Table_1_Dry and liquid formulations of IBT-V02, a novel multi-component toxoid vaccine, are effective against Staphylococcus aureus isolates from low-to-middle income countries.docx

Staphylococcus aureus is the leading cause of skin and soft tissue infections (SSTIs) in the U.S. as well as more serious invasive diseases, including bacteremia, sepsis, endocarditis, surgical site infections, osteomyelitis, and pneumonia. These infections are exacerbated by the emergence of antibiotic-resistant clinical isolates such as methicillin-resistant S. aureus (MRSA), highlighting the need for alternatives to antibiotics to treat bacterial infections. We have previously developed a multi-component toxoid vaccine (IBT-V02) in a liquid formulation with efficacy against multiple strains of Staphylococcus aureus prevalent in the industrialized world. However, liquid vaccine formulations are not compatible with the paucity of cold chain storage infrastructure in many low-to-middle income countries (LMICs). Furthermore, whether our IBT-V02 vaccine formulations are protective against S. aureus isolates from LMICs is unknown. To overcome these limitations, we developed lyophilized and spray freeze-dried formulations of IBT-V02 vaccine and demonstrated that both formulations had comparable biophysical attributes as the liquid formulation, including similar levels of toxin neutralizing antibodies and protective efficacy against MRSA infections in murine and rabbit models. To enhance the relevancy of our findings, we then performed a multi-dimensional screen of 83 S. aureus clinical isolates from LMICs (e.g., Democratic Republic of Congo, Palestine, and Cambodia) to rationally down-select strains to test in our in vivo models based on broad expression of IBT-V02 targets (i.e., pore-forming toxins and superantigens). IBT-V02 polyclonal antisera effectively neutralized toxins produced by the S. aureus clinical isolates from LMICs. Notably, the lyophilized IBT-V02 formulation exhibited significant in vivo efficacy in various preclinical infection models against the S. aureus clinical isolates from LMICs, which was comparable to our liquid formulation. Collectively, our findings suggested that lyophilization is an effective alternative to liquid vaccine formulations of our IBT-V02 vaccine against S. aureus infections, which has important implications for protection from S. aureus isolates from LMICs.

金黄色葡萄球菌（Staphylococcus aureus）是美国皮肤和软组织感染（skin and soft tissue infections, SSTIs）以及菌血症、败血症、心内膜炎、手术部位感染、骨髓炎与肺炎等更严重侵袭性疾病的首要致病菌。耐甲氧西林金黄色葡萄球菌（methicillin-resistant S. aureus, MRSA）这类耐药临床分离株的出现加剧了此类感染，凸显了开发抗菌治疗替代方案的迫切需求。本研究团队此前开发了一款多组分类毒素疫苗IBT-V02，采用液态制剂形式，对工业化国家流行的多株金黄色葡萄球菌具有保护效力。然而，液态疫苗制剂无法适配众多中低收入国家（low-to-middle income countries, LMICs）冷链储存基础设施匮乏的现状。此外，本研究团队开发的IBT-V02疫苗制剂是否能够有效抵御中低收入国家来源的金黄色葡萄球菌分离株，目前尚不明确。为克服上述局限，本研究团队开发了IBT-V02疫苗的冻干与喷雾冷冻干燥制剂，并证实两种制剂与液态制剂具备相当的生物物理特性，包括相似水平的毒素中和抗体，以及在小鼠与兔模型中对抗MRSA感染的保护效力。为提升研究结果的相关性，本研究团队对83株来自中低收入国家（如刚果民主共和国、巴勒斯坦、柬埔寨）的金黄色葡萄球菌临床分离株开展多维度筛选，基于IBT-V02靶点（即成孔毒素与超抗原）的广泛表达情况，理性筛选出可用于体内模型测试的菌株。IBT-V02多克隆抗血清可有效中和中低收入国家来源的金黄色葡萄球菌临床分离株所产生的毒素。值得注意的是，冻干IBT-V02制剂在多种临床前感染模型中，对中低收入国家来源的金黄色葡萄球菌临床分离株展现出显著的体内保护效力，其效果与液态制剂相当。综上，本研究结果表明，冻干工艺可作为IBT-V02疫苗液态制剂的有效替代方案，用于对抗金黄色葡萄球菌感染，这对中低收入国家的金黄色葡萄球菌感染防控具有重要意义。