Mirzaiee K, Shoushtari A, Bokaie S, Fallah Mehrabadi M H, Peighambari S M
Department of Food Hygiene and Quality Control, Faculty of Veterinary Medicine, University of Tehran, Tehran, Iran.
Department of Poultry Diseases, Razi Vaccine and Serum Research Institute, Agricultural Research, Education and Extension Organization (AREEO), Karaj, Iran.
Arch Razi Inst. 2020 Mar;75(1):9-16. doi: 10.22092/ari.2018.120089.1183. Epub 2020 Mar 1.
Avian influenza virus (AIV) H9N2 is endemic in Iran and its large-scale circulation in the poultry industry of the country is devastating. This virus was first reported in the industrial poultry populations of Iran in July 1998. Some of the published studies showed that inactivated avian influenza (AI) vaccines are capable of inducing an immune response and providing protection against morbidity and mortality in different countries (Vasfi et al., 2002; Tavakkoli et al., 2011). Low pathogenicity avian influenza subtype H9N2 virus has been reported to have a zoonotic potential and widespread distribution in Iran. Therefore, water-in-oil emulsion vaccines are employed to control the disease in chickens (Nili and Asasi, 2003). This cohort study was conducted during July 2016-November 2017 in broiler chicken farms of Qazvin province, Iran to investigate the serological change trends in broiler chickens in this region. Level of immunity against the H9N2 virus was evaluated by hemagglutination inhibition assay. Fifteen farms out of thirty enrolled units used AI H9N2 killed vaccines. The minimum of mean antibody titers (MATs) was 4.54-2.42 and the maximum of MATs was 4.54+2.42 on day 3. In addition, the minimum and maximum MATs on day 50 were 0.4-0.64 and 0.4+0.064, respectively. The transfer rate of H9N2 AIV antibodies from the serum of breeders to the serum of chickens was calculated as 60.35% in our study. A significant difference was revealed between the maternal mean antibody titers (MMATs) and the MATs on day 3 (P<0.001). In addition, the difference between the MATs on day 3 and the MATs on day 10 was found to be significant (P<0.01). Moreover, MATs were significantly different between the vaccinated and unvaccinated herds on day 40 (P<0.05), while no significant difference was observed on days 3, 10, 20, and 30 (P>0.05). According to the results of this study, antibody titers in the vaccinated farms did not reach the protective level until the end of the rearing period. Most of the unvaccinated herds experienced a spurt in antibody titers due to exposure to the virus. Consequently, biosecurity measures must be implemented more seriously and strictly in broiler farms.
H9N2亚型禽流感病毒（AIV）在伊朗呈地方流行性，其在该国家禽业中的大规模传播具有毁灭性。该病毒于1998年7月首次在伊朗的工业化家禽群体中被报道。一些已发表的研究表明，灭活禽流感（AI）疫苗能够在不同国家诱导免疫反应并预防发病和死亡（瓦斯菲等人，2002年；塔瓦科利等人，2011年）。据报道，低致病性禽流感H9N2亚型病毒在伊朗具有人畜共患病潜力且分布广泛。因此，采用油包水乳化疫苗来控制鸡群中的疾病（尼利和阿萨西，2003年）。这项队列研究于2016年7月至2017年11月在伊朗加兹温省的肉鸡养殖场进行，以调查该地区肉鸡的血清学变化趋势。通过血凝抑制试验评估针对H9N2病毒的免疫水平。在纳入研究的30个单位中，有15个养殖场使用了H9N2禽流感灭活疫苗。在第3天，平均抗体滴度（MATs）的最小值为4.54 - 2.42，最大值为4.54 + 2.42。此外，在第50天，MATs的最小值和最大值分别为0.4 - 0.64和0.4 + 0.064。在我们的研究中，H9N2 AIV抗体从种鸡血清转移到雏鸡血清的转移率计算为60.35%。种鸡平均抗体滴度（MMATs）与第3天的MATs之间存在显著差异（P＜0.001）。此外，发现第3天的MATs与第10天的MATs之间存在显著差异（P＜0.01）。而且，在第40天，接种疫苗和未接种疫苗的鸡群之间的MATs存在显著差异（P＜0.05），而在第3天、第10天、第20天和第30天未观察到显著差异（P＞0.05）。根据这项研究的结果，在饲养期结束前，接种疫苗养殖场的抗体滴度未达到保护水平。大多数未接种疫苗的鸡群由于接触病毒，抗体滴度出现激增。因此，必须在肉鸡养殖场更认真、严格地实施生物安全措施。
