title: Activation of Sendai virus infectivity by an enzyme in chicken amniotic fluid.
abstract: Sendai virus grown in LLC-MK2 cells is known to have low infectivity, no detectable haemolysing ability and predominantly uncleaved F glycoprotein. Treatment of such virus with chicken amniotic fluid resulted in a 10(3)- to 10(4)-fold increase in infectivity, the development of haemolysing ability, and cleavage of the F glycoprotein. The 'Sendai activating enzyme' (SAE) responsible for these effects required the presence of 1 mM-Ca2+ ions for maximum activity. It was inhibited by phenylmethylsulphonyl fluoride and soybean trypsin inhibitor but was unaffected by sulphydryl-blocking agents. The results of gel filtration tests suggested that the molecular weight of SAE was about 55 000. SAE may be the natural proteolytic activator of Sendai virus in a soluble form.
mesh_terms: D000482:Allantois / Q000201:enzymology; D000653:Amniotic Fluid / Q000201:enzymology; D000818:Animals; D002118:Calcium / Q000494:pharmacology; D002642:Chick Embryo; D010450:Endopeptidases / Q000032:analysis / Q000494:pharmacology*; D008970:Molecular Weight; D010222:Parainfluenza Virus 1, Human / Q000187:drug effects / Q000254:growth & development*; D010447:Peptide Hydrolases / Q000494:pharmacology; D011480:Protease Inhibitors / Q000494:pharmacology; D014357:Trypsin / Q000494:pharmacology; D014360:Trypsin Inhibitor, Kunitz Soybean / Q000494:pharmacology; D010948:Viral Plaque Assay; D014764:Viral Proteins / Q000096:biosynthesis; D014775:Virus Activation / Q000187:drug effects*
chemical_list: D011480:Protease Inhibitors; D014764:Viral Proteins; D014360:Trypsin Inhibitor, Kunitz Soybean; D010450:Endopeptidases; D010447:Peptide Hydrolases; C037550:Sendai activating enzyme; D014357:Trypsin; D002118:Calcium