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Created page with " = Viral replication = '''Viral replication''' is the formation of biological [https://en.wikipedia.org/wiki/Virus viruses] during the infection process in the..."
= Viral replication =
'''Viral replication''' is the formation of biological [https://en.wikipedia.org/wiki/Virus viruses] during the infection process in the target host cells. Viruses must first get into the cell before viral replication can occur. Through the generation of abundant copies of its [https://en.wikipedia.org/wiki/Genome genome] and packaging these copies, the virus continues infecting new hosts. Replication between viruses is greatly varied and depends on the type of genes involved in them. Most DNA viruses assemble in the nucleus while most RNA viruses develop solely in cytoplasm.
=== Single-stranded RNA viruses ===
==== positive-sense ====
The positive-sense RNA viruses and indeed all genes defined as '''[https://en.wikipedia.org/wiki/Positive-sense positive-sense]''' can be directly accessed by host ribosomes to immediately form proteins. These can be divided into two groups, both of which replicate in the cytoplasm:
*Viruses with [https://en.wikipedia.org/wiki/Polycistronic polycistronic] [https://en.wikipedia.org/wiki/MRNA mRNA] where the genome RNA forms the mRNA and is translated into a [https://en.wikipedia.org/wiki/Polyprotein polyprotein] product that is subsequently cleaved to form the mature proteins. This means that the gene can utilize a few methods in which to produce proteins from the same strand of RNA, reducing the size of its genome.
*Viruses with complex transcription, for which [https://en.wikipedia.org/wiki/Subgenomic subgenomic] mRNAs, [https://en.wikipedia.org/wiki/Ribosomal_frameshifting ribosomal frameshifting] and [https://en.wikipedia.org/wiki/Proteolytic proteolytic] processing of polyproteins may be used. All of which are different mechanisms with which to produce proteins from the same strand of RNA.
==== negative-sense ====
The negative-sense RNA viruses and indeed all genes defined as '''[https://en.wikipedia.org/wiki/Negative-sense negative-sense]''' cannot be directly accessed by host ribosomes to immediately form proteins. Instead, they must be [https://en.wikipedia.org/wiki/Transcription_(genetics) transcribed] by viral polymerases into the "readable" complementary positive-sense. These can also be divided into two groups:
*Viruses containing nonsegmented [https://en.wikipedia.org/wiki/Genomes genomes] for which the first step in replication is transcription from the negative-stranded genome by the viral RNA-dependent RNA polymerase to yield monocistronic mRNAs that code for the various viral proteins. A positive-sense genome copy that serves as template for production of the negative-strand genome is then produced. Replication is within the cytoplasm.
*Viruses with segmented genomes for which replication occurs in the cytoplasm and for which the viral RNA-dependent RNA polymerase produces monocistronic mRNAs from each genome segment.
