Equine infectious anemia virus is a retrovirus that encodes four accessory proteins in addition to three structural proteins. One of the accessory proteins, designated only as ‘S2’ is of unknown function. S2 has been shown to play an important role in viral replication and disease expression, however, specific functions of S2 are not known. As a first step to elucidate the function of S2, the protein was used as bait in a yeast two hybrid screen and was shown to interact with the cellular proteins TBP-1 and OS-9. My current studies probe the S2 amino acids important for interaction with OS-9. Three S2 mutants were designed with mutations generated in regions thought to be important for protein-protein interaction. These mutants were tested for interactions of S2 with OS-9 using a yeast two hybrid screen. None of the mutants significantly disrupted the interaction of S2 and OS-9, therefore it can be concluded that the three mutations created do not lie in areas of critical interaction of S2 and OS-9. Currently, an allele library containing random S2 mutants is being generated. These mutants will then be tested in a yeast two hybrid screen. Mutants that are shown to cause a disruption in S2/OS-9 interaction will then be sequenced to determine where the mutations occur
