RNA viruses are primarily classified based on the nature of their genetic material: whether it is double-stranded (dsRNA) or single-stranded (ssRNA). If single-stranded, they are further classified by the sense of the RNA.
Here's a breakdown:
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Double-Stranded RNA (dsRNA) Viruses: These viruses have a genome consisting of two strands of RNA. A well-known example is the Reovirus.
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Single-Stranded RNA (ssRNA) Viruses: These viruses possess a genome made up of a single RNA strand. They are further categorized based on the sense or polarity of the RNA.
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Positive-Sense RNA (+RNA) Viruses: The RNA genome is similar to mRNA and can be immediately translated into proteins by the host cell's ribosomes. Examples include Poliovirus and Hepatitis A virus. This type of RNA is "ready to go" for protein synthesis.
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Negative-Sense RNA (-RNA) Viruses: The RNA genome is complementary to mRNA and cannot be directly translated. It must first be transcribed into a positive-sense RNA molecule by an RNA-dependent RNA polymerase carried within the virus. Examples include Rabies virus and Influenza virus.
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In summary, the main categories are:
| Category | Description | Examples |
|---|---|---|
| dsRNA Viruses | Genome composed of double-stranded RNA | Reovirus |
| ssRNA (+ sense) Viruses | Genome is positive-sense, directly translatable RNA | Poliovirus, Hepatitis A Virus |
| ssRNA (- sense) Viruses | Genome is negative-sense, requires transcription | Rabies virus, Influenza Virus |
