The Orthoreovirus family is one of the most widely distributed groups of viruses. Mammalian Orthoreovirus (MRV) belongs to the genus Orthoreovirus, which mainly infects the respiratory and intestinal tracts of mammals. The intact virus particle is icosahedral, with a diameter of about 60-80 nm and no capsule; the viral nucleic acid is about 18-27 kb and is wrapped by a double-layer protein capsid. According to the erythrocyte agglutination activity MRV is divided into three serotypes: serotype 1 (T1L, Long), serotype 2 (T2J, Jone) and serotype 3 (T3D, Dearing; T3A, Abney). Among them, wild-type or modified Orthoreovirus is a tumor lysis virus, which can replicate and proliferate by targeting tumor cells in large numbers, and can also achieve its tumor lysis effect on tumor cells by activating the Ras signaling pathway and inducing apoptosis and autophagy in tumor cells.

Schematic diagram of Orthoreovirus particles (Benavente J et al., Virus research, 2007)