Aminzadeh Aria, Hilgers Luuk, Paul Platenburg Peter, Riou Mickaël, Perrot Noémie, Rossignol Christelle, Cauty Axel, Barc Céline, Jørgensen René
Proxi Biotech ApS, Egeskellet 6, 2000 Frederiksberg, Denmark; Department of Science and Environment, University of Roskilde, 4000 Roskilde, Denmark.
LiteVax BV, Akkersestraat 50, 4061BJ Ophemert, the Netherlands.
Vaccine. 2024 Mar 7;42(7):1582-1592. doi: 10.1016/j.vaccine.2024.01.076. Epub 2024 Feb 9.
Clostridioides difficile infection (CDI) is a serious healthcare-associated disease, causing symptoms such as diarrhea and pseudomembranous colitis. The major virulence factors responsible for the disease symptoms are two secreted cytotoxic proteins, TcdA and TcdB. A parenteral vaccine based on formaldehyde-inactivated TcdA and TcdB supplemented with alum adjuvant, has previously been investigated in humans but resulted in an insufficient immune response. In search for an improved response, we investigated a novel toxin inactivation method and a novel, potent adjuvant. Inactivation of toxins by metal-catalyzed oxidation (MCO) was previously shown to preserve neutralizing epitopes and to annihilate reversion to toxicity. The immunogenicity and safety of TcdA and TcdB inactivated by MCO and combined with a novel carbohydrate fatty acid monosulphate ester-based (CMS) adjuvant were investigated in rabbits. Two or three intramuscular immunizations generated high serum IgG and neutralizing antibody titers against both toxins. The CMS adjuvant increased antibody responses to both toxins while an alum adjuvant control was effective only against TcdA. Systemic safety was evaluated by monitoring body weight, body temperature, and analysis of red and white blood cell counts shortly after immunization. Local safety was assessed by histopathologic examination of the injection site at the end of the study. Body weight gain was constant in all groups. Body temperature increased up to 1 ˚C one day after the first immunization but less after the second or third immunization. White blood cell counts, and percentage of neutrophils increased one day after immunization with CMS-adjuvanted vaccines, but not with alum. Histopathology of the injection sites 42 days after the last injection did not reveal any abnormal tissue reactions. From this study, we conclude that TcdA and TcdB inactivated by MCO and combined with CMS adjuvant demonstrated promising immunogenicity and safety in rabbits and could be a candidate for a vaccine against CDI.
艰难梭菌感染（CDI）是一种严重的医疗保健相关疾病，可引起腹泻和假膜性结肠炎等症状。导致这些疾病症状的主要毒力因子是两种分泌型细胞毒素蛋白，即TcdA和TcdB。此前曾在人体中研究过一种基于甲醛灭活的TcdA和TcdB并添加明矾佐剂的肠胃外疫苗，但免疫反应不足。为了寻求更好的反应，我们研究了一种新型毒素灭活方法和一种新型强效佐剂。此前研究表明，金属催化氧化（MCO）使毒素失活可保留中和表位并消除毒性逆转。我们在兔子身上研究了经MCO灭活并与一种新型基于碳水化合物脂肪酸单硫酸酯（CMS）的佐剂联合使用的TcdA和TcdB的免疫原性和安全性。两次或三次肌肉注射产生了针对两种毒素的高血清IgG和中和抗体滴度。CMS佐剂增强了对两种毒素的抗体反应，而明矾佐剂对照组仅对TcdA有效。通过在免疫后不久监测体重、体温以及分析红细胞和白细胞计数来评估全身安全性。在研究结束时通过对注射部位进行组织病理学检查来评估局部安全性。所有组的体重增加均保持恒定。首次免疫后一天体温升高至1℃，但第二次或第三次免疫后升高幅度较小。用CMS佐剂疫苗免疫后一天白细胞计数和中性粒细胞百分比增加，但明矾佐剂疫苗免疫后未增加。最后一次注射后42天注射部位的组织病理学检查未发现任何异常组织反应。从这项研究中，我们得出结论，经MCO灭活并与CMS佐剂联合使用的TcdA和TcdB在兔子身上表现出有前景的免疫原性和安全性，可能是一种抗CDI疫苗的候选物。
