High yield growth and purification of human parainfluenza type 3 virus and initial analysis of viral structural proteins.

Structural proteins from a large-plaque variant (LPV) of human parainfluenza type 3 virus were analysed by electrophoresis on Laemmli-type polyacrylamide gels. High virus concentrations were obtained by growth in BS-C-1 cells cultivated on microcarrier beads. Purification of the virus in composite equilibrium gradients of potassium tartrate:glycerol resulted in 25% recovery of input infectivity and a preparation containing less than 0.08% of input host cell protein and RNA. Parainfluenza type 3 virus equilibrated at a density of 1.20 g/ml in these gradients. Analysis by polyacrylamide gel electrophoresis of 3H-glucosamine-labelled virus taken from peak gradient fractions revealed 8 or 9 major virion peptides, ranging in mol. wt. from 17 x 10(3) to 125 x 10(3) (17K to 125K), two of which were glycoproteins. The sum of the estimated mol. wt. of these peptides, 501.5K to 570.5K, does not exceed the estimated genomic potential of other paramyxoviruses.