“Extraintestinal pathogenic Escherichia coli (ExPEC) is an important pathogen that can cause systemic infections in a broad spectrum of mammals and birds. To date, commercial vaccines CX-5461 mouse against ExPEC infections in pigs are rare and antibiotic resistance has become a serious clinical problem. Identification of protective
antigens is helpful for developing potentially effective vaccines. In this study, two outer membrane porins, OmpC and OmpF, of porcine ExPEC were cloned and expressed to investigate their immunogenicity. Intraperitoneal immunization of mice with the purified recombinant proteins OmpC and OmpF stimulated strong immunoglobulin G (IgG) antibody responses. Both IgG1 and IgG2a subclasses were induced, with a predominance of IgG1 production. After challenge with 2.5 × 107 CFU (5 × LD50) of the highly virulent ExPEC strain PCN033, 62.5% and 87.5% protection was observed in mice immunized with OmpC and OmpF, respectively. In addition,
both anti-OmpC and anti-OmpF sera can mediate complement-dependent opsonophagocytosis. Phylogenetic analysis showed that the ompC gene was ubiquitously present in all E. coli strains, whereas the ompF gene was mutated in certain strains. Furthermore, the selection analysis indicated that gene ompC may be subject to strong immune pressure. Our results demonstrated that OmpC is a promising vaccine target against ExPEC infections in swine. Pathogenic Escherichia coli is an important zoonotic etiological agent that can infect a broad spectrum of mammals and birds. Pathogenic E. coli Panobinostat in vivo can be divided into two classes: intestinal and extraintestinal pathogenic E. coli (ExPEC) strains (Russo & Johnson, 2000). ExPEC strains possess certain specific virulence traits that enable them to invade
and colonize extraintestinal sites and cause a wide range of infections, such as urinary tract infections, meningitis, pneumonia, osteomyelitis, and surgical site infections (Orskov & Orskov, 1985). Recent reports show that ExPEC has been isolated frequently from clinical samples in the pig industry in China (Tan et al., 2012). However, to date, the Digestive enzyme damage caused by ExPEC infections in swine has not been paid sufficient attention. The two common approaches for prevention and therapy of bacterial diseases are vaccination and antibiotic therapy. Our recent study has demonstrated that antibiotic resistance is ubiquitously present in the porcine ExPEC strains isolated in China; 95.2% of which carried resistance to at least five antibiotics, and 60.3% were resistant to > 10 antimicrobials (Tang et al., 2011). Therefore, antibiotic treatment against ExPEC infections in pigs is limited. In addition, Tan et al. (2012) have reported that ExPEC infections are epidemic in China and have become a potential public health threat. It is desirable to find potential vaccine candidates to prevent this serious swine disease.