Host - virus interactions are greatly affected by the exceptionally rapid rate of virus evolution. Evolution of viruses is frequently driven by genetic recombination, a process that allows viruses to overcome immunity, to infect new host species and change disease symptoms in all types of living organisms. Virus recombination is also a major factor in emergence of new viruses, which is a continuing threat to our society. Therefore, studies on the effect of the host on the viral recombination process are critical to unravel virus evolution, which is currently poorly understood. This project focuses on a recently discovered key host factor affecting RNA recombination in Tomato bushy stunt virus. The host factor is Pmr1p Ca2+/Mn2+ ion-pump, which is a ubiquitous and conserved protein playing critical roles in human genetic diseases, such as Hailey-Hailey Disease and Darier Disease. In order to characterize the role of Pmr1p in viral RNA recombination, the investigator will use advanced genetics tools available for plant and yeast, which is a model host, in combination with biochemical approaches. This research is expected to lead to important new discoveries in viral recombination and contribute key knowledge to the role of the host in virus evolution and virus-host interactions. Broader impact: The research holds promise of benefiting society by leading to groundbreaking results in the area of virus recombination/evolution, host-virus interaction and the emergence of new viruses. The major limitation of current antiviral methods is that they could quickly become ineffective due to rapid virus evolution. Better understanding of viral RNA recombination will have tremendous impact on our abilities to develop better, longer lasting antiviral strategies. Education component: High school and undergraduate students will actively participate in research in the investigator's laboratory.
Intellectual merit: The emergence of new viruses is a major threat to our society. Newly emerged viruses or virus strains are frequently causing major diseases in humans and agriculture, break drug-resistance or immunity induced by vaccination. They are threat not only to human health, but to agriculture and the environment and natural resources in the land or the sea. How are these new viruses and strains formed? RNA recombination is a major factor driving virus evolution helping the emergence of new viruses or new strains. However, the role of the host in this process is unknown. This work by the PI has led to the discovery for the first time that a cellular enzyme plays a critical role in RNA virus recombination. The PI has shown that inactivation of the cellular Ca2+/Mn2+ ion pump increases viral recombination in model yeast host (that is easy to manipulate for this research) and in plants. This cellular ion pump, which is present in humans, animals and plants, is likely to affect other cellular processes as well, including possibly cancer and aging. The PI's group has also identified a key role for additional cellular enzymes in virus recombination. Namely, they have identified exoribonucleases (which cleave and degrade cellular and viral nucleic acids) with key functions in SUPPRESSING viral RNA recombination. However, other types of nucleases, called endoribonucleases, are shown by the PI's group to ENHANCE viral RNA recombination. Thus, cellular proteins have complex roles in formation of new viral recombinants. In this work, the PI’s group has unraveled the combined effects of environmental and host factors on the emergence of new recombinants. This discovery should invite the attention towards environmental factors, such as metal ion contaminations, in viral recombination. These groundbreaking discoveries should help researchers to better understand viruses, and how to defend ourselves, agriculture production and natural resources against dangerous viruses. These findings should also help to exploit benign viruses for the benefit of the society, including for vaccine production or in biotechnology. Broad impact: With the help of this grant, the PI has trained and mentored young scientists, including 2 postdocs, 2 graduate students, 5 undergraduate students, and 5 high school students. The PI's group has presented research results as invited talks, poster presentations and keynote presentations on the topic at departmental seminars, international and national meetings. The postdocs and senior graduate students were involved in mentoring activities with junior graduate students, undergraduate students, and high school students. They were also involved in teaching preparing them for future highly skilled activities in the society. The PI's group has disseminated the research findings in many peer-reviewed research articles and review papers on the topic. The high school students participating in research in the PI's lab presented talks at local high school research fairs (Dunbar Highschool, Lexington, KY). Two of the high school students won awards and presented their data at the international INTEL science fair (Los Angeles, CA) and presented research posters at AAAS annual meeting (Washington DC). The work has resulted in new datasets for viral recombination "hotspots" and provided new insights for teaching the key factors in the emergence of new viruses and the combined effect of viral, host and environmental factors in this process.
