Armstrong Mouse Adapted Poliomyelitis Virus

Abstract

Summary

It has been demonstrated that in the mouse, employing the Armstrong mouse adapted Lansing strain of virus, a definite quantity of virus can be rendered more effective in producing infection by suspending it in a menstruum of low pH. By progressively decreasing the pH from 7.0 to 4.0 the effectiveness of the virus was increased in a step-like manner. The virus suspension at pH 4.0 appeared to be as effective as from 4 to 16 times as much virus at pH 7.0. At present the mechanism is not understood, although numerous conjectures might be made both in respect to local and possible systemic effects. Experiments to investigate the mechanism are in progress.

We have not compared the effect of neutralized enteric filtrate to that of neutral saline in monkeys and cotton rats, as was done by Toomey and by Toomey and Takacs, since these animals were not readily available in sufficiently large numbers to permit clear-cut evaluation of results. However, in the mouse, the effect of the Armstrong virus was not altered by combining it with enteric filtrate. At either a low pH or at pH 7.6 buffered saline has been shown to produce results of an entirely comparable nature.