Influenza Virus Infects and Replicates in Airway Epithelial Cells $\alpha$ And IFN-

Influenza virus infects and replicates in airway epithelial cells. This virus has a segmented single-stranded RNA genome. Experiments to determine which innate immune sensors were recognizing the virus and inducing production of type I IFNs (IFN- $\alpha$ and IFN- $\beta$ ) were performed. For these studies, mice were infected with Influenza A virus by the intranasal route, which leads to a potent infection in the lungs. Two days post-infection, Type I IFNs were measured in the lung; A shows the results.
a) Name two innate sensor categories that are likely involved in recognizing influenza virus.
b) A common symptom of virus infections is fever. Which innate receptor sensing pathway is most likely responsible for this response, and how is it induced?
Several cell culture lines of epithelial cells, called "Cell Line A, B, or C," are incubated with 10⁴ infectious particles of influenza virus, and viral titers in the culture media are measured 2 days later. Looking at the results of this experiment, it is apparent that the three lines do not all show the same response to the virus. To investigate these differences, mixing experiments are performed, where cells from two different cell lines are mixed together at a 1:1 ratio before the Influenza infection.
c) Based on the results shown in Figure , propose an explanation for these data.