Infection of many respiratory viruses requires that membrane proteins on the viral surface be properly digested (cleaved) by host proteases. This knowledge is based on historical studies of Sendai virus in the 1970s. This understanding is also essential for understanding the current pandemic virus, SARS-CoV-2.

Takeda M. Cleavage activation of respiratory viruses – Half a century of history from Sendai virus to SARS-CoV-2. Jpn J Infect Dis. in press

https://doi.org/10.7883/yoken.JJID.2023.353