Antibody against recombinant heat labile enterotoxin B subunit (rLTB) could block LT binding to ganglioside M1 receptor

Enterotoxigenic Escherichia coli (ETEC) is one of the most common agents of diarrhea among other bacterial agents. Designing and producing vaccine against these bacteria is one of the major purposes of World Health Organization (WHO). Due to presence of diverse clones of ETEC strains in the world, the use of global vaccines for ETEC infection is controversial. B subunit of heat labile toxin (LTB) was introduced as a vaccine candidate molecule by several investigators. The expression of LTB gene isolated from a local bacterial strain and investigation of its immunological property was the objective of this study. LTB gene was isolated from a local isolated ETEC, cloned and expressed using pET28a expression vector. For LTB gene expression, the three main expression parameters (IPTG concentration, time and temperature of induction) were investigated. The recombinant protein was purified (> 95%) with Ni-NTA column using 6XHis-tag and used as an antigen in ELISA test. The immunological analyses showed production of high titer of specific antibody in immunized mice. Anti LTB Antibody could bind to whole toxin and neutralize the toxin through inhibition of its binding to the Ganglioside M1 receptor. The recombinant LTB protein is a highly immunogenic molecule. Considering the LTB role in ETEC pathogenesis, it can be taken into account as one of the most important components of vaccines against local ETEC.