English: Replication and pathogenesis of Equine Influenza Virus (EIV). EIV damages the upper and lower respiratory tract's ciliated epithelial cells thereby causes inability to clear foreign substances. Spike glycoprotein HA fastens to the receptors present on the respiratory epithelial cells and it enters the cells by endocytosis. After endocytosis, EIV undergoes fusion and uncoating. Opening of M2 channel leads to proton entry and subsequent release of viral RNA followed by synthesis of viral structures leading to assembly of EIV. EIV is released from the infected cells by the process of budding.