| 摘要 |
<p>An improved virus vaccine for canine distemper is obtained by passing canine distemper virus through live chick embryos for a sufficient number of passages to produce avirulence, inoculating the avirulent virus into a culture of chick embryo tissue and incubating and harvesting the resulting vaccine. Tissues from chick embryos of various ages may be used but tissues from nine day old embryos are preferred. Trypsinized chick embryo tissues are prepared in a conventional manner and are suspended in a growth medium fluid consisting of Earle's basal medium containing 0.5% lactalbumin hydrolysate and from 15 to 20% normal calf serum. Insulation was made with the 48th passage of modified canine distemper virus through live chick embryos. Incubation was for 7 days at 37 DEG C. The avirulent virus is passed serially through a plurality of chick embryo tissue cultures and then the harvested vaccine is freeze-dried. The resultant canine distemper virus is free from contamination with the tissue of the chick embryos.</p> |
