The interactions of host cell proteins with mouse hepatitis virus RNA

The involvement of host cell proteins in the transcription, replication and translation of mouse hepatitis virus is drawing more and more attention. New concepts such as transcriptional regulators in the RNA-dependent RNA synthesis have been established (Lai, 1998) and possible candidates from the host cell have been investigated. In this dissertation, emphasis has been laid on the 3′-untranslated region (3′-UTR) of the MHV genome and its complementary sequence which contain important regulatory regions that affect the viral subgenomic mRNA synthesis, replication and translation.; Here, I describe that polypyrimidine-tract binding protein (PTB) interacts specifically with the complementary strand of the MHV 3′-UTR (c3′-UTR) and that hnRNP A1 is the host cellular factor that interacts specifically with the MHV 3′-UTR. The binding sites of hnRNP A1 and PTB are complementary on opposite strands. The binding of PTB to MHV c3′-UTR also induces conformational changes in the viral RNA. Functionally, these RNA-protein interactions, together with the protein-protein interactions between these RNA-binding proteins, could induce potential 5′–3′ crosstalk between viral RNA ends and might influence the viral mRNA synthesis and translation. The involvement of PTB in the MHV replication cycle has also been investigated by overexpressing full-length and truncated mutants of PTB.