Abstract
In labelling the PR 8 strain of influenza virus with radioactive phosphorus, Maitland type tissue culture was employed. Here a piece of chorioallantoic membrane was used as the host cell in Hanks' solution. In this system, P32 put in a medium, from which non-radioactive phosphorus was removed previously, was highly incorporated into the virus particles and as a result as high as 8.22 specific activity in a sense of cpm/HA was obtainable. In purifying the labelled virus, adsorption to and elution from chicken red cells together with ultracentri-fugation was employed and a large amount of non-viral phosphorus was removed. The advantage of the technic described here will be in its reproducibility in preparing high specific virus. However, EID50/HA ratio was somewhat low with obtained specimens.
