In this way inhaled pathogens and particulate matter trapped by the airway mucus can be removed by swallowing or coughing. This process is an important self-defense mechanism of the respiratory system and its failure may lead to chronic infections and impaired lung function [4].Furthermore, the virus has to survive to the immune surveillance of the host. Natural and adaptive immunity are alerted, and will start mounting an immune response to the invasive guest. A struggle develops between the speed of virus replication and diffusion, and the inflammatory response trying to contain it. Sometimes the inflammatory response gets out of control, and a cytokine storm may happen, adding further damage to the viral infection, causing acute lung injury and leading the patient to death [5,6].
The infective processThe SARS-CoV-2 and its interactions CoVs have a complex organization (Figure 1) containing four or five structural proteins mixed with some minor components that include nonstructural and host cell-derived proteins [7]. All viral particles display on their surface Spike (S), Envelope (E) and Membrane (M) structural proteins [8] (Insert Fig 1).These surface proteins interact with host cell membranes at the beginning of infection, and the S protein is responsible for the fusion