Arroyave Esteban, Hyseni Ilirjana, Burkhardt Nicole, Kuo Yong-Fang, Wang Tian, Munderloh Ulrike, Fang Rong
Department of Pathology, University of Texas Medical Branch, Galveston, TX 77555, USA.
Department of Entomology, University of Minnesota, St. Paul, MN 55108, USA.
Pathogens. 2021 Jun 30;10(7):819. doi: 10.3390/pathogens10070819.
Although rickettsiae can cause life-threatening infections in humans worldwide, no licensed vaccine is currently available. To evaluate the suitability of live-attenuated vaccine candidates against rickettsioses, we generated a mutant RPATATE_0245::pLoxHimar (named 3A2) by insertion of a modified pLoxHimar transposon into the gene encoding a phage integrase protein. For visualization and selection, 3A2 expressed mCherry fluorescence and resistance to spectinomycin. Compared to the parent wild type (WT) , the virulence of 3A2 was significantly attenuated as demonstrated by significantly smaller size of plaque, failure to grow in human macrophage-like cells, rapid elimination of and ameliorated histopathological changes in tissues in intravenously infected mice. A single dose intradermal (i.d.) immunization of 3A2 conferred complete protection against both fatal and rickettsioses in mice, in association with a robust and durable rickettsiae-specific IgG antibody response. In summary, the disruption of RPATATE_0245 in resulted in a mutant with a significantly attenuated phenotype, potent immunogenicity and protective efficacy against two spotted fever group rickettsioses. Overall, this proof-of-concept study highlights the potential of mutants as a live-attenuated and multivalent vaccine platform in response to emergence of life-threatening spotted fever rickettsioses.
尽管立克次氏体可在全球范围内导致人类危及生命的感染，但目前尚无获得许可的疫苗。为了评估减毒活疫苗候选株对立克次氏体病的适用性，我们通过将修饰的pLoxHimar转座子插入编码噬菌体整合酶蛋白的基因中，构建了一个突变体RPATATE_0245::pLoxHimar（命名为3A2）。为了便于可视化和筛选，3A2表达mCherry荧光并对壮观霉素具有抗性。与亲本野生型（WT）相比，3A2的毒力显著减弱，表现为噬斑尺寸明显更小、无法在人巨噬细胞样细胞中生长、在静脉感染小鼠的组织中迅速清除以及组织病理学变化得到改善。单剂量皮内（i.d.）接种3A2可使小鼠完全抵御致命的[立克次氏体病名称1]和[立克次氏体病名称2]立克次氏体病，同时伴有强烈且持久的立克次氏体特异性IgG抗体反应。总之，[立克次氏体名称]中RPATATE_0245的破坏产生了一个具有显著减毒表型、强大免疫原性和对两种斑点热群立克次氏体病具有保护效力的突变体。总体而言，这项概念验证研究突出了[立克次氏体名称]突变体作为应对危及生命的斑点热立克次氏体病出现的减毒活多价疫苗平台的潜力。
