Thesis (M.Sc.)--Chulalongkorn University, 2008

Monoclonal antibodies (MAbs) against Yersinia enterocolitica, a foodborne pathogen causing gastroenteritis and other complications known as yersiniosis, were produced and characterized. Hybridomas were produced by fusion NS-1 mouse myeloma cells with spleen cells of ICR mouse immunized with heat-killed and SDS-mercaptoethanol treated form of Y. enterocolitica ATCC 27729 or mixed with MU isolate. Screening of hybridomas producing antibody against Y. enterocolitica was performed by dot blotting. Twenty-five MAbs were obtained from five fusions and can be divided into 9 groups according to their specificities to several bacterial strains as determined by dot blotting. The first five groups of MAbs were specific only to Y. enterocolitica, but not recognized all isolates tested. MAbs in group 6 and group 7 reacted with all isolates of Y. enterocolitica tested and also showed cross-reaction with some Yersinia spp. and Edwardsiella tarda, especially for group 7. MAbs in group 8 and group 9 reacted with all isolates of Y. enterocolitica and Yersinia spp. as well as other Gram-negative bacteria which belong to Enterobacteriaceae. These MAbs recognized Y. entericolitica at molecular weight ranging from 10-43 kDa by Western blotting and could detect Y. enterocolitica within the range from approximately 106-108 CFU ml-1 by dot blotting depending on the group of MAbs. The major isotype of the MAbs was IgM and the remaining MAbs were determined as various groups of IgG isotypes. Some of MAbs produced in this study would be used as a tool in immunological-based methods for specific detection of Y. enterocolitica in food or clinical samples.