4F23:
reference: Insights into Avian Influenza Virus Pathogenicity: the Hemagglutinin Precursor HA0 of Subtype H16 Has an Alpha-Helix Structure in Its Cleavage Site with Inefficient HA1/HA2 Cleavage., Lu X, Shi Y, Gao F, Xiao H, Wang M, Qi J, Gao GF, J Virol. 2012 Dec;86(23):12861-70. doi: 10.1128/JVI.01606-12. Epub 2012 Sep 19. PMID: 22993148

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