ESTIMATION OF THE PURITY OF PREPARATIONS OF ELEMENTARY BODIES OF VACCINIA.
A method of estimating the purity of preparations of elementary bodies of vaccinia is described. It depends on the comparison of the number of infective units of virus in a given material with the number of elementary bodies. The latter figure is estimated from the dry weight of the preparation by means of a calculated value for the weight of a single dehydrated elementary body. Values for the ratio of infective units of vaccine virus to elementary bodies varied between 1 : 2.4 and 1 : 9.2 in seven consecutive experiments; the average was 1:4.2. These ratios indicate a high degree of purity of the preparation. Moreover, they indicate that a relatively high percentage of the elementary bodies in the preparations was infective.
Smadel
J E
JE
Hospital of The Rockefeller Institute for Medical Research, and the Laboratories of the International Health Division of The Rockefeller Foundation, New York.
Rivers
T M
TM
Pickels
E G
EG