Y-shaped RNA secondary structure of a noncoding region in the genomic RNA of tick-borne encephalitis virus affects pathogenicity.

Tick-borne encephalitis virus (TBEV) is a zoonotic virus that causes encephalitis in humans. Various deletions have been reported in a variable region of the 3' untranslated region of the TBEV genome. This study analyzed the role of a Y-shaped secondary structure in the pathogenicity of TBEV by using reverse genetics. Deletion of the structure increased the mortality rate of virus-infected mice but did not affect the virus multiplication in cultured cells and organs. The results indicate that the secondary structure is involved in the regulation of TBEV pathogenesis.