Abstract

Enterotoxigenic Escherichia coli (ETEC) is the most significant agent leading to childhood diarrhea and death in developing countries. This bacterium is the cause of 380 thousand deaths in children under five years of age. Due to its prevalence as well as difficulties in its treatment, designing effective vaccines against ETEC is a goal of the World Health Organization (WHO). The Colonization factor B (CfaB) as major subunit of fimberiae has a critical role in bacterial attachment to small intestine epithelium. Hence, the molecule alone or together with other candidate molecules has been considered in vaccine design. In this work, we produced recombinant CfaB in E. coli with the aim of studying its immunogenicity as a component of vaccine. The cfaB gene was cloned into pET28a and regarding the presence of rare codons in cfaB gene, it was not expressed. Therefore, an optimized gene with codon preferences was synthesized and cloned into pET28a vector and subsequently expressed. The recombinant protein was purified with Ni-NTA column and used as an antigen for mice immunization and in ELISA test. Microplate agglutination inhibition test was utilized to show antibody blocking activity. In conclusion, codon optimization is a useful approach for obtaining large quantities of a desired protein. Relying on agglutination inhibition experiment, anti-CfaB serum was able to block the binding of colonization factor antigen I (CFA/I) fimbriated ETEC to erythrocytes.

Key words: Enterotoxigenic Escherichia coli (ETEC), colonization factor antigen I, expression, agglutination inhibition