title: Plaque formation by avian infectious bronchitis virus in primary chick embryo fibroblast cells in the presence of trypsin.
abstract: Ten strains of avian infectious bronchitis virus (IBV) were titrated as plaque-forming units in primary chick embryo fibroblast cells. In the absence of trypsin, plaques were only formed by Beaudette-42 and Iowa-609 strains. When trypsin was incorporated in the overlay medium of cell monolayers, all the IBV strains tested produced plaques within 4 days after inoculation. Incorporation of 20-40 microgram of trypsin per ml of the overlay medium seemed to be suitable for plaque formation of IBV. A preliminary investigation was made of the mode of action of trypsin.
mesh_terms: D000818:Animals; D002478:Cells, Cultured; D002642:Chick Embryo; D003332:Coronaviridae / Q000254:growth & development*; D003470:Culture Media; D005347:Fibroblasts / Q000382:microbiology*; D001351:Infectious bronchitis virus / Q000254:growth & development*; D014357:Trypsin / Q000494:pharmacology*; D014361:Trypsin Inhibitors / Q000494:pharmacology; D010948:Viral Plaque Assay
chemical_list: D003470:Culture Media; D014361:Trypsin Inhibitors; D014357:Trypsin