Totivirus

Totiviruses are a genus of dsRNA viruses in the family Totiviridae. They are characterized by their large, unenveloped icosahedral virions that contain a single molecule of double-stranded RNA (dsRNA). This dsRNA genome is bipartite, meaning it is divided into two separate RNA molecules, each encoding one or two proteins. The most notable feature of totiviruses is the presence of an RNA-dependent RNA polymerase (RdRp) enzyme, which is essential for viral replication, packaged within the virion. Totiviruses infect a wide range of eukaryotic hosts, including fungi, protozoa, and insects. They are generally considered to be non-pathogenic, although some have been associated with detrimental effects on their hosts, such as reduced growth rates or altered phenotypes. Transmission typically occurs vertically, from parent to offspring, or horizontally through cell-to-cell contact. Replication of totiviruses occurs entirely within the cytoplasm of the host cell. The dsRNA genome is transcribed by the viral RdRp to produce subgenomic mRNAs, which are then translated into viral proteins. The genome is also replicated by the RdRp. New virions are assembled within the cytoplasm and released upon cell lysis or through budding. While totiviruses are not a significant threat to human health, they are valuable tools for studying viral replication mechanisms and gene expression in eukaryotic systems. Their genetic stability and ease of manipulation make them suitable for various biotechnological applications.