Exotic and Emerging Avian Disease Research Unit, Southeast Poultry Research Laboratory, U.S. National Poultry Research Center, Agricultural Research Service, USDA, 934 College Station Road, Athens, GA 30605, United States.
Exotic and Emerging Avian Disease Research Unit, Southeast Poultry Research Laboratory, U.S. National Poultry Research Center, Agricultural Research Service, USDA, 934 College Station Road, Athens, GA 30605, United States.
Vaccine. 2017 Nov 1;35(46):6345-6353. doi: 10.1016/j.vaccine.2017.04.042. Epub 2017 Apr 26.
From December 2014 to June 2015, a novel H5 Eurasian A/goose/Guangdong (Gs/GD) lineage clade 2.3.4.4 high pathogenicity avian influenza (HPAI) virus caused the largest animal health emergency in US history resulting in mortality or culling of greater than 48 million poultry. The outbreak renewed interest in developing intervention strategies, including vaccines, for these newly emergent HPAI viruses. In these studies, several existing H5 vaccines or vaccine seed strains with varying genetic relatedness (85-100%) to the 2.3.4.4 HPAI viruses were evaluated for protection in poultry. Chickens received a single dose of either an inactivated whole H5 AI vaccine, or a recombinant fowl poxvirus or turkey herpesvirus-vectored vaccines with H5 AI hemagglutinin gene inserts followed by challenge with either a U.S. wild bird H5N8 (A/gyrfalcon/Washington/40188-6/2014) or H5N2 (A/northern pintail/Washington/40964/2014) clade 2.3.4.4 isolate. Results indicate that most inactivated H5 vaccines provided 100% protection from lethal effects of H5N8 or H5N2 challenge. In contrast, the recombinant live vectored vaccines only provided partial protection which ranged from 40 to 70%. Inactivated vaccine groups, in general, had lower number of birds shedding virus and at lower virus titers then the recombinant vaccine groups. Interestingly, prechallenge antibody titers using the HPAI challenge viruses as antigen in heterologous vaccine groups were typically low (≤2 log), yet the majority of these birds survived challenge. Taken together, these studies suggest that existing vaccines when used in a single immunization strategy may not provide adequate protection in poultry against the 2.3.4.4 HPAI viruses. Updating the H5 hemagglutinin to be genetically closer to the outbreak virus and/or using a prime-boost strategy may be necessary for optimal protection.
从 2014 年 12 月到 2015 年 6 月，一种新型 H5 欧亚鹅/广东（Gs/GD）谱系 2.3.4.4 高致病性禽流感（HPAI）病毒引发了美国历史上最大的动物健康紧急事件，导致超过 4800 万只家禽死亡或被扑杀。此次疫情再次引发了人们对开发干预策略的兴趣，包括疫苗，以应对这些新出现的 HPAI 病毒。在这些研究中，几种现有的 H5 疫苗或疫苗种子株与 2.3.4.4 HPAI 病毒具有不同的遗传相关性（85-100%），用于评估家禽的保护效果。鸡只接受了单次剂量的灭活全 H5 AI 疫苗，或重组禽痘病毒或火鸡疱疹病毒载体疫苗，其中插入了 H5 AI 血凝素基因，然后用美国野生鸟类 H5N8（A/gyrfalcon/Washington/40188-6/2014）或 H5N2（A/northern pintail/Washington/40964/2014）谱系 2.3.4.4 分离株进行攻毒。结果表明，大多数灭活 H5 疫苗可提供 100%的保护，免受 H5N8 或 H5N2 攻毒的致死影响。相比之下，重组活载体疫苗仅提供 40%至 70%的部分保护。一般来说，灭活疫苗组的病毒载量和病毒脱落量低于重组疫苗组。有趣的是，在异源疫苗组中，使用 HPAI 攻毒病毒作为抗原的预攻毒抗体滴度通常较低（≤2 对数），但大多数这些鸡只仍能存活攻毒。综上所述，这些研究表明，现有的疫苗在单一免疫策略下使用时，可能无法为家禽提供针对 2.3.4.4 HPAI 病毒的充分保护。更新 H5 血凝素以使其与暴发病毒在遗传上更接近，或使用初免-加强策略，可能是获得最佳保护效果的必要条件。
