Virus Replication

Understanding the molecular events accompanying virus replication is essential for the proper understanding and control of all virus diseases. The virus replication cycle generates new viral genomes and proteins in sufficient quantities to ensure propagation of the viral genome; this requires that the extracellular viral genome is protected from enzymatic degradation and can be introduced into further target cells for further rounds of replication. The initial recognition between virus and host is more complex than originally supposed and may involve more than one cellular receptor. A critical first intracellular step is the generation of viral mRNA by one of a limited number of strategies first described by David Baltimore. Lacking ribosomes, viruses have no means of producing protein and are reliant on the host cell for protein synthesis. Viral proteins are often modified by host cell glycosylation during or after virus assembly. Temporal regulation of intracellular events is critical in all but the very simplest of viruses, and some form of suppression of the host innate immune response is common to nearly all human viruses. Infected cells often produce non-infectious particles with incomplete genomes, and these defective interfering particles may play a role in pathogenesis. Understanding these processes will open up a range of targets for the development of novel therapies.