Ezema Wilfred Sunday, Eze Didacus Chukwuemeka, Shoyinka Shodeinde Vincent Olu, Okoye John Osita Arinze
Department of Veterinary Pathology and Microbiology, University of Nigeria, Nsukka, Nigeria.
Trop Anim Health Prod. 2016 Dec;48(8):1703-1709. doi: 10.1007/s11250-016-1147-x. Epub 2016 Sep 19.
This project was undertaken to study the immunosuppressive capabilities of velogenic viscerotropic pathotype of Newcastle disease virus (VVNDV) infection in cockerels. Two hundred six-week-old cockerels were divided into four groups. Groups B/VUC and C/VC were vaccinated with LaSota in drinking water at 6 weeks of age. Groups C/VC and D/UC were challenged with VVNDV at 8 weeks of age. Three days post challenge (PC), the cockerels in group D/UC came down with clinical signs which included depression and greenish diarrhoea. Total mortality was 74.6 %. The C/VC cockerels showed no clinical signs. But both challenged groups showed significant weight loss, significant loss of total serum proteins, globulin and albumen (P < 0.05). These losses were more severe in the D/UC than in the C/VC. There was severe atrophy of the bursa, spleen and thymus in both groups. Histopathology showed severe necrosis and depletion of the lymphocytes in the three lymphoid organs. However, the lesions were more severe in the D/UC than in C/VC cockerels. On day 28, PC groups B/VUC, C/VIC and D/UIC were revaccinated with LaSota. The haemagglutination inhibition antibody response on days 35, 42 and 49 PC was very low in groups C/VIC and D/UIC when compared with B/VUC cockerels. These observations show that VVNDV infection both clinical and subclinical can cause immunosuppression and vaccine failure due to severe destruction of the lymphocytes in the lymphoid organs. This will be a serious problem for poultry production in those countries where the disease is enzootic.
本项目旨在研究新城疫病毒速发型嗜内脏型致病型（VVNDV）感染对公鸡的免疫抑制能力。200只6周龄公鸡被分为四组。B/VUC组和C/VC组在6周龄时通过饮水接种LaSota疫苗。C/VC组和D/UC组在8周龄时用VVNDV进行攻毒。攻毒后3天（PC），D/UC组的公鸡出现临床症状，包括精神沉郁和绿色腹泻。总死亡率为74.6%。C/VC组的公鸡未表现出临床症状。但两个攻毒组均出现显著体重减轻、血清总蛋白、球蛋白和白蛋白显著损失（P < 0.05）。这些损失在D/UC组比C/VC组更严重。两组的法氏囊、脾脏和胸腺均出现严重萎缩。组织病理学显示三个淋巴器官中的淋巴细胞严重坏死和耗竭。然而，D/UC组的病变比C/VC组的公鸡更严重。在第28天，PC组B/VUC、C/VIC和D/UIC用LaSota再次接种疫苗。与B/VUC组公鸡相比，C/VIC组和D/UIC组在攻毒后第35、42和49天的血凝抑制抗体反应非常低。这些观察结果表明，VVNDV感染无论是临床感染还是亚临床感染，都可导致免疫抑制和疫苗失败，原因是淋巴器官中的淋巴细胞受到严重破坏。在该病为地方流行性的国家，这将是家禽生产中的一个严重问题。
