The role of licA phase variation in the pathogenesis of invasive disease by Haemophilus influenzae type b
The role of licA phase variation in the pathogenesis of invasive disease by Haemophilus influenzae type b
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DOI：
10.1111/j.1574-695x.2002.tb00628.x
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发表时间：
2002-11-15
影响因子：
--
通讯作者：
High, NJ
中科院分区：
文献类型：
--
作者：
Humphries, HE;High, NJ
LicA编码磷酸胆碱激酶，其催化磷酸胆碱（ChoP）并入H。流感病毒LPS。该基因的表达受到相位变化的影响，导致磷酸胆碱（ChoP）修饰的LPS结构的自发损失或获得。探讨这种现象在侵袭性疾病和H.构建了缺乏改变licA能力的流感病毒突变株。这是通过使用聚合酶链反应将5 '-CAAT-3'重复序列的框内缺失引入licA中来实现的。所得突变体，licADelta 5 '-CAAT-3'，不能关闭licA的表达，并组成型表达ChoP修饰的LPS结构，如通过用Mab 12 D9和HAS的集落免疫印迹所判断的。这导致高分子量LPS结构的合成增加，并且不存在非ChoP修饰的LPS种类，如通过T-SDS-PAGE分析所确定的。不能关闭licA的表达降低了H.在侵袭性疾病的幼年大鼠模型中，流感病毒的感染，并导致在CRP存在下对血清杀菌活性的敏感性增加。因此得出结论，通过相位变化关闭licA表达的能力提高了流感嗜血杆菌的全身存活率。(C)2002年，欧洲微生物学会联合会。由Elsevier Science B. V.出版，版权所有。
LicA encodes the enzyme phosphorylcholine kinase which catalyses the incorporation of phosphorylcholine (ChoP) into H. influenzae LPS. Expression of this gene is subject to phase variation, resulting in the spontaneous loss, or gain of phosphorylcholine (ChoP)decorated LPS structures. To investigate the role of this phenomenon in the pathogenesis of invasive disease an H. influenzae mutant was constructed which lacked the ability to phase vary licA. This was achieved by introducing an in-frame deletion of the 5'-CAAT-3' repeats into licA using polymerase chain reaction. The resultant mutant, licADelta5'-CAAT-3', was unable to switch off expression of licA and constitutively expressed ChoP-decorated LPS structures, as judged by colony immunoblotting with Mabs 12D9 and HAS. This resulted in increased synthesis of high molecular mass LPS structures and the absence of non-ChoP-decorated LPS species as determined by T-SDS-PAGE analysis. Inability to switch off the expression of licA reduced the virulence of H. influenzae in an infant rat model of invasive disease and resulted in increased sensitivity to the bactericidal activity of serum in the presence of CRP. The ability to Switch off the expression of licA through phase variation is therefore concluded to enhance the systemic survival of H, influenzae. (C) 2002 Federation of European Microbiological Societies. Published by Elsevier Science B.V. All rights reserved.