Question

Morbilli viruses are a type of

• A. Single stranded, negative sense RNA viruses
• B. Single stranded, positive sense RNA viruses
• C. DNA viruses
• D. Double-stranded RNA virus

Hint:

All viruses belonging to the order Mononegavirales (such as Paramyxoviridae, Rhabdoviridae, and Filoviridae) possess non-segmented, single-stranded, negative-sense RNA genomes.

Answer 1

The Correct Option is A

Step 1: Understanding the Concept:
Viruses are classified based on their genome type, capsid symmetry, and presence of an envelope.
The genus Morbillivirus belongs to the family Paramyxoviridae, within the order Mononegavirales.
Members of this genus are significant pathogens in veterinary medicine, including Canine Distemper Virus (CDV), Rinderpest Virus, and Peste des Petits Ruminants Virus (PPRV).
Detailed Explanation:
Morbilliviruses are enveloped, pleomorphic particles with helical nucleocapsid symmetry.
The viral genome consists of a single molecule of linear, non-segmented, single-stranded, negative-sense RNA ($15$--$16$ kilobases in length).
Because the genomic RNA is negative-sense, it cannot be directly translated by the host cell ribosomes.
The virion must carry its own RNA-dependent RNA polymerase (L and P proteins) into the host cell to transcribe the genomic negative strand into positive-sense mRNA templates.
This transcription process follows the sequential stop-start mechanism guided by gene junctions, producing distinct monocistronic mRNAs for viral protein synthesis.

Step 2: Final Answer:
Morbilliviruses are single-stranded, negative-sense RNA viruses.