Professor and virologist Marilyn J. Roossinck describes her work and interesting elements of virus behavior. She tells listeners  Why plant viruses became the focus of her research, What she’s learned about the host impact on virus diversity, and How her work on persistent plant viruses has changed how she conceives of the larger virus community. Marilyn J. Roossinck, Ph.D. is a professor in plant pathology and environmental microbiology and biology. She’s at the Center for Infectious Disease Dynamics at the Huck Institute of Life Sciences at Pennsylvania State University. She describes for listeners how she first became interested in the field of virology and where that interest took her. Because viruses evolve rapidly, they can be a helpful vehicle for observing evolutionary processes. One of her early studies involved watching virus mutations of RNA viruses, noting the diversity of their populations. She then describes the work she’s done with the cucumber mosaic virus. Because the virus infects about 1,200 different species, they could compare virus evolution by starting with clones of the cucumber mosaic virus and see how the exact same virus progressed differently among host plants. Contrary to general thought, they found the virus behavior and diversity was dependent on the host plant.  She discusses some other studies including on a virus that has coevolved with the jalapeno and other pepper plants and what that plant virus accomplishes for that plant. She also talks about her work on a virus found in fungi that inhabit geothermal soil and viruses in Costa Rican plants. She explains how this work has caused her to think of viruses differently, as beneficial for the most part. In fact, she says pathogenic viruses are actually quite rare.  For more about her work, see roossincklab.com.