Escaping alveolar macrophage endosomal retention explains massive expansion of SARS-CoV-2 delta variant

Dear Editor,Genetic variant Delta(B.1.617.2)of severe acute respiratory syndrome coronavirus 2(SARS-CoV-2),which possesses a remarkable ability to transmit and spread,is currently becoming predominant worldwide.Despite its great harm to human beings,how the Delta variant with T478K,P681R and L452R mutations achieves its ultrafast spread remains elusive.Entry of SARS-CoV-2 into host cells is mediated by a rapid enzymatic hydrolysis.