Cellular Proteinases and Viral Infection: Influenza Virus, Sendai Virus, and HIV-1

Publisher Summary This chapter deals with the cellular proteinases and viral infection. It discusses the processing proteinase in the airway, which determines the infectious tropism of the influenza and Sendai viruses as well as the cellular processing proteinase, which may play a role in the extracellular processing of HIV-1 gp120 before virus entry. The chapter presents the role of tryptase clara in triggering the infectivity of the influenzaA and Sendai viruses. It also reports processing proteases of the fusion glycoprotein (F 0 ) protein of Sendai virus and hemagglutinin (HA) of human influenza virus. The F 0 protein of Sendai virus is cleaved by trypsin in vitro and by blood clotting factor Xa in the chorioallantoic fluid. Furthermore, this chapter turns to the discussion of human T-cell proteinase: tryptase TL 2 . In the process of HIV-1 entry, envelope glycoprotein gp120 is cleaved, within the third variable domain (V3) loop, into two fragments. The two host proteases discussed in this chapter, tryptase Clara and tryptase TL 2 , illustrate the role of cellular factors in the infection process.