Molecular characterization and expression of Salmonella enterica serotype Enteritidis fimbrial genes in Escherichia coli.

摘要

Salmonella enterica serotype Enteritidis (S . Enteritidis) is perceived as an expanding pandemic and a significant threat to the human health worldwide. Consequently, numerous efforts to determine sources of outbreaks and to control this pathogen in farms have been made. To facilitate epidemiological investigations, isolates of S. Enteritidis, obtained from outbreak and source farms, are compared using typing methods to identify sources of infection of human outbreaks. Currently, molecular typing methods used to assess strains of S. Enteritidis phage type (PT) 4 are not able to consistently demonstrate differences among strains from distinct outbreaks. To improve the accuracy of S. Enteritidis PT 4 characterization and epidemiological studies, a number of molecular typing methods were evaluated and compared in their ability to discriminate S. Enteritidis PT 4 isolates from different origins. Furthermore, due to the relevance of S. Enteritidis to food safety, several attempts have been made to control of S. Enteritidis infection in poultry. However, currently available live attenuated and killed vaccines against S. Enteritidis have shown limited reduction in the colonization of S. Enteritidis in internal organs, intestines and cecum, providing incomplete protection to birds. As a result, there is an urgent need for a successful vaccine to protect ensure S. Enteritidis-free food products and, thus, reduce foodborne illnesses associated with the consumption of contaminated eggs and poultry products. Two live recombinant vaccine strains based on the sefA and sefABCD fimbrial genes, respectively, were developed and the protection elicited by the strains was evaluated in chickens against S. Enteritidis infection.