Self-amplifying RNA viruses are characterized by a single-stranded RNA (ssRNA) genome that is enclosed in a protein capsid and envelope structure. RNA viruses may carry positive or negative sense genomes, as seen in the case of alphaviruses and flaviviruses, or negative sense genomes as seen in the case of rhabdoviruses and measles viruses. However, genomes of RNA viruses can function in the cytoplasm without transporting nucleic acids to the nucleus. If the infecting newly introduced ssRNA genome has positive polarity, translation can start right away. While the production of a positive-strand RNA template is necessary for negative-sense RNA molecules. All self-amplifying viruses with RNA as a genome initiate the replication process by expressing their non-structural genes, which results in the generation of the RNA replicon, an RNA replication complex. The robust RNA replication that occurs within cells that are infected is caused by this complex. Strong sub-genomic promoters have been found to enable a single RNA molecule to produce approximately 200,000 copies of its own. This unique property has been used to create expression vectors from self-amplifying RNA viruses that have been used in primary cells, in-vivo research, and a variety of mammalian and non-mammalian cell lines.
Keywords: Self-replication, single-stranded RNA virus, vectors, in vivo research