Background

Vaccination is the most effective approach to prevent infection with highly pathogenic avian influenza (HPAI). Adjuvants are often used to induce effective immune responses and overcome the immunological weakness of recombinant HPAI antigens. Given the logistical challenges of immunization to HPAI during pandemic situations, vaccines administered via the intramuscular (I.M.) route would be of value.

Methods

A new formulation of nanoemulsion adjuvant (NE02) suitable for I.M. vaccination was developed. This NE02 was evaluated alone and in combination with CpG to develop H5 immune responses in mouse and ferret models. Measures of recombinant H5 (rH5) specific immunity evaluated included serum IgG and IgG subclasses, bronchoalveolar lavage fluid IgA, and cytokines. The activation of NF-kB was also analyzed. The efficacy of the vaccine was assessed by performing hemagglutination inhibition (HAI), virus neutralization (VN) assays, and viral challenges in ferrets.

Results

I.M. vaccination with rH5-NE02 significantly increased rH5-specific IgG and protected ferrets in the viral challenge model providing complete protection and sterile immunity in all animals tested. Combining NE02 and CpG produced accelerated antibody responses and this was accompanied by an elevation of IFN-γ and IL-17 responses and the downregulation of IL-5. The combination also caused a synergistic effect on NF-kB activation. In immunized ferrets after viral challenge, the rH5-NE02 + CpG vaccine via I.M. achieved at least 75% and 88% seroconversion of HAI and VN antibody responses, respectively, and improved body temperature stabilization and weight loss over NE02 alone.

Conclusions

The I.M. injection of NE02 adjuvanted rH5 elicits strong and broad immune responses against H5 antigens and effectively protects animals from lethal H5 challenge. Combining this adjuvant with CpG enhanced immune responses and provided improvements in outcomes to viral challenge in ferrets. The results suggest that combinations of adjuvants may be useful to enhance H5 immune responses and improve protection against influenza infection.

中文翻译：

---

肌内疫苗佐剂，纳米乳剂和CpG的新型组合可产生针对甲型流感病毒的有效免疫反应

背景

接种疫苗是预防高致病性禽流感（HPAI）感染的最有效方法。佐剂通常用于诱导有效的免疫反应并克服重组HPAI抗原的免疫学缺陷。鉴于在大流行情况下对高致病性禽流感免疫的后勤挑战，通过肌内（IM）途径施用的疫苗将具有价值。

方法

开发了适用于IM疫苗接种的新型纳米乳剂佐剂（NE02）。单独和与CpG一起评估此NE02在小鼠和雪貂模型中产生H5免疫应答。评估的重组H5（rH5）特异性免疫力包括血清IgG和IgG亚类，支气管肺泡灌洗液IgA和细胞因子。还分析了NF-kB的活化。通过进行血凝抑制（HAI），病毒中和（VN）分析和在雪貂中进行病毒攻击来评估疫苗的功效。

结果

用rH5-NE02进行IM疫苗接种可在病毒激发模型中显着增加rH5特异性IgG和受保护的雪貂，从而为所有测试的动物提供完全的保护和无菌免疫。NE02和CpG的结合产生了加速的抗体应答，并伴随着IFN-γ和IL-17应答的升高以及IL-5的下调。该组合还对NF-κB活化产生协同作用。在病毒攻击后的免疫雪貂中，通过IM的rH5-NE02 + CpG疫苗分别实现了HAI和VN抗体应答的至少75％和88％的血清转化，并且比单独使用NE02改善了体温稳定性和体重减轻。

结论

IM02佐剂的rH5的IM注射引起针对H5抗原的强而广泛的免疫应答，并有效地保护动物免受致命的H5攻击。将这种佐剂与CpG结合使用可增强免疫反应，并改善雪貂病毒攻击的结果。结果表明佐剂组合可能对增强H5免疫反应和改善抵抗流感感染的保护有用。