Department of Pathology, University of Veterinary and Animal Sciences, Lahore-Pakistan.
Department of Parasitology, University of Veterinary and Animal Sciences, Lahore-Pakistan.
J Biol Regul Homeost Agents. 2018 Nov-Dec;32(6):1545-1549.
TThe efficacy of the two commonly used commercial vaccines for Newcastle disease (ND) and low path avian influenza (LPAI) H9N2 were evaluated against field virus in broiler chicks. One hundred one-dayold commercial broiler chicks were divided into four groups (A to D) with an equal number of birds per group. Group A and B were vaccinated against H9N2 and NDV, respectively, at day 7 of age while group C served as positive infected control for H9N2 and group D for NDV. Serum samples from birds in all groups were tested for presence of antibodies against H9N2 and NDV at day 21 of age. Subsequently, on day 28 of age, groups A and C were challenged with the field strain of H9N2 virus, and Group B and D with NDV. Birds were monitored for a period of 2 weeks for development of any clinical signs and mortality. The geometric mean titer were high in groups A (4.90) and B (7.3), and low in the unvaccinated groups C (0.7) and D (1.1). The highest and lowest value of H9N2 antibody titer detected through ELISA were 1.498 and 0.502, respectively. The S/P ratios greater than 0.5 were considered positive. The highest and lowest value for NDV antibody titer detected through ELISA were 783 and 882, respectively. Serum samples with titer greater than 396 were considered positive and indicated vaccination or other exposure to NDV. On histological examination severe congestion, necrosis, degeneration, hemorrhages and leukocyte infiltration were observed in intestine, lungs, trachea and bursa of Fabricius of the non-vaccinated group post-infection. Mild tissues changes were observed in the vaccinated group. It can be concluded from the findings that the commonly used commercial vaccines may provide effective protection against the circulating H9N2 and ND virus in broiler birds by producing protective antibody titer.
本研究评估了两种常用于预防新城疫（ND）和低致病性禽流感（LPAI）H9N2 的商业疫苗在肉鸡中的效力。将 101 日龄的商业肉鸡分为 4 组（A 至 D），每组有相同数量的鸡。A 组和 B 组分别于 7 日龄接种 H9N2 和 NDV 疫苗，C 组为 H9N2 阳性感染对照，D 组为 NDV 阳性感染对照。所有组的鸡血清样本于 21 日龄时检测 H9N2 和 NDV 抗体。随后，于 28 日龄时，A 组和 C 组用 H9N2 野毒株攻毒，B 组和 D 组用 NDV 攻毒。鸡群监测了 2 周，观察有无临床症状和死亡率。A 组（4.90）和 B 组（7.3）的几何平均滴度较高，而未接种疫苗的 C 组（0.7）和 D 组（1.1）的滴度较低。通过 ELISA 检测到的 H9N2 抗体滴度最高值和最低值分别为 1.498 和 0.502。S/P 比值大于 0.5 被认为是阳性。通过 ELISA 检测到的 NDV 抗体滴度最高值和最低值分别为 783 和 882。滴度大于 396 的血清样本被认为是阳性，表明接种了 NDV 疫苗或曾接触过 NDV。组织学检查发现，感染后未接种疫苗组的鸡肠道、肺、气管和法氏囊出现严重充血、坏死、变性、出血和白细胞浸润，接种疫苗组的组织变化较轻。从研究结果可以得出结论，常用的商业疫苗可通过产生保护性抗体滴度，为肉鸡提供针对流行的 H9N2 和 ND 病毒的有效保护。
