Department of Microbiology and Immunology, McGill University, Montreal, QC, H3A 2B4, Canada.
Division of Emerging and Transfusion Transmitted Diseases, CBER, FDA, Silver Spring, MD, 20993, USA.
Nat Commun. 2020 Jul 10;11(1):3461. doi: 10.1038/s41467-020-17154-z.
Leishmaniasis is a neglected tropical disease caused by Leishmania protozoa transmitted by infected sand flies. Vaccination through leishmanization with live Leishmania major has been used successfully but is no longer practiced because it resulted in occasional skin lesions. A second generation leishmanization is described here using a CRISPR genome edited L. major strain (LmCen). Notably, LmCen is a genetically engineered centrin gene knock-out mutant strain that is antibiotic resistant marker free and does not have detectable off-target mutations. Mice immunized with LmCen have no visible lesions following challenge with L. major-infected sand flies, while non-immunized animals develop large and progressive lesions with a 2-log fold higher parasite burden. LmCen immunization results in protection and an immune response comparable to leishmanization. LmCen is safe since it is unable to cause disease in immunocompromised mice, induces robust host protection against vector sand fly challenge and because it is marker free, can be advanced to human vaccine trials.
利什曼病是一种由利什曼原虫引起的热带病，通过受感染的沙蝇传播。通过用活的利什曼原虫进行利什曼化疫苗接种已被成功应用，但现已不再使用，因为它会偶尔导致皮肤损伤。本文描述了一种第二代利什曼化，使用了经过 CRISPR 基因组编辑的 L. major 菌株（LmCen）。值得注意的是，LmCen 是一种经过基因工程改造的中心体基因敲除突变株，它没有抗生素抗性标记，也没有可检测的脱靶突变。用 LmCen 免疫的小鼠在受到感染了 L. major 的沙蝇的挑战后没有可见的病变，而未免疫的动物则会发展出大而进行性的病变，寄生虫负担高出 2 个对数倍。LmCen 免疫可产生与利什曼化相当的保护和免疫反应。LmCen 是安全的，因为它不能在免疫功能低下的小鼠中引起疾病，能诱导对媒介沙蝇挑战的强烈宿主保护，而且因为它没有标记，可以推进到人体疫苗试验。
