Secretion of the Shiga toxin B subunit (Stx1B) via an autotransporter protein optimizes the protective immune response to the antigen expressed in an attenuated E. coli (rEPEC E22Δler) vaccine strain.

We previously developed attenuated rabbit enteropathogenic E. coli (rEPEC) strains which are effective oral vaccines against their parent pathogens by deleting ler, a global regulator of virulence genes. To use these strains as orally administered vectors to deliver other antigens we incorporated the B subunit of shiga-like toxin 1(Stx1) into the passenger domain of the autotransporter EspP expressed on a plasmid.

The secreted effector protein EspZ is essential for virulence of rabbit enteropathogenic Escherichia coli.

Attaching and effacing (A/E) pathogens adhere intimately to intestinal enterocytes and efface brush border microvilli. A key virulence strategy of A/E pathogens is the type III secretion system (T3SS)-mediated delivery of effector proteins into host cells. The secreted protein EspZ is postulated to promote enterocyte survival by regulating the T3SS and/or by modulating epithelial signaling pathways.

Attenuated Escherichia coli strains expressing the colonization factor antigen I (CFA/I) and a detoxified heat-labile enterotoxin (LThK63) enhance clearance of ETEC from the lungs of mice and protect mice from intestinal ETEC colonization and LT-induced fluid accumulation.

Although enterotoxigenic Escherichia coli (ETEC) infections are important causes of infantile and traveler's diarrhea there is no licensed vaccine available for those at-risk. Our goal is to develop a safe, live attenuated ETEC vaccine. We used an attenuated E.

A directed intimin insertion mutant of a rabbit enteropathogenic Escherichia coli (REPEC) is attenuated, immunogenic and elicits serogroup specific protection.

We previously showed (Agin et al., 2005) that a truncated beta-intimin mutant of an O15 A/E REPEC strain, which does not contain the C terminal tir binding region of intimin but expresses the preceding immunodominant portion of the molecule in outer membranes, is attenuated, induces anti-intimin and anti whole cell antibody, and protects against challenge with a virulent strain of the same serogroup. Since the ability of this and other intimin mutants lacking the tir binding region to provide broad protection against challenge with REPEC strains of other serogroups is incompletely studied, we generated a targeted insertion/deletion intimin mutant in an O103 strain, immunized rabbit's orogastrically, then challenged them with the parent strain and a virulent strain of a different serogroup.

The encapsulation of enterotoxigenic Escherichia coli colonization factor CS3 in biodegradable microspheres enhances the murine antibody response following intranasal administration.

The aim of this study was to measure serum and mucosal antibody responses following intranasal administration of biodegradable poly(DL-lactide-co-glycolide) (PLGA) microspheres loaded with the CS3 colonization factor isolated from enterotoxigenic Escherichia coli (ETEC). The response was compared against that measured in mice similarly administered the native CS3 antigen and in mice co-administered, along with the CS3 antigen, a known mucosal adjuvant, the R192G mutant heat-labile enterotoxin (mLT). The integrity of the CS3 antigen released from the microspheres was maintained as determined by SDS-PAGE and immunoblotting.

Long-term systemic and mucosal antibody responses measured in BALB/c mice following intranasal challenge with viable enterotoxigenic Escherichia coli.

The immunogenicity induced in BALB/c mice following intranasal challenge with a viable nonlethal dose (1.2 x 10(8) CFU) of enterotoxigenic Escherichia coli (ETEC) strain E23477A (O139:H28:CS1:CS3:LT+:ST+) was studied over a 140-day period. Serum IgG and IgM antibodies against coli surface antigen 3 (CS3), O139 lipopolysaccharide and heat-labile enterotoxin were measured by day 14 and remained at elevated levels out to day 140.

Intranasal immunization of BALB/c mice with enterotoxigenic Escherichia coli colonization factor CS6 encapsulated in biodegradable poly(DL-lactide-co-glycolide) microspheres.

Mice were intranasally administered enterotoxigenic Escherichia coli colonization factor CS6 encapsulated in poly(DL-lactide-co-glycolide) microspheres (CS6-PLG), with immune response measured and compared to that of similarly administered native CS6 and CS6 plus mutant heat-labile enterotoxin mucosal adjuvant (CS6+mLT). Native CS6 and the CS6-PLG microspheres administered intranasally to mice induced serum IgG responses, with the CS6-PLG microspheres inducing a significantly greater (P<0.001) response than native CS6.

Microencapsulated subunit vaccine approach to enterotoxigenic Escherichia coli and other mucosal pathogens.

Infections of the intestinal, urogenital, and respiratory tracts are serious health problems worldwide from both a morbidity and mortality perspective. Mucosal pathogens attach to surfaces of mucosa as a prerequisite for colonization and subsequent pathogenesis. By expressing various surface adhesins (colonization factors, CF) they are able to bind to specific mucosal receptors.

Murine antibody response to intranasally administered enterotoxigenic Escherichia coli colonization factor CS6.

Enterotoxigenic Escherichia coli (ETEC) is the most common cause of bacterial diarrhea worldwide and is an important cause of infant morbidity and mortality in developing nations. ETEC colonization factors (CF) are virulence determinants that appear to be protective antigens in humans and are the major target of vaccine efforts. One of the most prevalent CF, CS6, is expressed by about 30% of ETEC worldwide.

Mucosal immunization of BALB/c mice using enterotoxigenic Escherichia coli colonization factors CFA/I and CS6 administered with and without a mutant heat-labile enterotoxin.

Mice (BALB/c) were intranasally (IN) and intragastrically (IG) administered the ETEC colonization factors (CF), CFA/I and CS6, with and without the R192G mutant heat-labile enterotoxin (mLT), and immunogenicity and efficacy measured. The IN administration of CFA/I to mice induced strong serum and fecal IgG and IgA responses. The IG administration of CFA/I to mice induced serum IgG and fecal IgA responses, but only when mLT was co-administered with CFA/I were serum IgA titers detected.

Pathogenicity and immune response measured in mice following intranasal challenge with enterotoxigenic Escherichia coli strains H10407 and B7A.

The pathogenicity and immunogenicity induced in BALB/c mice by intranasal (i.n.) inoculation of enterotoxigenic Escherichia coli (ETEC) strains H10407 (O78:H11:CFA/I:LT(+):ST(+)) and B7A (O148:H28:CS6:LT(+):ST(+)) (two ETEC strains previously used in human challenge trials) were studied.