Molecular Virology of Plant RNA viruses
We use Tombusviruses, small model RNA viruses of plants, to identify the viral and host players in replication and to unravel the mechanism of virus replication. RNA replication (multiplication) is the central process in virus infections, which in case of Tombusviruses is a robust process, and it leads to the production of millions of progeny viruses in a day per infected cells. Better understanding of virus replication is expected to lead to improved antiviral strategies and enhanced resistance against virus diseases in plants. The basic discoveries made with Tombusviruses are expected to influence studies on replication of important human and animal pathogens.
The second area of major emphasis in my research program is to understand the mechanism of virus evolution. This area is also important since viruses can change dramatically via recombination, which, in turn, can lead to emergence of new viruses and strains. The new recombinant viruses may elude host defenses initially due to their unique features. RNA recombination in viruses can also hinder the use of viruses as gene delivery systems or gene expression vectors. We are working on the dissection of the mechanism of RNA recombination, which may lead to development of recombination predicting software, safer virus vectors and lead to improved vaccination programs.
RECENT IMPACTS OF OUR RESEARCH (last three years)
We have a vigorous research program that focuses on Tombusvirus replication and recombination, two of the most important basic processes in plant and general virology.
We have developed an in vitro Tombusvirus replication assay based on partially-purified replicase from plants. This is a major advance in Tombusvirus research by allowing biochemical characterization of the roles of RNA elements and protein factors in replication.
We have also developed an in vitro replication assay for Carmoviruses based on E. coli -expressed and purified replicase proteins. Therefore, we are in a unique situation to study virus replication in the absence of host factors. In addition, this assay allows the efficient and economical testing of antiviral compounds.
We have characterized RNA elements (viral promoters and replication enhancers) that play important roles in virus replication. We have also discovered a novel replication silencer, which down regulates viral RNA replication. This element is an essential regulatory element.
We have developed YEAST as a model host for replication of a model tombusvirus replicon. Yeast will facilitate studies on host factors that are important in virus replication.
We have studied biochemical features of the viral replicase proteins, including RNA-binding and protein interaction.
We have developed in vivo and in vitro RNA recombination systems based on the Tombusvirus and the Carmovirus replicase preparations. This will help us dissect the mechanism of RNA recombination.