Department of Microbiology, University of Hawaii at Manoa, Manoa, HI, 96822, USA.
Infect Immun. 2011 Oct;79(10):4010-8. doi: 10.1128/IAI.05044-11. Epub 2011 Aug 1.
Burkholderia pseudomallei, the cause of serious and life-threatening diseases in humans, is of national biodefense concern because of its potential use as a bioterrorism agent. This microbe is listed as a select agent by the CDC; therefore, development of vaccines is of significant importance. Here, we further investigated the growth characteristics of a recently created B. pseudomallei 1026b Δasd mutant in vitro, in a cell model, and in an animal model of infection. The mutant was typified by an inability to grow in the absence of exogenous diaminopimelate (DAP); upon single-copy complementation with a wild-type copy of the asd gene, growth was restored to wild-type levels. Further characterization of the B. pseudomallei Δasd mutant revealed a marked decrease in RAW264.7 murine macrophage cytotoxicity compared to the wild type and the complemented Δasd mutant. RAW264.7 cells infected by the Δasd mutant did not exhibit signs of cytopathology or multinucleated giant cell (MNGC) formation, which were observed in wild-type B. pseudomallei cell infections. The Δasd mutant was found to be avirulent in BALB/c mice, and mice vaccinated with the mutant were protected against acute inhalation melioidosis. Thus, the B. pseudomallei Δasd mutant may be a promising live attenuated vaccine strain and a biosafe strain for consideration of exclusion from the select agent list.
类鼻疽伯克霍尔德菌是一种严重且危及生命的人类病原体，因其可能被用作生物恐怖主义制剂而引起了国家生物防御关注。该微生物被疾病预防控制中心列为选择剂，因此疫苗的开发具有重要意义。在这里，我们进一步研究了最近创建的类鼻疽伯克霍尔德菌 1026bΔasd 突变体在体外、细胞模型和感染动物模型中的生长特性。该突变体的特征是无法在没有外源二氨基庚二酸（DAP）的情况下生长；通过单个拷贝与 asd 基因的野生型拷贝互补，生长恢复到野生型水平。对类鼻疽伯克霍尔德菌Δasd 突变体的进一步表征显示，与野生型和互补的Δasd 突变体相比，RAW264.7 鼠巨噬细胞的细胞毒性明显降低。感染Δasd 突变体的 RAW264.7 细胞没有表现出细胞病变或多核巨细胞（MNGC）形成的迹象，而在野生型类鼻疽伯克霍尔德菌细胞感染中观察到了这些迹象。Δasd 突变体在 BALB/c 小鼠中被发现无毒力，并且用突变体接种的小鼠可以预防急性吸入性类鼻疽病。因此，类鼻疽伯克霍尔德菌Δasd 突变体可能是一种有前途的活减毒疫苗株和生物安全株，可考虑从选择剂清单中排除。
