Studies with dried airborne vaccinia virus in a small environmental chamber

Dried vaccinia virus was found to be very stable in aerosol form in our chamber at a temperature of 75°F and a relative humidity (RH) of 85% when the virus was protected with 1.5% lysine, 1.5% sodium glutamate, 0.5% isoniazid, 0.5% thiourea, and either 2.5% heart infusion broth (HIB) or a combination of 3.75% lactose plus 1.25% raffinose prior to freeze‐drying. Utilization of the Environmental chamber technique resulted in ( a ) selection of two diluents which protected vaccinia virus against the effects of high relative humidity, ( b ) measurement of the effect of various chemical additives in the diluents, and ( c ) quantitative measurement of the moisture absorbed by the various dried products.