Moreover, RSV infection, that precedes the OVA induction of asthma, leads to significantly milder course; this could possibly be ascribed to the shift in Th1/Th2 balance among γδ T cells, namely the elevated expression of IFN-γ (Th1-like γδ T) and decreased that of IL-4 (Th2-like γδ T) (Zhang et al. 2013b). This evidence concerns the gene IL4 and asthma.