초록
실용 산란계 병아리에 대해서 시중에서 유통되고 있는 B$_1$생독 뉴캣슬병백신의 효능을 접종방법과 접종횟수를 달리하여 비교하였다. 실용산란계 372수를 93수씩 4군으로 나눈 후 3군에 대해서는 각각 음수. 점안, 분무방법으로 28일령까지 3회에 걸쳐 백신을 접종하였고 나머지 1군은 백신을 접종하지 않은 대조군으로 하였다. 매회 백신접종 2준 4주 후에 강독 바이러스로 공격접종하여 방어율을 조사하고 2주 간격으로 채혈하여, 혈구응집억제(HI) 항체가를 조차하였다. 방어율은 1일령에 1회 접종하는 것보다 2회 또는 3회 접종하는 것이 높았으나 2회. 3회간에는 큰 차이가 없었다. 접종방법간에는 분무방법이 2회 이상 접종할 경우 방어율이 높았으며 다음은 점안, 음수 순이었다. 백신을 2회 또는 3회 접종하여도 HI항체가는 대조군에 비해 크게 상승하지 않았다. 전반적으로 방어율이 낮은 것은 백신의 역가가 낮기 때문으로 생각되었다. 공격접종 후 뉴캣슬병 임상증상은 84% 이상에서 원기 및 식욕저하와 기면을 보였고 27%에서 설사, 15%에서 호홉곤란, 10%에서는 사경을 보였다. 부견소견상 출혈반은 십이지장(51%), 기관(36%), 회장(13%), 맹장편도(11%), 선위(10%) 순으로 관찰되었다.
The immune responses of commercial layer chickens against Newcastle disease (ND) were compared among different administration methods and times of vaccination during 4 weeks of age. A total of 372 day-old chickens were devided into 4 groups of 93 birds each. Each of 3 groups was received a commercially available B$_1$ live vaccine via drinking water, eye instillation or spray method at one, 14 and 28 days of age. One group was used as an unvaccinated control. At two and 4 weeks after each time of vaccination, 15 birds from each group were challenged with virulent ND virus at the dose of 10$^{5}$ EID$_{50}$ per bird to examine the pretection rate. Ten to 15 birds from each group were bled at two weeks intervals from day old to 8 weeks of age to determine hemagglutination inhibition antibody titer. The protection rate was generally low regardless of the times of vaccination although two or more times vaccination gave higher protection than once vaccination. The low protection was considered due to low titer of the vaccine used since the vaccine titer was less than 10$^{2.5}$ EID$_{50}$ per bird. Spray method gave better protection compared to eye instillation of drinking water method which resulted in lowest response. When birds were challenged majority showed clinical signs on ND between 3 and 6 days after challenge. Death occured one or two days after onset of symptoms. Major clinical signs observed were depression (96%), drowsy(90%), anorexia (84%), diarrhoea (29%), difficult breath (15%) and torticollis (10%). Hemorrhagic lesions on post mortem were seen in duodenum (51%), trachea(36%), illeum (13%), ceacal tonsil (11%), proventriculus (10%) and some other organs. When birds were challenged majority showed clinical signs on ND between 3 and 6 days after challenge. Death occured one or two days after onset of symptoms. Major clinical signs observed were depression (96%), drowsy(90%), anorexia (84%), diarrhoea (29%), difficult breath (15%) and torticollis (10%). Hemorrhagic lesions on post mortem were seen in duodenum (51%), trachea(35%), illeum (13%), ceacal tonsil (11%), proventriculus (10%) and some other organs.