|Rooney, Alejandro - Alex|
Submitted to: Genetics
Publication Type: Peer reviewed journal
Publication Acceptance Date: 2/3/2006
Publication Date: 4/15/2006
Citation: Rooney, A.P., Friedman, R., Hecht, D.W., Maddox, C.W. 2006. Analysis of core housekeeping and virulence genes reveals cryptic lineages of Clostridium perfringens that are associated with distinct disease presentations. Genetics. 17:2081-2092. Interpretive Summary: This manuscript describes work on the genetic diversity of Clostridium perfringens, an important human and domestic animal bacterial pathogen that causes food poisoning, gastrointestinal necrosis, or gangrene. The current line of thinking regarding the diversity of C. perfringens is that it is a single evolutionary lineage. However, our research shows that it is actually composed of 5 distinct lineages that differ genetically as well as in the type of disease that they cause. Our findings carry important ramifications for the diagnosis of C. perfringens disease and for efforts aimed at C. perfringens disease surveillance and source-tracking.
Technical Abstract: Clostridium perfringens is an important human and animal pathogen that causes a number of different diseases that vary in their etiology and severity. Currently, the identification of C. perfringens strains is based solely upon the presence and absence of particular toxin genes. Unfortunately, this method of identification is not complete. In this study, we examined the nucleotide polymorphism and constructed phylogenies of a sample of genes from 248 C. perfringens strains. Our goal was to further understand the differences in virulence among strains. We found that purifying selection and recombination play central roles in shaping the patterns of nucleotide substitution and polymorphism in both housekeeping and virulence genes. However, the relative effects of recombination and natural selection varied, indicating that the core genome does not evolve homogeneously. Also, despite detecting a high frequency of recombination across the C. perfringens genome, five distinct evolutionary lineages were detected. These lineages reflect distinct ecologies and represent the incipient stages of speciation among C. perfringens strains. Their discovery carries important implications for human and veterinary disease epidemiology and provides important insights into the pathways through which virulence has evolved in this organism.