Pathogenesis of avian influenza: role of the haemagglutinin cleavage site motif

The pathogenicity of highly pathogenic avian influenza viruses (HPAIVs) is highly dependent on the presence of a polybasic haemagglutinin cleavage site (HACS) motif. This study demonstrated that HPAIV replication in chickens occurs primarily in vascular endothelium and is modulated by the molecular composition of the HACS motif.