CXCR4 and viral infectious disease: Interestingly, at this time point, WT virus infection significantly increases the expression of genes involved in leukocyte chemoattraction and especially in the recruitment and activation of polymorphonuclear granulocytes: IL3 signaling, GM-CSF signaling, CXCL1 signaling, CCR3 signaling and CXCR4 signaling (Fig. 3C).