Inactivation of Poliomyelitis Virus in Relation to Gastric and Intestinal Digestion.

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Abstract
Expts. were designed to test the inactivating effect of acidities within the range obtaining in the human stomach during digestion, with and without pepsin. The mouse-adapted Lansing strain was exposed to acidities of pH 1-4 for periods of 5 min. to 4 hrs. After exposure the material, re-adjusted to approx. neutrality, was injd. intracerebrally into white Swiss mice. At pH 1, virus was completely inactivated in 5 min.; at pH 1.5, it was partially inactivated in 5 min. and completely in 15 min.; at pH 2, it was partially inactivated at 2 hrs. and completely at 4 hrs.; at pH 3 and 4, no inactivation occurred. The effect of trypsin was tested on rhesus monkeys, using a freshly isolated human strain, by intranasal inoculation. No inactivating effect was noted; trypsin appeared to heighten the infectivity of the virus. It is concluded that under natural conditions, swallowed virus is destroyed in part during gastric digestion but not in toto, and that any virus gaining access to the intestine escapes further inactivation.