CHARACTERIZATION OF RUBELLA-VIRUS REPLICATION COMPLEXES USING ANTIBODIES TO DOUBLE-STRANDED-RNA

A feature of the rubella virus (RV) replication cycle is the formation of cytoplasmic vesicle-containing structures known as replication com plexes. Following detergent treatment of RV-infected cells, pre-embedd ing immunogold labeling electron microscopy using antiserum to double- stranded (ds) RNA was employed to characterize the replication complex es. Concentrations of gold particles were found associated with amorph ous material located within the RV replication complex. Unlabeled long fine strands, 3-5 nm in width, were also frequently seen associated w ith this gold-labeled material. On some occasions gold-labeled vesicle s within the replication complexes were also detected. The gold-labele d amorphous material was first detected in RV replication complexes at 12 hr postinfection, soon after the reported latent period of 8 hr. C oncentrations of gold particles were not detected in mock-infected cel ls. The findings in this study indicate that the amorphous material is released from detergent-disrupted vesicles within the replication com plex and that the vesicles contain the dsRNA. When cells were infected with the related semliki Forest virus (SFV) and examined using the sa me antibody, similar gold-labeled material associated with unlabeled f ine strands was also observed in SFV replication complexes. For both R V and SFV, the vesicles which line the inner membrane of the replicati on complexes contain the dsRNA which represent the viral replicative f orms and replicative intermediates. (C) 1994 Academic Press, Inc.