• Vaccine Name: E. coli vaccine based on recombinant protein CO393
• Target Pathogen: Escherichia coli
• Target Disease: Hemorrhagic colitis
• Tradename: None
• Vaccine Ontology ID: VO_0000485
• Type: Subunit vaccine
• Antigen: C0393 protein associated with ExPEC strains (Durant et al., 2007).
• C0393 gene engineering:
  • Type: Recombinant protein preparation
  • Description:
  • Detailed Gene Information: Click Here.
• Adjuvant:
  • Adjuvant name:
  • VO adjuvant ID: VO_0000139
  • Description: Recombinant protein was emulsified in complete Freund's adjuvant (Sigma) during innoculation, but emulsified in incomplete Freund's adjuvant during boosting (Durant et al., 2007).
• Adjuvant:
  • Adjuvant name:
  • VO adjuvant ID: VO_0000142
  • Description: Recombinant protein was emulsified in complete Freund's adjuvant (Sigma) during innoculation, but emulsified in incomplete Freund's adjuvant during boosting (Durant et al., 2007).
• Preparation: The chromosomal DNA of strain S26 was used as the source of DNA for expression of predicted surface antigens. PCR was performed. After purification, the PCR products were introduced into plasmid expression vectors to generate proteins fused with His6. The resulting plasmids were introduced into E. coli BL21 Star (DE3) (Invitrogen, Carlsbad, CA). For protein expression, overnight cultures were used to inoculate a fresh LB medium supplemented with ampicillin (100 µg/ml). Bacteria were grown and then harvested by centrifugation. Purification of recombinant proteins was performed by affinity chromatography . Fractions containing the recombinant protein were pooled and concentrated (Durant et al., 2007).
• Virulence: Not noted.
• Description: In terms of biological significance to humans, E. coli strains are grouped into three categories: (i) commensal strains that represent a large part of the normal flora, (ii) intestinal pathogenic strains that cause diseases when ingested in sufficient quantities, and (iii) pathogenic strains causing extraintestinal infections (extraintestinal pathogenic E. coli [ExPEC]). Recently, the resistance of the ExPEC strains to various classes of antibiotics has become a major concern both in hospitals and in the community. Vaccines represent a rational alternative approach for the prevention of these infections. In this case, the challenge is to selectively prevent a subtype of E. coli strains that is not normally part of the commensal flora. Therefore, it is of great importance to find some specific genetic traits of these ExPEC strains. The current study identifies putative antigens from ExPEC-specific genomic sequences. In an animal model of lethal sepsis, the protective effect of immunization with these antigens was demonstrated, allowing the identification of five antigens as vaccine candidates against an extraintestinal E. coli infection (Durant et al., 2007).

Mouse Response

• Host Strain: 6-week-old BALB/c@Rj mice (Janvier Laboratories, France).
• Vaccination Protocol: Purified recombinant proteins were used to immunize groups of mice. Each mouse was injected s.c. with 20 µg of recombinant protein emulsified in complete Freund's adjuvant (Sigma) on day 1. Three weeks later (day 21), the mice were given a boosting injection with 10 µg of recombinant protein emulsified in incomplete Freund's adjuvant. A control group was included in each experiment that consisted of mice injected on days 1 and 21 with PBS and adjuvant alone. Blood samples were drawn from control and immunized mice on day 41, and sera were examined for antigen-specific antibody response (Durant et al., 2007).
• Persistence: Not noted.
• Immune Response: More than half of the protective antigens were related to iron metabolism. This observation could be explained by the model of infection that was used to screen for vaccine candidates. Because the infectious model is a rapid dissemination of the bacteria from the peritoneal site in 24 h, resulting in the killing of the host in less than 48 h, the antibodies which recognize the essential factors for bacterial survival and multiplication in the peritoneum and the blood will be the most effective (Durant et al., 2007).
• Side Effects: Not noted.
• Challenge Protocol: Control and immunized groups of mice were challenged on day 42 by i.p. injection of E. coli S26 at a dose that caused death in 50% of the mouse population (LD50) (5 x 105 CFU/mouse). The survival of mice was monitored for 2 days after challenge. The survival rate in the vaccinated group was compared to the one obtained in the control group (Durant et al., 2007).
• Efficacy: The number of mice surviving the lethal challenge was increased by 32% in the case of C0393 (Durant et al., 2007).
• Description: The high identity between Hbp and C0393 (78%) suggests that the C0393 protein may act as a hemoglobin protease with heme-binding properties. In addition to the role of the Hbp in the pathogenesis of extraintestinal E. coli strains, the protein has been shown to protect mice against the formation of abscesses following a challenge with E. coli and B. fragilis (Durant et al., 2007).