A positive-sense single-stranded RNA virus (or (+)ssRNA virus) is a virus that uses positive sense, single-stranded RNA as its genetic material. Single stranded RNA viruses are classified as positive or negative depending on the sense or polarity of the RNA. The positive-sense viral RNA genome can also serve as messenger RNA and can be translated into protein in the host cell. Positive-sense ssRNA viruses belong to Group IV in the Baltimore classification. Positive-sense RNA viruses account for a large fraction of known viruses, including many pathogens such as the hepatitis C virus, West Nile virus, dengue virus, and SARS and MERS coronaviruses, as well as less clinically serious pathogens such as the rhinoviruses that cause the common cold.