Bunyavirus Nucleoprotein, N, and a Non-structural Protein, NSS, Are Coded by Overlapping Reading Frames in the S RNA

Department of Microbiology, The Medical Center, University of Alabama in Birmingham, Birmingham, Alabama 35294, U.S.A. It has been shown previously, by sequence analysis of the S RNA segment of snowshoe hare (SSH) bunyavirus, that two overlapping open reading frames in the viral complementary sequence code for proteins with molecular weights of 26.8 x 10 3 and 10.5 x 10 3 respectively. In addition to the viral nucleocapsid (N) protein, which is coded by the S RNA, analyses of parental and reassortant bunyavirus-infected cell extracts have shown that the viral S RNA and M RNA species each code for nonstructural proteins (NS S and NS M , respectively). In the present report, in vitro translation analyses of the S mRNA species recovered from virus-infected cells indicate that a single size class of mRNA directs the synthesis of N and NS S . Compositional analyses of selected tryptic peptides of N and NS S have provided proof that N is the product of the first open reading frame, and NS S the product of the second. Keywords: snowshoe hare bunyavirus, bunyavirus mRNA coding assignments, La Crosse bunyavirus Received 10 March 1983; accepted 19 April 1983.