Going forward, we focused on the first 4 days of infection as this time point represents the peak tissue-dwelling stage of Hpb and also preceded a detectable number of IL-4-producing SILP Th2 cells, representing onset of the adaptive immune response (Fig. S1).12 To test whether Hpb-induced NK cell accumulation was dependent on the genetic background of the mice, we also infected BALB/c mice. Here, IL4 is linked to infection.