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Rotavirus. A nucleic acid test (NAT) is a technique used to detect a particular nucleic acid sequence and thus usually to detect and identify a particular species or subspecies of organism, often a virus or bacterium that acts as a pathogen in blood, tissue, urine, etc. NATs differ from other tests in that they detect genetic materials (RNA or DNA) rather than antigens or antibodies.
In the past nucleic acid tests have mainly been used as a secondary test to confirm positive serological results. [3] However, as they become cheaper and more automated, they are increasingly becoming the primary tool for diagnostics and can also be use for monitoring of treatment of viral infected individuals t.
The US CDC's COVID-19 laboratory test kit. COVID-19 testing involves analyzing samples to assess the current or past presence of SARS-CoV-2, the virus that cases COVID-19 and is responsible for the COVID-19 pandemic. The two main types of tests detect either the presence of the virus or antibodies produced in response to infection.
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 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.
Inside the envelope, there is the nucleocapsid, which is formed from multiple copies of the nucleocapsid (N) protein, which are bound to the positive-sense single-stranded RNA genome in a continuous beads-on-a-string type conformation. [49] [56] N protein is a phosphoprotein of 43 to 50 kDa in size, and is divided into three conserved domains.
The SARS-related coronavirus is an enveloped, positive-sense, single-stranded RNA virus. Its genome is about 30 kb, which is one of the largest among RNA viruses. The virus has 14 open reading frames which overlap in some cases. [19] The genome has the usual 5′ methylated cap and a 3′ polyadenylated tail. [20]
Double-stranded RNA viruses (Group III) contain from one to a dozen different RNA molecules, each coding for one or more viral proteins. Positive-sense ssRNA viruses (Group IV) have their genome directly utilized as mRNA, with host ribosomes translating it into a single protein that is modified by host and viral proteins to form the various ...