Partitiviruses

Partitiviruses are a family of non-enveloped, segmented, double-stranded RNA (dsRNA) viruses. Their name derives from the Latin word "partitus," meaning divided or separated, referring to their segmented genome. Each segment is encapsidated within its own protein shell, forming distinct virus particles. These particles are typically isometric, with a diameter of about 30-50 nanometers. The genome of partitiviruses is bipartite, meaning it consists of two segments. Each segment is linear and contains both coding and non-coding regions. Replication of partitiviruses occurs entirely within the cytoplasm of the host cell. They do not encode their own RNA-dependent RNA polymerase; instead, they carry it within the virion. Partitiviruses infect a wide range of hosts, including fungi, plants, and protozoa, but have not been found to infect animals. Their transmission is often vertical, passed from parent to offspring, and can also occur horizontally through various mechanisms depending on the host. In fungi, they are often associated with the phenomenon of "mycovirus-induced hypovirulence," where the presence of the virus can reduce the pathogenicity of the fungal host. In plants, some partitiviruses can cause mild or asymptomatic infections, while others may lead to visible symptoms. Diagnosis of partitivirus infections typically involves molecular methods such as RT-PCR and sequencing.