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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.
[3] [4] They are enveloped viruses with a positive-sense single-stranded RNA genome and a nucleocapsid of helical symmetry. [5] The genome size of coronaviruses ranges from approximately 26 to 32 kilobases , one of the largest among RNA viruses. [ 6 ]
The SARS-CoV-2 RNA sequence is approximately 30,000 bases in length, [110] relatively long for a coronavirus—which in turn carry the largest genomes among all RNA families. [111] Its genome consists nearly entirely of protein-coding sequences, a trait shared with other coronaviruses.
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. Retroviruses (Group VI) have a single-stranded RNA genome but, in general, are not considered RNA viruses because they use DNA intermediates to replicate.
Positive-strand RNA virus genomes usually contain relatively few genes, usually between three and ten, including an RNA-dependent RNA polymerase. [4] Coronaviruses have the largest known RNA genomes, between 27 and 32 kilobases in length, and likely possess replication proofreading mechanisms in the form of an exoribonuclease within nonstructural protein nsp14.
Double-stranded RNA (dsRNA) is RNA with two complementary strands found in cells. It is similar to DNA but with the replacement of thymine by uracil and the adding of one oxygen atom. [ 1 ] Despite the structural similarities, much less is known about dsRNA.
SARS-CoV-2 antigens can be detected before onset of COVID-19 symptoms (as soon as SARS-CoV-2 virus particles) with more rapid test results, but with less sensitivity than PCR tests for the virus. [57] COVID-19 rapid antigen tests are lateral flow immunoassays that detect the presence of a specific viral antigen, which indicates current viral ...
COVID-19 rapid antigen tests or RATs, also frequently called COVID-19 lateral flow tests or LFTs, are rapid antigen tests used to detect SARS-CoV-2 infection . They are quick to implement with minimal training, cost a fraction of other forms of COVID-19 testing , and give users a result within 5–30 minutes.