Neutrophil infiltration in infected lungs during the early infection stage of respiratory H1N1 infection was significantly decreased in the CXCL5-/- mouse model (Figures 5A, C), which suggests that CXCL5 positively regulates neutrophil influx to infected lungs during the innate immunity stage in the H1N1 infection model. This evidence concerns the gene CXCL5 and infection.