Chousalkar K K, Cheetham B F, Roberts J R
Animal Science, School of Environmental and Rural Science, University of New England, Armidale, New South Wales 2351, Australia.
Vaccine. 2009 Mar 4;27(10):1485-9. doi: 10.1016/j.vaccine.2009.01.012. Epub 2009 Jan 25.
In Australia, currently, all pullets reared for egg production are vaccinated with live attenuated strains of infectious bronchitis virus. Various vaccines and protocols to control this viral disease have been developed, although the severity of the disease varies from place to place and flock to flock. In the present trial, the effects of vaccine strains A3 and Vic S on the oviduct of laying hens were assessed by histopathology, electron microscopy, serology and also by determining the presence and persistence of viral RNA in the oviduct by real time PCR following the experimental infection. Birds were either unvaccinated or vaccinated with both A3 and Vic S and then mock-infected, challenged with the same attenuated strains, either A3 or Vic S. Some respiratory signs were observed, but were mild and short-lived. There was no drop in egg production in any of the groups. However, there was visual loss of shell colour in the unvaccinated hens challenged with the Vic S strain. Mild histopathology was recorded only in terms of lymphocyte infiltration and occasional submucosal oedema in the infundibulum and very mild gland dilatation in the magnum. Microscopic lesions were not recorded in the isthmus, tubular shell gland or shell gland pouch. Cilia loss was not observed in any region of the oviduct using scanning electron microscopy. Both the A3 and Vic S vaccine strains were detected in the oviduct of vaccinated and unvaccinated hens, mainly on the 12th day p.i. These results indicate that the A3 and Vic S strains replicate at a low level in the oviduct without causing significant damage and hence are safe for the oviduct.
在澳大利亚，目前所有用于产蛋的小母鸡都接种了传染性支气管炎病毒的减毒活疫苗株。尽管这种病毒性疾病的严重程度因地点和鸡群而异，但已经开发出了各种疫苗和方案来控制它。在本试验中，通过组织病理学、电子显微镜检查、血清学，以及在实验感染后通过实时聚合酶链反应测定输卵管中病毒RNA的存在和持续时间，评估了疫苗株A3和Vic S对蛋鸡输卵管的影响。鸡只要么未接种疫苗，要么同时接种A3和Vic S，然后进行假感染，用相同的减毒菌株A3或Vic S进行攻毒。观察到了一些呼吸道症状，但症状轻微且持续时间短。任何一组的产蛋量都没有下降。然而，用Vic S株攻毒的未接种疫苗的母鸡出现了蛋壳颜色明显变浅的情况。仅在漏斗部观察到轻度组织病理学变化，表现为淋巴细胞浸润和偶尔的黏膜下水肿，在膨大部观察到非常轻微的腺体扩张。峡部、管状蛋壳腺或蛋壳腺囊未记录到微观病变。使用扫描电子显微镜在输卵管的任何区域均未观察到纤毛缺失。在接种和未接种疫苗的母鸡的输卵管中均检测到A3和Vic S疫苗株，主要在感染后第12天检测到。这些结果表明，A3和Vic S株在输卵管中以低水平复制，不会造成显著损害，因此对输卵管是安全的。
