<P> 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 . </P> <P> Positive - sense ssRNA viruses have genetic material that can function both as a genome and as messenger RNA; it can be directly translated into protein in the host cell by host ribosomes . The first proteins to be expressed after infection serve genome replication functions; they recruit the positive - strand viral genome to viral replication complexes (VRCs) formed in association with intracellular membranes . VRCs contain proteins of both viral and host cell origin, and may be associated with the membranes of a variety of organelles, often the rough endoplasmic reticulum, but also including membranes derived from mitochondria, vacuoles, the Golgi apparatus, chloroplasts, peroxisomes, plasma membranes, autophagosomal membranes, and novel cytoplasmic compartments . The replication of the positive - sense ssRNA genome proceeds through double - stranded RNA intermediates, and the purpose of replication in these membranous invaginations may be the avoidance of cellular response to the presence of dsRNA . In many cases subgenomic RNAs are also created during replication . After infection, the entirety of the host cell's translation machinery may be diverted to the production of viral proteins as a result of the very high affinity for ribosomes of the viral genome's internal ribosome entry site (IRES) elements; in some viruses, such as poliovirus and rhinoviruses, normal protein synthesis is further disrupted by viral proteases degrading components required to initiate translation of cellular mRNA . </P> <P> All positive - sense ssRNA virus genomes encode RNA - dependent RNA polymerase (RdRP), a viral protein that synthesizes RNA from an RNA template . Host cell proteins recruited by positive - sense ssRNA viruses during replication include RNA - binding proteins, chaperone proteins, and membrane remodeling and lipid synthesis proteins, which collectively participate in exploiting the cell's secretory pathway for viral replication . </P> <P> The genome of a positive - sense ssRNA virus usually contains relatively few genes, usually between three and ten, including an RdRP . Coronaviruses have the largest known RNA genomes, up to 32 kilobases in length, and likely possess replication proofreading mechanisms in the form of a proofreading exoribonuclease, non-structural protein 14, that is otherwise not found in RNA viruses . </P>

To which group does a small non enveloped single-stranded