<i>Galleria mellonella</i> as an infection model for the virulent <i>Mycobacterium tuberculosis</i> H37Rv

Tuberculosis (TB), caused by <i>Mycobacterium tuberculosis</i> (<i>MTB</i>), is a leading cause of infectious disease mortality. Animal infection models have contributed substantially to our understanding of TB, yet their biological and non-biological limitations are a research bottleneck. There is a need for more ethically acceptable, economical, and reproducible TB infection models capable of mimicking key aspects of disease. Here, we demonstrate and present a basic description of how <i>Galleria mellonella</i> (the greater wax moth, <i>Gm</i>) larvae can be used as a low cost, rapid, and ethically more acceptable model for TB research. This is the first study to infect <i>Gm</i> with the fully virulent <i>MTB</i> H37Rv, the most widely used strain in research. Infection of <i>Gm</i> with <i>MTB</i> resulted in a symptomatic lethal infection, the virulence of which differed from both attenuated <i>Mycobacterium bovis</i> BCG and auxotrophic <i>MTB</i> strains. The <i>Gm-MTB</i> model can also be used for anti-TB drug screening, although CFU enumeration from <i>Gm</i> is necessary for confirmation of mycobacterial load reducing activity of the tested compound. Furthermore, comparative virulence of <i>MTB</i> isogenic mutants can be determined in <i>Gm</i>. However, comparison of mutant phenotypes in <i>Gm</i> against conventional models must consider the limitations of innate immunity. Our findings indicate that <i>Gm</i> will be a practical, valuable, and advantageous additional model to be used alongside existing models to advance tuberculosis research.

由结核分枝杆菌（Mycobacterium tuberculosis, MTB）引发的结核病（Tuberculosis, TB）是感染性疾病致死的主要病因。动物感染模型对我们深入理解结核病机制做出了重要贡献，但其生物学与非生物学局限成为了相关研究的瓶颈。当前亟需更符合伦理规范、成本低廉且可重复的结核病感染模型，以模拟该病的关键病理特征。本研究验证并阐述了大蜡螟（Galleria mellonella, 简称Gm）幼虫作为低成本、快速且伦理接受度更高的结核病研究模型的应用方式。本研究是首个使用科研领域应用最广泛的强毒力菌株MTB H37Rv感染Gm的工作。MTB感染Gm可引发具有典型症状的致死性感染，其毒力与减毒牛分枝杆菌卡介苗（Mycobacterium bovis BCG）及营养缺陷型MTB菌株均存在差异。Gm-MTB模型还可用于抗结核药物筛选，不过需通过对Gm进行菌落形成单位（Colony-Forming Units, CFU）计数，以验证受试化合物的分枝杆菌载量降低活性。此外，可在Gm中评估MTB同源突变株的相对毒力。但将Gm中突变株的表型与传统模型进行比较时，需考虑其固有免疫的局限性。本研究结果表明，Gm可作为一种实用、极具价值且优势显著的补充模型，与现有模型协同用于推动结核病研究的进展。