HORIZONTAL GENE EXCHANGE AND GENOME EVOLUTION OF MYOVIRUSES IN AN AQUATIC ENVIRO

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This subproject is one of many research subprojects utilizing the resources provided by a Center grant funded by NIH/NCRR. The subproject and investigator (PI) may have received primary funding from another NIH source, and thus could be represented in other CRISP entries. The institution listed is for the Center, which is not necessarily the institution for the investigator. Bacteriophages are responsible for the virulence of many bacterial pathogens. Phage-encoded virulence factors include the shiga toxins in pathogenic strains of Escherichia coli, the cholera toxin in Vibrio cholerae, and the botulinum neurotoxins in Clostridium botulinum. Bacteriophages can drive the emergence and evolution of new pathogenic bacterial strains by the horizontal transfer of virulence factors and thus an understanding of bacteriophage genome evolution has important public health implications. This research project examines the genetic structure, dynamics, and evolution of bacteriophage genomes in an aquatic environment. We will test the hypothesis that much of the current bacteriophage diversity can be attributed to horizontal genetic exchange events that occurred recently. A natural community of aquatic bacteriophages in the Myoviridae family is being developed as a model system to address questions about bacteriophage genome evolution. Core-viral and host-derived genes are being sequenced from bacteriophages isolated over the past nine years as well as from new isolates obtained from Narragansett Bay. Bioinformatic tools are being used to analyze these sequences to: (1) construct phylogenetic gene and genome trees, (2) compare relative rates of divergence among genes, (3) detect and date horizontal gene transfer events, and (4) assess the number of possible genetic exchanges among phages and between phages and their hosts. The capability of these bacteriophages to carry excess genetic material derived from their hosts, other phages, or a common gene pool is being assessed using pulsed field gel electrophoresis. Undergraduate students participate in all aspects of the research. This pilot project is training undergraduate students both during the summer and the academic year in key molecular genetic techniques used in biomedical research. Students will gain experience in scientific communication, laboratory techniques, use of key instrumentation, and bioinformatics as they complete individual projects.