Scientific Support and Investigation Unit, Ceva-Phylaxia, Ceva Animal Health, Budapest 1107, Hungary.
Ceva Animal Health, Libourne 33500, France.
J Immunol Res. 2018 Nov 21;2018:3143189. doi: 10.1155/2018/3143189. eCollection 2018.
Outbreaks caused by the highly pathogenic avian influenza virus (HPAIV) H5N8 subtype clade 2.3.4.4 were first reported in 2014 in South Korea then spread very rapidly in Asia, to Europe, and for the first time, to North America. Efficacy of a recombinant HVT-AI (H5) vaccine (rHVT-H5) to provide clinical protection as well as to significantly reduce the shedding of an H5N8 challenge virus has already been demonstrated in SPF chickens. The aim of our studies was to test the efficacy of the same rHVT-H5 vaccine in controlling the transmission of a recent Hungarian HPAIV H5N8 challenge virus in commercial chickens. Broilers and layers were vaccinated at day old according to the manufacturer's recommendation and then challenged with a 2017 Hungarian HPAIV H5N8 (2.3.4.4b) isolate at 5 or 7 weeks of age, respectively. Evaluation of clinical protection, reduction of challenge virus shedding, and transmission to vaccinated contact birds was done on the basis of clinical signs/mortality, detection, and quantitation of challenge virus in oronasal and cloacal swabs (regularly between 1 and 14 days postchallenge). Measurement of seroconversion to AIV nucleoprotein was used as an indicator of infection and replication of challenge virus. Our results demonstrated that rHVT-H5 vaccination could prevent the development of clinical disease and suppress shedding very efficiently, resulting in the lack of challenge virus transmission to vaccinated contact chickens, regardless the type of birds. Single immunization with the tested rHVT-H5 vaccine proved to be effective to stop HPAIV H5N8 (2.3.4.4b) transmission within vaccinated poultry population under experimental conditions.
高致病性禽流感病毒（HPAIV）H5N8 亚型 2.3.4.4 分支引起的疫情于 2014 年在韩国首次报告，随后迅速在亚洲传播，并首次传播到北美。在 SPF 鸡中，重组 HVT-AI（H5）疫苗（rHVT-H5）在提供临床保护以及显著减少 H5N8 攻毒病毒的脱落方面的功效已得到证实。我们的研究旨在测试同一种 rHVT-H5 疫苗在控制最近匈牙利 HPAIV H5N8 攻毒病毒在商业鸡中的传播方面的功效。肉鸡和蛋鸡按照制造商的建议在 1 日龄时接种疫苗，然后分别在 5 或 7 周龄时用 2017 年匈牙利 HPAIV H5N8（2.3.4.4b）分离株进行攻毒。根据临床症状/死亡率、口鼻和泄殖腔拭子中攻毒病毒的检测和定量（定期在攻毒后 1 至 14 天之间）评估临床保护、攻毒病毒脱落减少和接种接触鸡的传播。抗 AIV 核蛋白的血清转化测量用作攻毒病毒感染和复制的指标。我们的结果表明，rHVT-H5 疫苗接种可以有效地预防临床疾病的发生并有效地抑制病毒脱落，从而阻止接种接触鸡传播攻毒病毒，无论鸡的类型如何。在实验条件下，用测试的 rHVT-H5 疫苗进行一次免疫接种即可有效阻止 HPAIV H5N8（2.3.4.4b）在接种禽类群体中的传播。
