Monoclonal antibodies to distinguish between Shiga toxin-producing E. coli O157 and O145 serogroups

CASTILLO DS; REY SERANTES D; MELLI L; CIOCCHINI A; UGALDE JE; COMERCI D; CASSOLA A

Córdoba

Congreso; LII Reunión Anual Sociedad Argentina de Investigación en Bioquímica y Biología Molecular; 2016

Shiga-toxin producing Escherichia coli (STEC) strains are causal agents of bloody diarrhea (BD) and hemolytic-uremic syndrome (HUS). HUS is caused by particular strains of STEC in Argentina, being E. coli O157 the predominant serogroup (70%), followed by E. coli O145 (9%). Here, we have developed specific monoclonal antibodies against E. coli O157 and O145 serogroups using a combined strategy of adjuvated-bacterial immunizations, followed by immunizations with soluble engineered O-polysaccharide-protein conjugates. We obtained 18,8% and 13,3% of positive and specific hybridoma populations to O157 and O145 O-polysaccharide-protein conjugates, respectively. These O-polysaccharide-protein conjugates also allowed the screening of monoclonal antibody (mAb)-producing hybridoma populations and their cloning without interference of other LPS antigenic portions. We selected three specific hybridoma clones for O157 (1E10, 3F10 and 10G2) and three for O145 (2H6, 4C8 and 4E6). All the mAbs showed specific binding to the sought O-polysaccharide section of the LPS by Western blot. Whole cell ELISA of heat-killed bacteria also showed specific binding to O157 and O145 serogroups, but no binding to other STEC or to a non-toxic E. coli strain was detected. These mAbs are of considerable value for the development of detection and diagnosis assays against STEC.