New Technique for Aseptic Removal of Chick Embryo from Egg

H. A. Penna
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One of the chief difficulties in the preparation of yellow fever vaccine (Theiler and Smith (1), Smith, Penna and Paoliello (2)) is the filtration of the chick embryo suspension through the Seitz, E. K., disc. This filter retains variable amounts of the virus and even becomes entirely blocked if an attempt is made to use a suspension containing more than 15 per cent of chick embryo tissue. The elimination of filtration from the method of vaccine preparation would avoid a serious loss of virus and at the same time permit the use of whatever suspension of chick embryo may prove most satisfactory.

Repeated tests show that the chick embryo is rarely contaminated while in the egg. On the other hand, cultural methods indicate that a high percentage of egg shells contain living bacteria even after they have been painted with tincture of iodine and washed with alcohol.

Author Notes

From the Laboratory of the Yellow Fever Service, Rio de Janeiro, maintained by the Ministry of Education and Health of Brazil in coöperation with the International Health Division of The Rockefeller Foundation.