Arteriviridae and Roniviridae

Viruses in the Arteriviridae and Roniviridae families have very different virion morphology, but the grouping reflects their common and distinctive replication strategy that uses a nested set of 3´ coterminal subgenomic messenger RNAs (mRNAs). The family Roniviridae contains viruses that are detected only in crustaceans, specifically, several genotypes of gill-associated and yellow head viruses. The host range of arteriviruses is highly restricted, and all arteriviruses share the capacity to establish asymptomatic prolonged or persistent infections in their respective natural hosts; most can cause severe disease in certain circumstances. The family Arteriviridae comprises a single genus, Arterivirus, which contains all member viruses, and the family Roniviridae contains a single genus, Okavirus. Arterivirus virions are enveloped, spherical, and 45–60 nm in diameter, which is only about half the size of those of coronaviruses. Arteriviruses replicate in macrophages and a very limited number of other cell types within their respective hosts. The host range of arteriviruses is highly restricted, and the viruses typically grow in vitro only in cultured macrophages, macrophage cell lines, and a few other cell lines. Some arteriviruses effectively can subvert protective host innate immune responses, including apoptosis of infected macrophages and interferon signaling pathways.