The Importance of Virulence Prediction and Gene Networks in Microbial Risk Assessment

ABSTRACT

For microbial risk assessment, it is necessary to recognize and predict virulence of bacterial pathogens, including their ability to contaminate foods. Hazard characterization requires data on strain variability regarding virulence and survival during food processing. Moreover, information on virulence is important for qualitative or quantitative description of public health outcomes following infection. The quest to understand bacterial disease started with the isolation of bacterial pathogens and continued with elucidating the mechanisms of bacterial pathogenicity. Now the goal is to predict virulence genes from total genome sequences. The deterministic approach of considering gene function relating to an organism's pathogenicity has its limits. Gene function prediction based on sequence similarity is also not without flaws. Bioinformatic analysis can reveal virulence potential of a genome-sequenced strain. However, a gene's contribution to phenotype is determined by the context of other genes present in the genome and this should be considered. Quantitative effects of gene expression should also be taken into account. Thus, if the gene networks essential for bacterial pathogenesis are understood, we can better predict genes coding for virulence. It may even become possible to identify species that are not yet pathogenic, but have the correct genetic repertoire to become so if particular genes were acquired. Gene network identification may become an important component for identification and characterization of microbial hazards, including emerging pathogens, in the context of microbial risk assessment.

Keywords:

• virulence gene recognition
• gene networks
• pathogenicity
• emerging pathogens

ACKNOWLEDGMENTS

DWU is funded by grants from the Danish Research Foundation.

The views expressed are solely those of the authors and are not representative of policies or opinions of the U.S. Environmental Protection Agency.