Seven infection-specific polypeptides in BHK cells infected with Bunyamwera virus

Virus-specific polypeptide synthesis was examined in BHK cells and Vero cells infected with Bunyamwera virus. In BHK cells, in addition to the four previously reported virus-coded proteins (L, G1, G2, and N), three other infection-specific proteins were detected. These proteins, of nominal molecular weight 50,000 (p50), 16,000 (p16), and 13,000 (p13), were not labeled in mock-infected cells, were first synthesized between 4 and 8 h after infection, and were relatively prominent among the limited number of proteins generated late in infection. In preparations of purified Bunyamwera virus from BHK cell supernatants, p16 was detected but not p50 or p13. In Vero cells infected with Bunyamwera virus, both p50 and p13 were labeled strongly. Maprik virus, a member of the Mapputta group of arboviruses, is a member of the Bunyavirus genus (S.E. Newton, unpublished data). Maprik virus did not induce the synthesis of p50, p16, or p13; however, two smaller proteins (p17 and p15) which may correspond to p16 and p13 were labeled late in Maprik infection. Our data argue that p16 is a virus-coded component of the Bunyamwera virus particle and that p50 and p13 are virus-coded, nonstructural proteins.