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Characterisation of the antiviral RNA interference response to Toscana virus in sand fly cells

Toscana virus (TOSV) and other related human pathogenic arboviruses are transmitted by phlebotomine sand flies. TOSV has been reported in most countries surrounding the Mediterranean Sea. Infection in humans may result in febrile illness as well as non-lethal meningitis and encephalitis. Understanding vector-arbovirus interactions is crucial to improving our knowledge of how arboviruses spread. For instance, immune responses induce by the arthropod vectors upon infection play a significant role. However, the antiviral immunity of phlebotomine sand flies is poorly understood. Along this line, the Bunya team participated to a study led by Prof. Alain Kohl from the CVR of Glasgow showing that the exogenous siRNA (exo-siRNA) pathway is active in a Phlebotomus papatasi-derived cell line. Indeed, specific 21 nucleotide virus-derived small interfering RNAs were detected upon TOSV infection. In addition, the exo-siRNA effector named Ago2 was identified in this cell line, and knocking down its expression significantly disrupt the exo-siRNA pathway. Overall, these data show for the first time that the exo-siRNA pathway is induced as an antiviral response against a sand fly transmitted virus, TOSV. 

Read the paper published Plos Pathogens