Rhabdovirus genome – Negative-sense RNA (- RNA)

A 19-year-old man is bitten by a wild dog in India. He becomes irritable, starts drooling and has a seizure. He is thought to have rabies.

This rhabdovirus produces protein by starting with a single strand of RNA using RNA polymerase to synthesise a complementary RNA strand. The newly-synthesised strand then acts as messenger-RNA (mRNA).

Choose the one answer which best describes the rhabdovirus genome.

Negative-sense RNA (- RNA) best describes the rhabdovirus genome.

Information on Rhabdovirus genome :

Viruses are classified by their genome. They can contain DNA or RNA. They can have a single or double strand of RNA or DNA.

The aim of this question is not to see whether candidates have memorised the genome of rhabdovirus. The description tells us that the virus contains a single strand of RNA initially, thus the first, second and last answer options cannot be correct.

If the strand of RNA was used directly as mRNA it would be positive-sense RNA. Examples include: picornavirus, flavivirus, coronavirus, and calicivirus.

We are told however that the strand needs to be copied by RNA polymerase to generate a complementary strand of RNA which then acts as mRNA. This is the definition of negative-sense RNA.

Further Reading:

Simplifying virus classification: The Baltimore system

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