Molecular biology of Tomato spotted wilt virus: An update

Abstract: Advances in understanding of Tomato spotted wilt virus (TSWV) molecular biology are reviewed. TSWV, a type species of the genus Tospovirus, is an enveloped virus that causes high economical losses in many crops worldwide. It is transmitted by several species of thrips and multiplies in insect cells. The most important vector is Frankliniella occidentalis which transmits TSWV in a persistent propagative manner. Several factors are known from both virus and vector side which plays important role in virus acquisition by thrips and its subsequent transfer. TSWV is a segmented negatively strand RNA virus. RNA of TSWV is partitioned among three negative or ambisense single stranded RNA (ssRNA) labeled as L, M and S in order of decreasing size, (approximately 8897, 4821 and 2916 nucleotides long, respectively). These RNA segments encode various proteins like N and Ns by S RNA; NSm and G1/G2 by M RNA and RdRp by L RNA. Intergenic region present in M and S RNA of TSWV helps in proper transcription of different genes encoded by M and S RNA. The different proteins encoded by TSWV genome help the virus in protection, cellular movements, vector transmission, replication and recently in RNA silencing suppressor activity. The present review focuses on basic structure, genome organization, molecular basis of transmission and recent advances in TSWV detection.