*2.11. Cytotoxicity Assay*

Cell damages were evaluated by measuring lactate dehydrogenase (LDH) release. Supernatants of infected cells were recovered and subjected to CytoTox 96 ® nonradioactive cytotoxicity assay (Promega, Madison, WI, USA) according to manufacturer instructions. Absorbance of converted dye was measured at 490 nm using a microplate reader (Tecan, Mannedorf, Switzerland). Results of LDH activity in cell supernatants are presented with subtraction of values from mock-infected cells.

#### *2.12. Measurement of the IFN-*β *Pathway Activation*

Activation of the Interferon regulatory factors (IRF) pathway was monitored by measuring *Lucia* luciferase activity in A549-Dual ™ cells. It was evaluated using QUANTI-Luc substrate (InvivoGen, San Diego, CA, USA) according to manufacturer's recommendations. IRF-induced luciferase levels were quantified using a FLUOstar Omega Microplate Reader (BMG LABTECH, O ffenburg, Germany). Results are presented with subtraction of values from mock-infected cells.
