Zou, Z et al. found that with H5N1 infection, the RAS was involved and final concentration of Ang II were able to be used as prognostic indicators[27].These studies suggested that with viral infection, the pathogens could damage the homeostasis of the lung RAS, alter the local blood pressure and vascular permeability, and aggravate the imbalance of pro-inflammatory and anti-inflammatory mediators, thus affecting the occurrence and development of lung injury. Here, AGT is linked to viral infectious disease.