Monoclonal antibodies for detection of the H7 antigen of Escherichia coli.
Two murine monoclonal antibodies (MAbs) (2B7 and 46E9-9) reactive with the H7 flagellar antigen of Escherichia coli were produced and characterized. A total of 217 E. coli strains (48 O157:H7, 4 O157:NM, 23 O157:non-H7, 22 H7:non-O157, and 120 non-O157:nonH7), 17 Salmonella serovars, and 29 other gram-negative bacteria were used to evaluate the reactivities of the two MAbs by indirect enzyme-linked immunosorbent assay (ELISA). Both MAbs reacted strongly with all E. coli strains possessing the H7 antigen and with H23- and H24-positive E. coli strains. Indirect ELISA MAb specificity was confirmed by inhibition ELISA and by Western blotting (immunoblotting), using partially purified flagellins from E. coli O157:H7 and other E. coli strains. On a Western blot, MAb 46E9-9 was more reactive against H7 flagellin of E. coli O157:H7 than against H7 flagellin of E. coli O1:K1:H7. Competition ELISA suggested that MAbs 2B7 and 46E9-9 reacted with closely related H7 epitopes. When the ELISA reactivities of the MAbs and two commercially available polyclonal anti-H7 antisera were compared, both polyclonal antisera and MAbs reacted strongly with E. coli H7 bacteria. However, the polyclonal antisera cross-reacted strongly both with non-H7 E. coli and with many non-E. coli bacteria. The polyclonal antisera also reacted strongly with H23 and H24 E. coli isolates. The data suggest the need to define serotype-specific epitopes among H7, H23, and H24 E. coli flagella. The anti-H7 MAbs described in this report have the potential to serve as high-quality diagnostic reagents, used either alone or in combination with O157-specific MAbs, to identify or detect E. coli O157:H7 in food products or in human and veterinary clinical specimens.
He
Y
Y
U.S. Meat Animal Research Center, U.S. Department of Agriculture, Clay Center, Nebraska 68933, USA. he@aux.marc.usda.gov
Keen
J E
JE
Westerman
R B
RB
Littledike
E T
ET
Kwang
J
J
D000818:Animals; D000911:Antibodies, Monoclonal / Q000276:immunology*; D000918:Antibody Specificity; D000942:Antigens, Bacterial / Q000032:analysis*; D003429:Cross Reactions; D004797:Enzyme-Linked Immunosorbent Assay; D004926:Escherichia coli / Q000276:immunology*; D051379:Mice; D008807:Mice, Inbred BALB C; D012703:Serotyping
D000911:Antibodies, Monoclonal; D000942:Antigens, Bacterial