IDENTIFICATION AND CHARACTERIZATION OF RNA-BINDING ACTIVITIES OF AVIAN REOVIRUS NONSTRUCTURAL PROTEIN SIGMA-NS

Cytoplasmic extracts prepared from avian reovirus (ARV) strain S1133-i nfected chicken embryo fibroblasts were examined for the presence of R NA-binding proteins in order to identify and characterize ARV RNA-bind ing proteins. Analysis of binding activity to poly(A)Sepharose indicat ed that infected cells contained significant amounts of a protein that co-migrated with ARV protein sigma NS present in total virus-infected cell extracts. Determination of the N-terminal amino acid sequence of several peptide fragments generated by V8 protease digestion of the p oly(A)-Sepharose-purified protein confirmed that this viral protein wa s sigma NS. Competition assays showed that single-stranded RNA from th e unrelated avian pathogen infectious bursal disease virus was able to compete for binding of sigma NS to poly(A)-Sepharose. These data sugg est that ARV sigma NS binds to single-stranded RNA in a nucleotide seq uence non-specific manner and is functionally similar to its counterpa rt specified by mammalian reovirus.