Tabynov Kairat, Kuanyshbek Aidana, Zharmambet Kuantay, Yelchibayeva Leila, Karibayev Talgat, Berdikulov Maxat, Zhumadilova Zauresh, Tabynov Kaissar
International Center for Vaccinology, Kazakh National Agrarian Research University, Almaty, Kazakhstan; Central Reference Laboratory, M. Aikimbayev National Scientific Center for Especially Dangerous Infections, Almaty, Kazakhstan; T&TvaX LLC, Almaty, Kazakhstan.
National Collection of Deposited Strains, Almaty Branch of National Reference Veterinary Center, Almaty, Kazakhstan.
Virology. 2025 Sep;610:110601. doi: 10.1016/j.virol.2025.110601. Epub 2025 Jun 6.
Highly pathogenic avian influenza H5N8 (clade 2.3.4.4b) has caused devastating poultry outbreaks globally, including in Kazakhstan, underscoring the need for vaccines that protect birds and curb virus transmission. We evaluated the efficacy of three commercial H5 vaccines and an experimental homologous H5N8 vaccine in chickens.
Chickens received a single dose of each of the four vaccines (three commercial and one experimental), and antibody titers were measured over 4 weeks. At 30 days post-vaccination, birds were challenged intranasally with a virulent H5N8 strain and monitored for 10 days for survival and clinical signs. Virus titers in tracheal and cloacal swabs (days 1, 3, 5 post-challenge) measured shedding, and unvaccinated sentinel chickens were co-housed to assess transmission.
The homologous H5N8 vaccine and a closely related commercial vaccine elicited rapid, high antibody responses and conferred 100 % survival. In contrast, two vaccines with lower antigenic similarity to the challenge strain induced slower, lower immunity, resulting in 40-60 % mortality and higher virus shedding. Only the homologous vaccine markedly reduced viral shedding and limited transmission to contact birds (protecting 2 of 3 sentinel birds), whereas the other vaccines failed to prevent transmission.
An antigenically matched H5N8 vaccine with a potent adjuvant provided near-sterilizing immunity, preventing disease and significantly limiting viral shedding and transmission. These findings highlight the importance of using strain-matched vaccines in HPAI control strategies to avoid silent viral spread in vaccinated flocks.
高致病性禽流感H5N8（2.3.4.4b分支）已在全球范围内引发了毁灭性的家禽疫情，包括哈萨克斯坦，这凸显了开发能够保护禽类并遏制病毒传播的疫苗的必要性。我们评估了三种商用H5疫苗和一种实验性同源H5N8疫苗在鸡身上的效果。
给鸡分别接种四种疫苗（三种商用疫苗和一种实验性疫苗）中的一种，单剂量接种，在4周内测量抗体滴度。接种疫苗30天后，通过鼻腔接种强毒H5N8毒株对鸡进行攻毒，并监测10天，观察其存活情况和临床症状。检测气管和泄殖腔拭子中的病毒滴度（攻毒后第1、3、5天）以测定病毒排出情况，并将未接种疫苗的哨兵鸡与接种疫苗的鸡混养以评估病毒传播情况。
同源H5N8疫苗和一种密切相关的商用疫苗引发了快速、高水平的抗体反应，并使鸡的存活率达到100%。相比之下，另外两种与攻毒株抗原相似性较低的疫苗诱导的免疫反应较慢、水平较低，导致40%-60%的死亡率和更高的病毒排出量。只有同源疫苗显著减少了病毒排出，并限制了向接触鸡的传播（保护了3只哨兵鸡中的2只），而其他疫苗未能阻止病毒传播。
一种抗原匹配且含有强效佐剂的H5N8疫苗提供了近乎无菌的免疫力，预防了疾病，并显著限制了病毒排出和传播。这些发现凸显了在高致病性禽流感防控策略中使用毒株匹配疫苗以避免疫苗接种鸡群中病毒无声传播的重要性。
