An attempt to analyse the functional difference between various mumps virus strains.

Enzymatic activity of N-acetylneuraminidase of ten various strains of mumps virus was compared. From the viewpoint of their biological properties, these strains could be classified as laboratory, neurovirulent, and vaccinal (attenuated) ones. The enzymatic activity was evaluated by Scatchard's plot which enables to interpret it according to polarity of the cooperativity of enzymes' binding sites. Laboratory strains of the mumps virus demonstrated an independent type of cooperativity, while vaccinal (attenuated) ones showed a positive type of cooperation.