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When replicating its (+)ssRNA genome, the poliovirus RdRp is able to carry out recombination. Recombination appears to occur by a copy choice mechanism in which the RdRp switches (+)ssRNA templates during negative strand synthesis. [29] Recombination frequency is determined in part by the fidelity of RdRp replication. [30]
Negative-strand RNA viruses (−ssRNA viruses) are a group of related viruses that have negative-sense, single-stranded genomes made of ribonucleic acid (RNA). They have genomes that act as complementary strands from which messenger RNA (mRNA) is synthesized by the viral enzyme RNA-dependent RNA polymerase (RdRp).
Riboviria contains three types of viruses that replicate via RdRp: single-stranded RNA (ssRNA) viruses, which are either positive (+) or negative (-) sense, and double-stranded RNA viruses (dsRNA), all of which belong to the kingdom Orthornavirae. +ssRNA viruses have genomes that can functionally act as mRNA, and a negative-sense strand can ...
Positive-strand RNA viruses (+ssRNA viruses) are a group of related viruses that have positive-sense, single-stranded genomes made of ribonucleic acid. The positive-sense genome can act as messenger RNA (mRNA) and can be directly translated into viral proteins by the host cell's ribosomes .
For many -ssRNA viruses, at the end of transcription, RdRp stutters on a uracil in the genome, synthesizing hundreds of adenines in a row as part of creating a polyadenylated tail for the mRNA. [11] Some -ssRNA viruses are essentially ambisense, and have proteins encoded by both the positive and negative strand, so mRNA is synthesized directly ...
Negative-sense ssRNA viruses (Group V) must have their genome copied by an RNA replicase to form positive-sense RNA. This means that the virus must bring along with it the enzyme RNA replicase. The positive-sense RNA molecule then acts as viral mRNA, which is translated into proteins by the host ribosomes.
Nonsegmented -ssRNA viruses replicate in the cytoplasm, and segmented -ssRNA viruses replicate in the nucleus. During transcription, the RdRp produces one monocistronic mRNA strand from each segment of the genome. [3] [23] [37] All -ssRNA viruses are classified in the phylum Negarnaviricota in the kingdom Orthornavirae in the realm Riboviria.
Double-stranded RNA viruses (dsRNA viruses) are a polyphyletic group of viruses that have double-stranded genomes made of ribonucleic acid.The double-stranded genome is used as a template by the viral RNA-dependent RNA polymerase (RdRp) to transcribe a positive-strand RNA functioning as messenger RNA (mRNA) for the host cell's ribosomes, which translate it into viral proteins.