Tospovirus

Tospovirus is a genus of plant-infecting viruses in the order Bunyavirales, family Phenuiviridae. Members are enveloped, with a tripartite, negative-sense RNA genome and are transmitted by thrips in a persistent-propagative cycle. The type species is Tomato spotted wilt virus (TSWV); other well-known members include Iris yellow spot virus (IYSV) and Tomato chlorotic spot virus (TCSV).

The genome consists of three segments designated L, M, and S. The L segment encodes the RNA-dependent RNA polymerase, essential for replication. The S segment encodes the nucleocapsid protein and a nonstructural protein (NSs) involved in silencing suppression. The M segment encodes the nonstructural protein NSm and the envelope glycoproteins Gn and GC, which form the viral envelope. NSs acts as an RNA silencing suppressor, contributing to virulence, while NSm is implicated in movement within the plant.

Transmission occurs primarily through thrips, especially species in the family Thripidae such as Frankliniella occidentalis. Acquisition by feeding during the larval stages followed by replication in the vector enables the virus to be transmitted by adults in a persistent-propagative manner. Tospoviruses have a broad host range, affecting many economically important crops and ornamentals, and can cause symptoms such as rings, mottling, necrosis, stunting, and yield losses.

Management relies on prevention and vector control, as there are no curative treatments. Approaches include minimizing thrips activity, destroying infected plants, using resistant or tolerant cultivars where available, and implementing integrated pest management strategies. Diagnostics employ serology and molecular methods such as ELISA and RT-PCR to detect and identify specific Tospovirus species.