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Monoclonal Antibodies to the Lipopolysaccharide of Erwinia carotovora subsp. atroseptica Serogroup I. S. H. De Boer, Agriculture Canada, Vancouver Research Station, 6660 N.W. Marine Dr., Vancouver, B.C., Canada, V6T 1X2; M. E. McNaughton, Agriculture Canada, Vancouver Research Station, 6660 N.W. Marine Dr., Vancouver, B.C., Canada, V6T 1X2. Phytopathology 77:828-832. Accepted for publication 27 October 1986. Copyright 1987 Department of Agriculture. Government of Canada.. DOI: 10.1094/Phyto-77-828.

Monoclonal antibodies were produced to an Erwinia carotovora subsp. atroseptica serogroup I strain using outer membrane and soluble antigen extracts as immunogens. Monoclonal antibodies from three different hybridomas reacted with purified lipopolysaccharide. Furthermore, immunoblot analysis of lipopolysaccharide separated on polyacrylamide gels indicated that all three monoclonals reacted with the O-side chain. In immunofluorescence tests, the monoclonals reacted with all 18 E. c. subsp. atroseptica serogroup I strains tested. They also reacted with strains in serogroup XXII, but not with strains in serogroups XVIII and XX. They did not react with any of the 36 E. c. subsp. carotovora or eight E. chrysanthemi strains that were tested. One of the monoclonals was used for the enzyme-conjugate in enzyme-linked immunosorbent assays (ELISA), but this monoclonal did not work for coating the plates. Reaction of bacteria with the monoclonal-enzyme conjugate, however, was considerably lower than reaction with a comparable polyclonal-enzyme conjugate. Nevertheless, the monoclonal could be used in ELISA to differentiate between blackleg-infected and healthy potato stems. Blackleg contamination of symptomless tubers could not be detected by ELISA using the monoclonal-enzyme conjugate.