichia coli O, K and core-glycolipid cell-wall antigens were compared with specific antibody titres as measured by agglutination and enzyme-linked immunosorbent assay. Anti-O antisera were opsonic and protective against two noncapsulate strains. Only anti-K antisera were opsonic and protective against a K-antigen-containing strain. In a mouse model anti-core-glycolipid antiserum was not protective against challenge even by a strain bearing only core glycolipid.