Shalash Ahmed O, Becker Luke, Yang Jieru, Giacomin Paul, Pearson Mark, Hussein Waleed M, Loukas Alex, Skwarczynski Mariusz, Toth Istvan
School of Chemistry and Molecular Biosciences, The University of Queensland, St Lucia, QLD 4072, Australia.
Centre for Molecular Therapeutics, Australian Institute of Tropical Health and Medicine, James Cook University, Cairns, QLD 4878, Australia.
Vaccines (Basel). 2021 Sep 17;9(9):1034. doi: 10.3390/vaccines9091034.
Approximately 0.4 billion individuals worldwide are infected with hookworm. An effective vaccine is needed to not only improve the health of those affected and at high risk, but also to improve economic growth in disease-endemic areas. An ideal anti-hookworm therapeutic strategy for mass administration is a stable and orally administered vaccine. Oral vaccines are advantageous as they negate the need for trained medical staff for administration and do not require strict sterility conditions. Vaccination, therefore, can be carried out at a significantly reduced cost. One of the most promising current antigenic targets for hookworm vaccine development is the aspartic protease digestive enzyme (APR-1). Antibody-mediated neutralization of APR-1 deprives the worm of nourishment, leading to reduced worm burdens in vaccinated hosts. Previously, we demonstrated that, when incorporated into vaccine delivery systems, the APR-1-derived p3 epitope (TSLIAGPKAQVEAIQKYIGAEL) was able to greatly reduce worm burdens (≥90%) in BALB/c mice; however, multiple, large doses of the vaccine were required. Here, we investigated a variety of p3-antigen conjugates to optimize antigen delivery and establish immune response/protective efficacy relationships. We synthesized, purified, and characterized four p3 peptide-based vaccine candidates with: (a) lipidic (lipid core peptide (LCP)); (b) classical polymeric (polymethylacrylate (PMA)); and (c) novel polymeric (polyleucine in a branched or linear arrangement, BL or LL, respectively) groups as self-adjuvanting moieties. BL and LL induced the highest serum anti-p3 and anti-APR-1 IgG titers. Upon challenge with rodent hookworms, the highest significant reduction in worm burden was observed in mice immunized with LL. APR-1-specific serum IgG titers correlated with worm burden reduction. Thus, we provide the first vaccine-triggered immune response-protection relationship for hookworm infection.
全球约有4亿人感染钩虫。需要一种有效的疫苗，不仅要改善感染者和高危人群的健康状况，还要促进疾病流行地区的经济增长。一种理想的用于大规模接种的抗钩虫治疗策略是一种稳定的口服疫苗。口服疫苗具有优势，因为它们无需训练有素的医务人员进行接种，也不需要严格的无菌条件。因此，接种疫苗的成本可以大幅降低。目前钩虫疫苗开发中最有前景的抗原靶点之一是天冬氨酸蛋白酶消化酶（APR-1）。抗体介导的对APR-1的中和作用会使钩虫得不到营养，从而导致接种疫苗的宿主体内钩虫数量减少。此前，我们证明，当将源自APR-1的p3表位（TSLIAGPKAQVEAIQKYIGAEL）整合到疫苗递送系统中时，能够大幅降低BALB/c小鼠体内的钩虫数量（≥90%）；然而，需要多次大剂量接种该疫苗。在此，我们研究了多种p3抗原偶联物，以优化抗原递送并建立免疫反应/保护效力关系。我们合成、纯化并表征了四种基于p3肽的候选疫苗，它们分别带有：（a）脂质（脂质核心肽（LCP））；（b）经典聚合物（聚丙烯酸甲酯（PMA））；以及（c）新型聚合物（分别为支链或线性排列的聚亮氨酸，即BL或LL）基团作为自佐剂部分。BL和LL诱导产生的血清抗p3和抗APR-1 IgG抗体滴度最高。在用啮齿类钩虫进行攻毒后，在用LL免疫的小鼠中观察到钩虫数量的显著减少最为明显。APR-1特异性血清IgG抗体滴度与钩虫数量减少相关。因此，我们首次提供了针对钩虫感染的疫苗引发免疫反应与保护作用之间的关系。
