Structural insights into viral genome replication by the severe fever with thrombocytopenia syndrome virus L protein

 Severe fever with thrombocytopenia syndrome virus is a new emerging disease that currently endemic in East Asian countries. Cases of transmission of SFTS virus from human to human have made it a new global phenomenon, so proper countermeasures are needed as a prevention measurement. The SFTS replication process involves the role of the L segment which encodes the enzyme RNA dependent RNA polymerase (RdRp). The study demonstrated that L protein initiate the mechanism of SFTS replication. Using in-vitro biochemical and cell-based mini replicon assay, the study reconstructed the 5 different structures of SFTS virus L protein. L protein initiates the replication of SFTS by conformed the viral 5’ into hook-like shape, formed a duplex in the 3’ RNA terminus for initiation in RdRp active site, and accommodates the duplex formation of a 10 bp product template. The duplex of the product afterwards split with the template to the 3’ secondary binding site. The SFTS L protein undergoes additional remodeling and later advances from pre-initiation to the late-stage elongation. The study found a solid basis for future research into issues how the SFTS virus L protein catalyses viral transcription.
(MA)