Viruses with positive-sense single stranded RNA genomes comprise the majority of viruses pathogenic to humans, animals and plants like Poliovirus, West Nile Virus, Equine arteritis virus, Cucumber Mosaic Virus and Brome Mosaic Virus. Brome Mosaic Virus (BMV) belongs to this group and is in the family Bromoviridae, it is the type member of the family. BMV is used as a model to study replication, packaging and recombination of positive-sense RNA viruses. It is a tripartite virus with three RNA molecules each is packaged independently. For a successful infection, all three particles must infect the same cell for efficient replication of the genome and packaging. Chapter one of this dissertation will focus on proteome analysis of Nicotiana benthamiana infected with BMV to study N. benthamiana proteome that interact with three virally encoded proteins: the replicase proteins p1a and p2a, and the coat protein. N. benthamiana is an experimental plant host that is widely used in research. For that Co-immunoprecipitation was performed to recovered host proteins that interact with the tested virally encoded proteins. Bioinformatics analyses to predict the subcellular localization and functions of the recovered proteins is discussed. Chapter two, similarly to chapter one, will focus on proteome analysis of the natural host for BMV Hordeum vulgare infected with BMV to study its proteome that interact with the three virally encoded proteins: p1a, p2a, and the coat protein. In Chapter three the effect of silencing one of the proteins that interact with BMV replicase protein on BMV accumulation will be examined. Specifically, the protein S-phase kinase related protein-1 was silenced via Virus Induced Gene Silencing (VIGS) and further infection with BMV to examine if SKP1 is important for BMV replication.