IRF3 and infection: Additionally, titers of WNVKUN or A30A′ in the serum of infected mice (weanling and adult IRF3−/−/7−/−) and levels of CPE induced in IFNAR−/− MEFs were similar [23] and unpublished data) suggesting that NS1′ protein may not have an essential function in the viral lifecycle in these models of infection [23], [30].