流感病毒裂解疫苗佐剂对比：Alum-CpG肌肉注射与糖纳米颗粒鼻喷递送的免疫保护效果评价

Adjuvant comparison for influenza virus split vaccine：evaluation of immune protective efficacy between Alum-CpG and sugar-based lipid nanoparticles

摘要

目的：基于同一裂解疫苗抗原体系，比较铝佐剂-寡核苷酸（aluminum adjuvant-CpG oligodeoxynucleotide，Alum-CpG）复合佐剂肌肉注射与糖纳米颗粒（sugar-based lipid nanoparticle，SNP）鼻喷递送两种免疫策略的保护效果。方法：将8周龄BALB/c雌性小鼠随机分为Alum-CpG组、SNP组、仅肌注裂解疫苗的Split vaccine组及未免疫的对照组，共免疫2次，间隔14 d。加强免疫后第14天采集血清及鼻腔灌洗液（nasal lavage fluid，NLF），采用血凝抑制（hemagglutination inhibition，HI）试验和间接酶联免疫吸附试验检测抗体水平。随后以异源流感病毒A/Scotland/P2/2015（H1N1）进行攻毒，评价各组小鼠体重变化、存活率、肺组织病毒载量及肺部病理学改变。结果：在相同抗原剂量条件下，Alum-CpG组显著提高血清HI抗体效价，攻毒后小鼠存活率达100%，并显著降低肺组织流感病毒载量、减轻肺部炎性损伤。SNP组虽能诱导一定水平的HI抗体和分泌型免疫球蛋白A（secretory immunoglobulin A，sIgA）抗体并提供部分保护，但其HI抗体效价、存活率及病毒清除效果均低于Alum-CpG组及Split vaccine组，部分小鼠肺组织中仍可检测到较高水平的病毒复制。结论：Alum-CpG复合佐剂肌肉注射策略可显著提升裂解疫苗的免疫原性与保护效力，免疫增强作用优于SNP鼻喷递送；SNP作为鼻喷载体具有应用潜力，但需进一步优化其自身设计以提高保护效果。

Abstract

Objective：This study focused on the same split vaccine antigen system to compare the protective efficacy of two immunization strategies：intramuscular injection with aluminum adjuvant-CpG oligodeoxynucleotide（Alum-CpG）and intranasal delivery with sugar-based lipid nanoparticles（SNP）. Methods：Eight-week-old female BALB/c mice were randomly assigned into different experimental groups：Alum-CpG group，SNP group，intramuscular unadjuvanted split vaccine group，and unimmunized control group. All mice received two immunizations 14 days apart. On day 14 after the booster immunization，serum and nasal lavage fluid（NLF）were collected. Antibody levels were measured by hemagglutination inhibition（HI）assay and indirect enzyme-linked immunosorbent assay. Mice were then challenged with heterologous virus A/Scotland/P2/2015（H1N1）to evaluate body weight changes，survival rate，lung viral load，and pulmonary pathological changes. Results：Under equivalent antigen doses，intramuscular administration of the split vaccine adjuvanted with Alum-CpG significantly elevated serum HI antibody titers. Following viral challenge，mice in this group achieved a 100% survival rate，accompanied by marked reductions in lung viral loads and substantial alleviation of influenza-associated inflammatory lung pathology. Although the SNP group induced detectable serum HI antibodies and secretory IgA（sIgA）responses，and conferred partial protection against influenza virus challenge，its serum HI titers，survival rates，and viral clearance capacity were all inferior to those observed in the Alum-CpG group and the split vaccine group. Moreover，higher levels of viral replication were still detectable in the lung tissues of some mice in the SNP group. Conclusion：The intramuscular vaccination strategy employing Alum-CpG adjuvant markedly enhanced both the immunogenicity and protective efficacy of the split vaccine，demonstrating superior immune-enhancing effects compared to the intranasal SNP delivery. SNP have potential as an intranasal delivery platform，but their formulation design requires further optimization to improve protective efficacy.

关键词

流感病毒 / 裂解疫苗 / 铝佐剂 / 寡脱氧核苷酸 / 糖纳米颗粒

Key words

influenza virus / split vaccine / aluminum adjuvant / CpG oligodeoxynucleotide / sugar-based lipid nanoparticle

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基金资助

江苏省科技厅社会发展项目(BE2021756)

江苏省“双创人才”项目(JSSCRC2023555)