KRAS and infection: All mice infected with the parental strain WN-IS98 died at day 7 p.i., whereas only one mouse infected with WN-IT08 and 2 mice infected with IS98-3′NS4B/NS5 died at the same day p.i. Delayed death during infection by IS98-3′NS2B/NS3/NS4A/NS4B became evident on day 8 p.i. Kruskal-Wallis analysis at 7 days p.i. showed a significant difference in mortality between IS98-3′NS2B/NS3/NS4A/NS4B and WN-IS98 (p < 0.01) and between WN-IT08 and WN-IS98 (p < 0.05).