IL1B and infection: More importantly, as observed earlier, the amount of secreted IL-1β correlated with the significantly lower levels of type I IFN (Figure 6D, r = 0.885, p<0.0001) and RIG-I (transcript r = 0.593, p = 0.0327, Figure 6E; protein, Figure 6F and G) expressed during infection with rUSSR-NS1 1918 compared to rUSSR.