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Three gztups of laying hens with different HI titers i.e. Group A of 2,S6OxGroup B of l60..320x and Group C of 40x or lower, selected for this study in order to determine by the marker of HA titer, whether the ability of the propagation of Newcastle disease virus will be influenced or not when inoculated the prolagation totheir embryonating eggs. It has been known that potency of the killed vaccine prepared from the infected chicken embryo bodies seems to be closely related with the quantity of the virus in chicken embryos. In this study, the HI antibodies in chicks obtained maternally and the relationship between HI titer and Neutralization titer have been observed.
The results of this study may be summarized as follows:
1.The death time of 14-day-old chicken embryos inoculated with Newcastle disease virus apparently vaned with different HI titers in hens. The tests revealed that Group A2,560x or higher showed 72-96 hours or longer i.e. s ome of them were still alive when candled at 96 hours. It can be said the higher HI titer in hens the longer death time in chicken embryos.
2.As to the degree of H.A titer in l4days old eggs, either groups A of 2,560x orB of 160 320x showed highertiters and seemed no remarkable difference between them in aflantoic fluid, but apparently varied in embryo bodies. It can be said the higher HI titer in hens the lower HA titer in embryo bodies.Those embryos of Group C under 49x showed high titers both in embryo bodies and aflantoic fluid.
3. A study made on different age of embryos, it revealed the older embryos the longer death time, especially in Group A of 2,560x at l4days old of embryos, as about one third of the embryos tested were still alive even after 96 hours at the last checking. Those embryos of Group C under 40x, all the tested embryos of 8. 11 and l4days old died within 48 hours.
4.To 14-day -old embryos of HI titer 2.560x(Group A), there was apparent difference in HA. titer found in embryobodies, alsoonly little drops in that of S and 11-day-old eggs while all cases of the fluid showed high titers.
5.The HI titers in yolk orin small chicks obtained maternally were found as high as that of hens. Those higher HI antibodies in chicks obtained meterally will then gradually disappear at about 4-5 weeks of age.
6.From our experiments, it revealed the HI titer in serum is higher its Neutralization titer is also higher accordingly. A case of lOx of HI titer showed 2.9 of Neutralization titer and 5,120 x cases reached to as high as 6.8 of N titer.
NOTE: The outline of this paper was read before the 1964 Annual Meeting of the Taiwan Association of Animal Husbandry and Veterinary Medicine
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