ABSTRACT

Bacillus anthracis is an obligate pathogen and a causative agent of anthrax. Its major virulence factors are plasmid-coded; however, recent studies have revealed chromosome-encoded virulence factors, indicating that the current understanding of its virulence mechanism is elusive and needs further investigation. In this study, we established a silkworm (Bombyx mori) infection model of B. anthracis. We showed that silkworms were killed by B. anthracis Sterne and cured of the infection when administered with antibiotics. We quantitatively determined the lethal dose of the bacteria that kills 50% larvae and effective doses of antibiotics that cure 50% infected larvae. Furthermore, we demonstrated that B. anthracis mutants with disruption in virulence genes such as pagA, lef, and atxA had attenuated silkworm-killing ability and reduced colonization in silkworm hemolymph. The silkworm infection model established in this study can be utilized in large-scale infection experiments to identify novel virulence determinants and develop novel therapeutic options against B. anthracis infections.

 抽象的

炭疽芽孢杆菌是一种专性病原体，也是炭疽病的病原体。其主要毒力因子是质粒编码的；然而，最近的研究揭示了染色体编码的毒力因子，表明目前对其毒力机制的了解还难以捉摸，需要进一步研究。在本研究中，我们建立了家蚕（ Bombyx mori）炭疽杆菌感染模型。我们发现，蚕被炭疽杆菌杀死，并在给予抗生素后治愈了感染。我们定量确定了杀死 50% 幼虫的细菌致死剂量和治愈 50% 感染幼虫的抗生素有效剂量。此外，我们还证明，毒力基因（例如pagA、lef和atxA）被破坏的炭疽芽孢杆菌突变体削弱了蚕杀能力并减少了蚕血淋巴中的定植。本研究建立的蚕感染模型可用于大规模感染实验，以确定新的毒力决定因素并开发针对炭疽芽孢杆菌感染的新治疗方案。