Characterization of the Reconstructed 1918 Spanish Influenza Pandemic Virus (NOT OPEN ACCESS) SUMMARY: Influenza viruses require a proteolytic enzyme (an enzyme that can cut or cleave proteins), like trypsin, in order to activate a surface protein that allows them to attach/infect our cells. Since viruses can only replicate inside cells, having this proteolytic enzyme is… Continue reading Understanding the Spanish Flu Virus