Abstract: Enterotoxic Escherichia coli (ETEC) can cause acute diarrhea in human and animals, and its key virulent factor is heat-stable enterotoxin (ST).ST is a peptide with small molecular weight and great toxicity but without immunogenicity, so how to keep its immunogenicity and reduce its toxicity has become a hot research topic for preparing ST toxoid vaccine.In this study, rabbit serum albumin (RSA) was purified by rivanol method and activated in 0.2% glutaraldehyde solution before RSA was conjugated to synthetic methanol-soluble STa, SDS-PAGE result showed that an approximate 108.5 ku complete antigen was obtained.New Zealand White rabbits were immunized with the conjugate four times, the serum was then collected and used to purify immunoglobulin by immunoprecipitation with Protein A/G Plus-Agarose.Dot-ELISA and Western blotting result showed that the titer of the antiserum both reached 1:400.These results indicated that anti-STa polyclonal antibody was successfully prepared, which provided the way for screening of ST structure analogues.

Key words: heat-stable enterotoxin (ST); conjugate; polyclonal antibody