A universal polysaccharide conjugated vaccine against O111 E. coli

Area of Science:

• Microbiology
• Immunology
• Vaccine Development

Background:

• E. coli O111 strains cause severe diarrheal diseases globally.
• Phenotypic variability of E. coli O111 complicates vaccine development.
• O111 lipopolysaccharide (LPS) is a potential target but is toxic for human use.

Purpose of the Study:

• To develop a safe and effective vaccine targeting a common antigen in E. coli O111 strains.
• To evaluate the immunogenicity and efficacy of O111 polysaccharide conjugates using different delivery systems.

Main Methods:

• O111 polysaccharides were conjugated to carrier proteins: cytochrome C and EtxB (recombinant B subunit of LT).
• Conjugates were incorporated into silica SBA-15 nanoparticles (O111-cytochrome C) and Vaxcine™ (O111-EtxB).
• Subcutaneous and oral immunizations were performed in rabbits and mice, respectively, followed by antibody analysis and functional assays.

Main Results:

• Silica SBA-15 nanoparticle-delivered conjugate induced antibodies in rabbits that inhibited E. coli O111 adhesion to epithelial cells.
• Oral Vaxcine™-delivered conjugate induced systemic and mucosal humoral responses in mice against all E. coli O111 categories.
• The O111-EtxB conjugate generated antibodies capable of inhibiting LT toxicity in vitro.

Conclusions:

• Vaccines targeting the O111 antigen show potential for preventing diarrhea caused by diverse E. coli O111 strains.
• Conjugated vaccines utilizing EtxB as a carrier protein may combat diarrhea induced by enterotoxigenic E. coli (ETEC).