Diversity of viruses as revealed by DNA polymerase gene sequence analysis.

Curtis Suttle and Steven Short

Departments of Earth and Ocean Sciences (Oceanography), Botany and Microbiology & Immunology, University of British Columbia.

Recent methodological developments have allowed the use of the polymerase chain reaction (PCR) to examine the diversity of algal virus isolates, and to infer taxonomic relationships among the isolates. DNA polymerase genes are highly conserved and are therefore suitable targets for PCR analysis of microbes that do not encode rRNA. As natural virus communities are largely made up of dsDNA viruses, and as many dsDNA algal viruses encode their own DNA polymerase, PCR primers can be designed to amplify fragments of these genes. This approach can also be used to examine the diversity of natural communities of viruses without the need for culture. This approach has been used to examine the genetic diversity in natural communities of viruses that infect phytoplankton. Algal-virus-specific primers were used to amplify polymerase fragments from natural virus samples, demonstrating the presence of a diverse community of viruses closely related to those that are known to infect phytoplankton. We have modified this approach by using denaturing gradient gel electrophoresis (DGGE) to rapidly analyze PCR products. DGGE will permit rapid and efficient fingerprinting of natural marine viral communities, and allow spatial and temporal differences in viral community structure to be examined.

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