Investigating non-canonical programmed ribosomal frameshifting in porcine reproductive and respiratory syndrome virus (360G-Wellcome-203864_Z_16_A)

RNA viruses are under selection pressure to maintain a small genome, however they still need to produce a variety of proteins. To overcome these conflicting pressures, many viruses use non-canonical methods of translation control. One example of this is programmed ribosomal frameshifting (PRF), in which a percentage of ribosomes, while translating a ‘slippery sequence’ slip one or two nucleotides out of frame, consequently translating the remainder of the mRNA in a different reading frame and allowing expression of more than one protein from a single gene. This is normally stimulated by a downstream secondary RNA structure, however there are two known examples of a trans-acting viral protein being used as the stimulatory element. One example is found in the genome of porcine reproductive and respiratory syndrome virus (PRRSV): an Arterivirus that infects pigs, causing an estimated annual cost to the US swine industry of $664m. I will use structural techniques such as X-ray crystallography to derive information about the RNA/protein complex, and will investigate the efficiency and mechanism of this non-canonical PRF using ribosomal profiling in parallel with RNASeq. The latter will also allow me to analyse host and viral gene expression, to examine host-virus interactions in this important pathogen.