Peroral Immunization of uropathogenic Escherichia coli Adhesin protein Linked to heat-labile E. coli enterotoxin A2B Subunits
Division of immunopharmacology, Collegy of Pharmacy, Sungkyunkwan University, Suwon, South Korea
Aim: The FimH subunit of type 1-fimbriated uropathogenic Escherichia coli (UPEC) has been determined as a major cause for urinary tract infections. The chimaeric construct adhesin-LTXA2B derived from UPEC FimH adhesin genetically coupled to heat-labile E. coli enterotoxin (LTX) subunits A2 and B (LTXA2B) was expressed in E. coli as an soluble recombinant chimaeric protein. We have evaluated the efficacy of a possible vaccine antigen, FimH adhesin-LTXA2B chimaeric protein, against urinary tract infections. Method: The protein was purified by osmotic shock and affinity chromatography. The composition of purified FimH adhesin-LTXA2B was verified by SDS/PAGE and Western blotting with antibodies to antigenic components of FimH adhesin and LTXB, and confirmed as a chimaeric protein with GM1 ganglioside binding activity and FimH adhesin epitopes by a GM1-ELISA developed using antibodies to FimH adhesin. Result: Oral immunization of mice with FimH adhesin-LTXA2B induced higher level of mucosal IgA and serum IgG antibodies to FimH adhesin and to LTXB than in mice immunized with FimH adhesin or LTXA2B alone. FimH adhesin-LTXA2B was also demonstrated to be potential protective and therapeutic antigens in a mouse model infected with uropathogenic E. coli J96, whereas FimH adhesin and LTXA2B were not able to confer protection and therapy to mice. Conclusion: This protection and therapy may be correlated with level of mucosal IgA and serum IgG antibodies against FimH adhesin. Taken together, the results indicated that the genetically linked LTXA2B acts as a useful mucosal adjuvant, and that the FimH adhesin-LTXA2B chimaeric protein could be a potential component in future UPEC vaccine development.
Paper presented at the International Symposium on Predictive Oncology and Intervention Strategies; Nice, France; February 7 - 10, 2004; in poster session 991 (Synergistic therapies).