The researchers then screened a library of almost 1,000 Y. pestis mutants and found that six virulence factors are crucial for the bacterium to have full virulence. Of the six virulence factors, three are also required for infections in mammals. One of these factors is similar to an exported protein of Salmonella enterica. In a study http://www.dukemednews.org/news/article.php?id=7647 published last year, Abalallay showed that Salmonella uses similar virulence factors to infect both mammals and C. elegans.
"The protein produced by this new Y. pestis virulence-related gene belongs to a family of uncharacterized proteins found exclusively in pathogenic enterobacteria," Aballay said. "This work links for the first time this particular family of bacterial proteins to virulence and we have done so by using a C. elegans pathogenesis system and a new mouse model of plague."
Aballay said that these types of conserved virulence factors may regulate innate immunity in a broad variety of hosts, including C. elegans, fleas and mammals.
"The importance of our work is that it will permit us to use a model whose genetics can be easily manipulated as a viable alternative not only for the identification of novel Y. pestis virulence factors but also to study conserved innate immune responses to the bacterium," Aballay said. "This may help us in developing strategies to protect humans from the plague."
Since the KIM5 strain of Y. pestis is well characterized and has a lower biosafety ranking than other infectious or toxic agents, Aballay believes that it will much easier for research laboratories to conduct research on virulence and innate immunity.
Other members of the research team were Duke's Katie Styer, Gregory Hopkin
Source:Duke University Medical Center