Abstract
Summary
A chick-embryo-adapted canine distemper virus was propagated successfully for 64 passages in cultures of total chick-embryo tissues. As measured on the chorioallantoic membrane of live chick embryos, average virus titers of these passages ranged between 103.0 and 104.5/ml infected culture suspension. These titers are of the same order as those obtained with live-chick-embryo-grown virus. Identity of tissue-culture-grown agent with original CD virus employed was established by virus neutralization method and by ferret immunization. Effective freeze-dried vaccines were produced with different passage levels of tissue-culture-grown virus.
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