Novel Toscana Virus Reverse Genetics System Establishes NSs as an Antagonist of Type I Interferon Responses

• Published in: Viruses 2020-04, Vol.12 (4), p.400
• Main Authors: Woelfl, Franziska, Léger, Psylvia, Oreshkova, Nadia, Pahmeier, Felix, Windhaber, Stefan, Koch, Jana, Stanifer, Megan, Roman Sosa, Gleyder, Uckeley, Zina M, Rey, Felix A, Boulant, Steeve, Kortekaas, Jeroen, Wichgers Schreur, Paul J, Lozach, Pierre-Yves
• Format: Article
• Language: English
• Subjects: A549 Cells; Amino acids; Animals; Antagonists (Biochemistry); Antibiotics; Antibodies, Viral - immunology; Arbovirus; Bunyavirales; Bunyaviruses; Cell Line; Chlorocebus aethiops; Cricetinae; DNA-directed RNA polymerase; DNA-Directed RNA Polymerases - genetics; Genetic aspects; Genetic engineering; Genome, Viral; Genomes; Glycoproteins; Health aspects; Heparan sulfate; Humans; Infections; Insecta; Interferon; Interferon-beta - antagonists & inhibitors; Interferon-beta - immunology; Kidney - cytology; Life cycles; Life Sciences; Membranes; Meningoencephalitis; Microbiology and Parasitology; Microscopy; mRNA; Mutants; Mutation; neglected diseases; Penicillin; Phenuiviridae; Phlebovirus; Plasmids; Polyclonal antibodies; Proteins; Reverse Genetics; RNA polymerase; Sandfly fever Naples virus - genetics; Sandfly fever Naples virus - immunology; Testing; Vero Cells; Viral Nonstructural Proteins - genetics; Viral Nonstructural Proteins - immunology; Viral Proteins - genetics; Virology; Viruses; β-Interferon
• ISSN: 1999-4915; 1999-4915
• DOI: 10.3390/v12040400

The sand fly-borne Toscana virus (TOSV) is the major cause of human meningoencephalitis in the Mediterranean basin during the summer season. In this work, we have developed a T7 RNA polymerase-driven reverse genetics system to recover infectious particles of a lineage B strain of TOSV. The viral protein pattern and growth properties of the rescued virus (rTOSV) were found to be similar to those of the corresponding wild-type (wt) virus. Using this system, we genetically engineered a TOSV mutant lacking expression of the non-structural protein NSs (rTOSVɸNSs). Unlike rTOSV and the wt virus, rTOSVɸNSs was unable to (i) suppress interferon (IFN)-b messenger RNA induction; and (ii) grow efficiently in cells producing IFN-b. Together, our results highlight the importance of NSs for TOSV in evading the IFN response and provide a comprehensive toolbox to investigate the TOSV life cycle in mammalian and insect host cells, including several novel polyclonal antibodies.