Negative (−) single-strand RNA (−ssRNA)

Definition

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.

5 Must Know Facts For Your Next Test

1. −ssRNA viruses must carry their own RNA-dependent RNA polymerase enzyme because the host cell cannot perform this function.
2. The conversion of −ssRNA to +ssRNA occurs in the cytoplasm of the host cell.
3. Notable viruses with −ssRNA genomes include Influenza virus and Rabies virus.
4. 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.
5. Vaccines for some −ssRNA viruses, like Influenza, are designed to target specific viral proteins produced after the +ssRNA is synthesized.

Review Questions

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.