Characterization and structural localization of the reovirus lambda 3 protein

The putative reovirus RNA polymerase, protein lambda 3, was characterized using antiserum prepared against a TrpE-lambda 3 fusion protein synthesized in Escherichia coli. Immunofluorescence microscopy showed that lambda 3 accumulated in perinuclear inclusion bodies in reovirus-infected cells. Analysis of lambda 3 accumulation in infected cells indicates that, once synthesized, lambda 3 is quite stable throughout the course of infection. Anti-lambda 3 serum did not immunoprecipitate virions, core particles or iodinated surface proteins of either virions or cores. These results indicate that lambda 3 is located in the inner part of the core. Experiments involving urea denaturation of purified reovirus cores indicate that lambda 3 cannot be selectively removed from the core without total denaturation of the core structure. When the dsRNA genome was eliminated from the core, lambda 3 remained associated with the other viral proteins in the core. Thus, lambda 3 appears to be a stable, structural component of the reovirus core, not bound to genomic dsRNA or free in soluble form inside the core.