An aluminum marker for the differentiation and separation of virulent and attenuated polioviruses.

A new character, the A marker, for polioviruses is described. In the presence of Al(+++) (1 to 100 mM) attenuated, but not virulent, strains of type 1 and type 2 polioviruses are stabilized so that they resist thermal inactivation at 50 degrees C. Differences between the attenuated and virulent type 3 strains studied were of the opposite character and less marked. By the use of optimal concentrations of Al(+++) (12 mM for type 1 and 1 mM for type 2) attenuated strains can be separated from mixtures containing virulent type 1 or 2 strains. The A marker was found to be correlated with the d but not the rct/40 or T marker. The A marker has been used for following genetic changes of vaccine strains after their multiplication in man.