Vaccine R&D, Baxter BioScience, Biomedical Research Centre, Orth/Donau, Austria.
Vaccine. 2012 Jun 29;30(31):4625-31. doi: 10.1016/j.vaccine.2012.04.102. Epub 2012 May 10.
Influenza viruses of subtype A/H9N2 are enzootic in poultry across Asia and the Middle East and are considered to have pandemic potential. The development of new vaccine manufacturing technologies is a cornerstone of influenza pandemic preparedness.
A non-adjuvanted whole-virus H9N2 vaccine was developed using Vero cell culture manufacturing technology. The induction of hemagglutination inhibition (HI) and virus-neutralizing antibodies was assessed in CD1 mice and guinea pigs. A highly sensitive enzyme-linked lectin assay was used to investigate the induction of antibodies capable of inhibiting the enzymatic activity of the H9N2 neuraminidase. Protective efficacy against virus replication in the lung after challenge with the homologous virus was evaluated in BALB/c mice by a TCID(50) assay, and prevention of virus replication in the lung and associated pathology were evaluated by histology and immunohistochemistry. To investigate the ability of the vaccine to prevent severe disease, BALB/c mice were challenged with a highly virulent mouse-adapted H9N2 isolate which was generated by multiple lung-to-lung passage of wild-type virus.
The vaccine elicited high titers of functional H9N2-specific HA antibodies in both mice and guinea pigs, as determined by HI and virus neutralization assays. High titer H9N2-specific neuraminidase inhibiting (NAi) antibodies were also induced in both species. Vaccinated mice were protected from lung virus replication in a dose-dependent manner after challenge with the homologous H9N2 virus. Immunohistochemical analyses confirmed the lack of virus replication in the lung and an associated substantial reduction in lung pathology. Dose-dependent protection from severe weight loss was also provided after challenge with the highly virulent mouse-adapted H9N2 virus.
The induction of high titers of H9N2-specific HI, virus-neutralizing and NAi antibodies and dose-dependent protection from virus replication and severe disease in animal models suggest that the Vero cell culture-derived whole-virus vaccine will provide an effective intervention in the event of a H9N2 pandemic situation.
亚洲和中东地区的禽类中流行 A/H9N2 亚型流感病毒，被认为具有大流行的潜力。开发新的疫苗制造技术是流感大流行防范的基石。
使用 Vero 细胞培养制造技术开发了一种无佐剂的全病毒 H9N2 疫苗。在 CD1 小鼠和豚鼠中评估了血凝抑制（HI）和病毒中和抗体的诱导。使用高度敏感的酶联凝集素测定法来研究能够抑制 H9N2 神经氨酸酶酶活性的抗体的诱导。通过 TCID（50）测定法在 BALB/c 小鼠中评估了针对同源病毒攻击后肺中病毒复制的保护效力，并通过组织学和免疫组织化学评估了对肺和相关病理的病毒复制的预防。为了研究疫苗预防严重疾病的能力，用通过多次肺到肺传代野生型病毒生成的高致病性适应于小鼠的 H9N2 分离株对 BALB/c 小鼠进行了攻毒。
通过 HI 和病毒中和测定，疫苗在小鼠和豚鼠中均诱导了高滴度的功能性 H9N2 特异性 HA 抗体。在两种物种中也诱导了高滴度的 H9N2 特异性神经氨酸酶抑制（NAi）抗体。在同源 H9N2 病毒攻毒后，接种疫苗的小鼠以剂量依赖性方式防止了肺中的病毒复制。免疫组织化学分析证实了肺中没有病毒复制，并大大减少了肺病理。在接种高致病性适应于小鼠的 H9N2 病毒后，也提供了剂量依赖性的防止严重体重减轻的保护。
在动物模型中诱导了高滴度的 H9N2 特异性 HI、病毒中和和 NAi 抗体，以及剂量依赖性地防止了病毒复制和严重疾病，这表明 Vero 细胞培养衍生的全病毒疫苗将在 H9N2 大流行情况下提供有效的干预措施。
