The molecular biology of coronavirus replication will be examinined using mouse hepatitis virus (MHV) as a model system. It has been shown that MHV infection induces the synthesis of two separate RNA dependent RNA polymerase activities. The proteins responsible for these activities will be identified by preparing specific antisera raised by immunization with either ppol-B-gel fusion proteins or synthetic peptides derived from both the 5' and 3' ends of the polymerase. These antisera will be used to inhibit polymerase activity, identify the proteins, and in conjunction with cross-linking reagents determine the presence of the nonstructural proteins in the polymerase complex. It has also been found that the nucleocapsid proteins binds specifically to genomic RNA and the subgenomic mRNAs. The RNA sequence that initiate this interaction will be determined. Finally, the maturational pathway of the virions will be studied by defining the interactions between the nucleocapsid and matrix protein. Recent interest in this group of viruses is based on the fundings that they have very unusual molecular structures and an unique mode of replication. They are a group of enveloped helical RNA viruses which have characteristic petal shaped clubs on their surface much like the influenza virus. The genomic RNA of this virus is considerably larger than any stable RNA known to exist in nature. The subgenomic mRNAs of coronaviruses are synthesized by a unique mechanism of discontinuous transcription, i.e. a leader RNA-primed transcription.
