Negative single-strand RNA (−ssRNA) is a type of viral RNA that requires conversion to positive-sense RNA before it can be translated by host ribosomes. This conversion is carried out by an RNA-dependent RNA polymerase.
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−ssRNA viruses must carry their own RNA-dependent RNA polymerase enzyme because the host cell cannot perform this function.
The conversion of −ssRNA to +ssRNA occurs in the cytoplasm of the host cell.
Notable viruses with −ssRNA genomes include Influenza virus and Rabies virus.
The replication cycle of −ssRNA viruses typically involves the synthesis of a complementary positive strand that serves as a template for protein synthesis and new viral genomes.
Vaccines for some −ssRNA viruses, like Influenza, are designed to target specific viral proteins produced after the +ssRNA is synthesized.
Review Questions
Why do −ssRNA viruses need their own RNA-dependent RNA polymerase?
Where in the host cell does the conversion from −ssRNA to +ssRNA occur?
Name two notable viruses that have −ssRNA genomes.
Related terms
Positive-sense single-strand RNA (+ssRNA): +ssRNA can be directly translated by host ribosomes into viral proteins.
RNA-dependent RNA polymerase (RdRp): An enzyme used by RNA viruses to replicate their genomes.
Influenza Virus: A common example of an enveloped virus with a negative-sense single-strand RNA genome.
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