Suttle, C.A. (submitted/invited) Genetic diversity in marine viral communities. Abstracts of the American Society of Limnology and Oceanography, Santa Fe, NM, February 1997.

Viruses are ubiquitous and abundant in marine ecosystems; yet, we only have cursory information on the genetic diversity of viruses in natural communities. We have used an approach of identifying regions within the DNA polymerase genes of viruses that are specific to particular viral groups. This information is then used to design PCR primers that can be employed to amplify viral DNA directly from natural samples, without the need for cultivating the viruses. These fragments can then be sequenced directly, or restriction digested, and compared with known viruses. Alternatively, viruses can be isolated for which there are hosts in culture, and clonal isolates of these viruses can be compared by sequence analysis or restriction fragment length polymorphism analysis. Using these approaches we have found that viruses infecting some hosts (e.g. the phytoplankter Micromonas pusilla) have a high degree of genetic diversity; whereas, viruses infecting other hosts (e.g. the bacterium Vibrio natriegens) are very similar. These results imply that there are fundamental differences among viral-host systems that affect the diversity of viral populations in nature.