Sigma Xi - University of South Dakota Chapter

University of South Dakota Branch of Sigma Xi

Distinguished Lecturer

James Van Etten, PhD

William Allington Distinguished Professor of Plant Pathology

University of Nebraska, Lincoln

Giant Viruses Change the Perception of Viruses

A research paper appeared about a year ago in the Proc. Natl. Acad. Sci. USA entitled “Thirty-thousand-year-old distant relative of giant icosahedral DNA viruses with a pandoravirus morphology“, which generated a lot of public interest including being mentioned on CNN news and written about in the New York Times. One reason for the interest was that the virus had been frozen for at least 30,000 years and an infectious virus was recovered.  This general talk will focus on the relatively recent discovery of giant viruses (giruses) that have from 400 to 2500 protein encoding genes.  In contrast, HIV and influenza viruses encode about 12 genes and viruses that infect higher plants usually have even fewer genes.  To put these numbers into perspective, the smallest symbiotic bacterium has about 160 protein-encoding genes and the smallest bacterium that can be grown in culture has about 500 genes; the smallest symbiotic eukaryotic organism has less than 2000 genes.  Finally, we will finish up with a few comments on the question: will viruses that are a threat to animal and human health be uncovered in frozen permafrost regions as the climate warms?

Tuesday, April 1, 2015

Lee Med Room 105

2-3 PM

 James Van Etten is the William B. Allington Distinguished Professor of Plant Pathology at the University of Nebraska-Lincoln. Dr. Van Etten received his PhD in 1965 from the Department of Plant Pathology at the University of Illinois. After spending a year as a NSF postdoc in the Department of Genetics at the University of Pavia (Italy), he joined the UNL Plant Pathology Department. His early research at UNL focused on two topics, the biochemistry of fungi, primarily spore germination, and the characterization of the unusual bacteriophage phi6. For the last 30+ years, his research has focused on the isolation and characterization of large icosahedral, dsDNA-containing, plaque-forming viruses that infect certain unicellular, eukaryotic chlorella-like green algae. These viruses are ubiquitous in fresh water from all over the world. The chlorella viruses have genomes as large as 370 kb that contain as many as 400 protein encoding- and 16 tRNA encoding-genes.