Highly pathogenic influenza H7N9 viruses that emerged in the fifth wave of H7N9 outbreak pose a risk to human health. The World Health Organization has updated the candidate vaccine viruses for H7N9 viruses recently. In this study, we evaluated the immune response to an updated H7N9 candidate vaccine virus, which derived from the highly pathogenic A/Guangdong/17SF003/2016 (GD/16) in mice and rhesus macaques. GD/16 vaccination elicited robust neutralizing, virus-specific immunoglobulin G antibodies and effective protection, but poor hemagglutination inhibition antibody titers. Furthermore, mouse and rhesus macaque serum raised against the previous H7N9 CVV A/Anhui/1/2013 (AH/13) were tested for its cross-reactivity to GD/16 virus. We found that although AH/13-immune serum has poor hemagglutination inhibition reactivity against GD/16 virus, AH/13 elicit efficient cross-neutralizing antibodies and in vivo protection against GD/16. Further studies showed that the hemagglutinin of GD/16 has strong receptor binding avidity, which might be associated with the decreased hemagglutination inhibition assay sensitivity. This study underscores the point that receptor binding avidity should be taken into account when performing quantitative interpretation of hemagglutination inhibition data. A combination of multiple serological assays is required for accurate vaccine evaluation and antigenic analysis of influenza viruses.

中文翻译：

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评估来自第五次浪潮的H7N9候选疫苗病毒的免疫应答A / Guangdong / 17SF003 / 2016。

在第五次H7N9爆发中出现的高致病性H7N9流感病毒对人类健康构成威胁。世界卫生组织最近为H7N9病毒更新了候选疫苗病毒。在这项研究中，我们评估了对更新的H7N9候选疫苗病毒的免疫应答，该病毒源自小鼠和恒河猴中的高致病性A / Guangdong / 17SF003 / 2016（GD / 16）。GD / 16疫苗接种可产生强大的中和作用，病毒特异性免疫球蛋白G抗体和有效的保护作用，但血凝抑制抗体效价却很差。此外，测试了针对先前H7N9 CVV A / Anhui / 1/2013（AH / 13）的小鼠和恒河猴猕猴血清与GD / 16病毒的交叉反应性。我们发现，虽然AH / 13免疫血清对GD / 16病毒的血细胞凝集抑制反应性较差，AH / 13引发有效的交叉中和抗体，并对GD / 16进行体内保护。进一步的研究表明，GD / 16的血凝素具有很强的受体结合亲和力，这可能与降低的血凝抑制测定灵敏度有关。这项研究强调了在定量解释血凝抑制数据时应考虑受体结合亲和力的观点。准确的疫苗评估和流感病毒的抗原分析需要多种血清学检测的组合。这项研究强调了在定量解释血凝抑制数据时应考虑受体结合亲和力的观点。准确的疫苗评估和流感病毒的抗原分析需要多种血清学检测的组合。这项研究强调了在定量解释血凝抑制数据时应考虑受体结合亲和力的观点。准确的疫苗评估和流感病毒的抗原分析需要多种血清学检测的组合。