+ssRNA

Definition

+ssRNA, or positive-sense single-stranded RNA, is a type of viral genetic material that can act directly as mRNA in host cells. This allows for immediate translation by the host's ribosomes during infection.

5 Must Know Facts For Your Next Test

1. Positive-sense single-stranded RNA (+ssRNA) viruses include pathogens like poliovirus and hepatitis C virus.
2. +ssRNA genomes are infectious by themselves because they can immediately be translated into proteins once inside the host cell.
3. The replication of +ssRNA viruses typically occurs in the cytoplasm of the host cell.
4. +ssRNA viruses often have high mutation rates due to lack of proofreading mechanisms during replication.
5. Some +ssRNA viruses encode their own RNA-dependent RNA polymerase to replicate their genome.

Review Questions

• What is the primary advantage of +ssRNA for a virus upon entering a host cell?
• Name two diseases caused by +ssRNA viruses.
• Where does the replication of +ssRNA viruses generally occur within the host cell?

Related terms

-ssRNA: Negative-sense single-stranded RNA that must be converted into positive-sense RNA before translation.

mRNA:

Messenger RNA that carries genetic information from DNA to ribosomes for protein synthesis.

Capsid:

The protein shell that encloses the viral genome.