title: Localization and characterization of Sendai virus nonstructural C and C' proteins by antibodies against synthetic peptides.
abstract: Antibodies were raised in rabbits against two synthetic peptides, each 30 residues in length, one corresponding to the predicted common carboxyl termini of the nonstructural C and C' proteins of Sendai virus and the other to the unique amino terminus of the larger C protein. Each peptide was inoculated as a covalent complex with tetanus toxoid or in uncomplexed form. Only antibodies to the free carboxyl-terminal peptide precipitated both C and C' proteins made by in vitro translation of viral mRNA and reacted with the C protein from infected cells. These results confirm that the C and C' proteins are carboxyl-coterminal. Contrasting with the reported colocalization of intracellular measles virus C proteins with nucleocapsid inclusions, immunofluorescence studies revealed that Sendai virus C proteins were uniformly distributed in the cytoplasm whereas the viral P protein was present in inclusions that were mainly perinuclear. Since almost all P protein molecules are associated with viral nucleocapsids, these observations suggested that Sendai virus C protein molecules may be both nucleocapsid-associated and free in the cytoplasm. This interpretation was supported when the C and C' proteins were found in both nucleocapsid and free protein fractions of cell lysates. Anti-C antibodies did not inhibit viral RNA synthesis when added to an extract of infected cells. This result was consistent with the conclusion that the C proteins have no direct role in viral transcription, since virions lack C proteins but are transcriptionally active. Therefore, the functions of the C proteins remain undefined.
mesh_terms: D000818:Animals; D000911:Antibodies, Monoclonal; D002213:Capsid / Q000032:analysis; D002460:Cell Line; D004591:Electrophoresis, Polyacrylamide Gel; D004797:Enzyme-Linked Immunosorbent Assay; D005455:Fluorescent Antibody Technique; D007158:Immunologic Techniques; D010222:Parainfluenza Virus 1, Human / Q000032:analysis* / Q000235:genetics; D010455:Peptides / Q000138:chemical synthesis / Q000276:immunology; D012367:RNA, Viral / Q000096:biosynthesis; D011817:Rabbits; D014758:Viral Core Proteins / Q000032:analysis; D014764:Viral Proteins / Q000032:analysis* / Q000276:immunology
chemical_list: D000911:Antibodies, Monoclonal; D010455:Peptides; D012367:RNA, Viral; D014758:Viral Core Proteins; D014764:Viral Proteins; C051221:nonstructural C protein, Sendai virus