Characterization of Human Parainfluenza Viruses. I. The Structural Proteins of Parainfluenza Virus 2 and their Synthesis in Infected Cells

Faculty of Medicine, The University of Newcastle, David Maddison Clinical Sciences Building, Royal Newcastle Hospital, Newcastle, New South Wales 2300, Australia Two strains of human parainfluenza virus 2 (HPV2), P 2 1972/6 and P 2 1980, grow to high titre in MEK 3 cells, and their structural proteins and virus-induced protein synthesis have been characterized by gel electrophoresis and immunoprecipitation. Purified viruses contain seven polypeptides, including cellular actin: L (175K mol. wt.), HN (72K to 74K), NP (66K to 67K), F 1 (52K to 58K), P (49K), A (44.5K) and M (39K). Virus-induced polypeptide synthesis was first detected at 8 h post-infection with the appearance of NP; other major structural proteins were detected from 10 to 12 h after infection and onwards. The synthesis of both the structural glycoproteins was demonstrated, although proteolytic processing could not be detected. Reproducible differences in the gel migration of the HN, F 1 and NP polypeptides were found in whole virus, in infected cells and cells subjected to immunoprecipitation. These differences may reflect genetic diversity within HPV2 and provide a means of probing the molecular epidemiology of these viruses. Keywords: parainfluenza viruses, human, protein, glycoprotein, characterization Received 6 April 1983; accepted 29 June 1983.