Enhancement of parainfluenza 2 virus hemagglutinin.

A comparison was made of the three previously described methods of enhancement of parainfluenza 2 virus hemagglutinin (HA): ultrasonic oscillation, adsorption to erythrocytes and elution (AE), and Tween-ether (TE) treatment. TE treatment resulted in the maximal elevation of HA titer, complete loss of infectivity, and the maximal loss of heat stability of HA. Ultrasonic oscillation caused the least elevation of HA titer, minimal loss of infectivity, and the least loss of heat stability of both HA and infectivity. The effect of AE remained intermediate. It is suggested that the changes produced by these three methods are varying degrees of disruption of virus particles. Growth studies on parainfluenza 2 virus are also presented.