This subproject is one of many research subprojects utilizing the resources provided by a Center grant funded by NIH/NCRR. The subproject and investigator (PI) may have received primary funding from another NIH source, and thus could be represented in other CRISP entries. The institution listed is for the Center, which is not necessarily the institution for the investigator. The Bovine Viral Diarrhea Virus, similarly to HCV, is a member of Flaviviridae, and within this category, it is a Pestivirus. Matt Paulson has identified a mutation site of the HCV NS4B homologue in BVDV which resulted in an increased resistance following the infection (the cells did not die after infection). We aim to first identify the cellular interacting partners of the normal and the mutant protein. We have compared several isolation methods and using magnetic beads so far we have identified one of the expected interacting partners.