PDF(Pubmed)
Abstract：
We recently identified two virulence-associated small open reading frames (sORF) of Yersinia pestis, named yp1 and yp2, and null mutants of each individual genes were highly attenuated in virulence. Plague vaccine strain EV76 is known for strong reactogenicity, making it not suitable for use in humans. To improve the immune safety of EV76, three mutant strains of EV76, Δyp1, Δyp2, and Δyp1&yp2 were constructed and their virulence attenuation, immunogenicity, and protective efficacy in mice were evaluated. All mutant strains were attenuated by the subcutaneous (s.c.) route and exhibited more rapid clearance in tissues than the parental strain EV76. Under iron overload conditions, only the mice infected with EV76Δyp1 survived, accompanied by less draining lymph nodes damage than those infected by EV76. Analysis of cytokines secreted by splenocytes of immunized mice found that EV76Δyp2 induced higher secretion of multiple cytokines including TNF-α, IL-2, and IL-12p70 than EV76. On day 42, EV76Δyp2 or EV76Δyp1&yp2 immunized mice exhibited similar protective efficacy as EV76 when exposed to Y. pestis 201, both via s.c. or intranasal (i.n.) routes of administration. Moreover, when exposed to 200-400 LD50 Y. pestis strain 201Δcaf1 (non-encapsulated Y. pestis), EV76Δyp2 or EV76Δyp1&yp2 are able to afford about 50% protection to i.n. challenges, significantly better than the protection afforded by EV76. On 120 day, mice immunized with EV76Δyp2 or EV76Δyp1&yp2 cleared the i.n. challenge of Y. pestis 201-lux as quickly as those immunized with EV76, demonstrating 90-100% protection. Our results demonstrated that deletion of the yp2 gene is an effective strategy to attenuate virulence of Y. pestis EV76 while improving immunogenicity. Furthermore, EV76Δyp2 is a promising candidate for conferring protection against the pneumonic and bubonic forms of plague.
摘要：
我们最近确定了鼠疫耶尔森氏菌的两个毒力相关的小开放阅读框（sORF），命名为yp1和yp2，每个基因的无效突变体的毒力均高度减弱。鼠疫疫苗株EV76以强反应原性而闻名，使其不适合用于人类。为了提高EV76的免疫安全性，构建了EV76的三个突变株，Δyp1，Δyp2和Δyp1＆yp2，并对其毒力进行了减弱。免疫原性,并对小鼠的保护效果进行评价。所有突变菌株都通过皮下(s.c.)途径减毒,并且在组织中表现出比亲本菌株EV76更快的清除。在铁过载条件下，只有感染EV76Δyp1的小鼠存活，伴有较少的引流淋巴结损伤比感染EV76。对免疫小鼠脾细胞分泌的细胞因子的分析发现EV76Δyp2诱导多种细胞因子的高分泌,包括TNF-α,IL-2和IL-12p70比EV76。在第42天,当通过s.c.或鼻内(i.n.)施用途径暴露于鼠疫耶尔森氏菌201时,EV76Δyp2或EV76Δyp1&yp2免疫的小鼠表现出与EV76相似的保护功效。此外，当暴露于200-400LD50鼠疫杆菌菌株201Δcaf1（未封装的鼠疫杆菌）时，EV76Δyp2或EV76Δyp1&yp2能够对i.n.挑战提供约50%的保护，明显优于EV76提供的保护。120天,用EV76Δyp2或EV76Δyp1&yp2免疫的小鼠与用EV76免疫的小鼠一样迅速清除鼠疫耶尔森氏菌201-lux的i.n.攻击,显示90-100%保护。我们的结果表明，yp2基因的缺失是一种有效的策略，以减弱鼠疫耶尔森氏菌EV76的毒力，同时提高免疫原性。此外，EV76Δyp2是一个有希望的候选者，可以提供对肺炎和腺鼠疫的保护。
