Evaluation of a Yeast Expression System to Direct Assembly of the Drosophila melanogaster Nora virus. Kellie D. Licking-Murray, Brad L. Ericson, Darby J. Carlson, Kimberly A. Carlson. Biology, University of Nebraska at Kearney, Kearney, NE.

   Nora virus is a recently discovered RNA picorna-like virus that produces a persistent infection in Drosophila melanogaster. This virus is of interest because it is similar to the human picornaviruses that are responsible for human diseases, such as polio, hepatitis A, foot and mouth disease, and the common cold. The Nora virus RNA genome is approximately 12,000 bases long and is split up into four open reading frames (ORF1, -2, -3 and -4). ORF4 is most likely expressed as a polyprotein that is cleaved into three polypeptides by the viral-encoded protease, and these are designated as viral protein (VP) 4A, VP4B, and VP4C. These three viral proteins are thought to be the major capsid components of the virus, making ORF4 of particular interest in how this virus assembles. For this study, a yeast protein expression system was transformed and the genes from ORF1, -3, and -4 were cloned into the yeast system to express these genes of interest. Additionally, ORF1 and ORF3, and all three ORF4 proteins, were combined into one yeast clone to determine if virus-like particles can be assembled. The Nora virus assembly pathway is not yet known, but an understanding of this could lead to a deeper comprehension of how picornaviruses, in general, undergo assembly. This work was made possible by Grant Number P20GM103427 from the National Institute for General Medical Science, a component of the National Institutes of Health.