Nontypeable Haemophilus influenzae (NTHI) colonizes the human nasopharynx, but when the host immune response is dysregulated by upper respiratory tract (URT) virus infection, NTHI can gain access to more distal airway sites and cause disease. The NTHI type IV pilus (T4P) facilitates adherence, benign colonization, and infection, and its majority subunit PilA is in clinical trials as a vaccinogen. To further validate the strategy of immunization with PilA against multiple NTHI-induced diseases, it is important to demonstrate T4P expression under microenvironmental conditions that predispose to NTHI infection of the airway. Because URT infection commonly facilitates NTHI-induced diseases, we examined the influence of ongoing virus infection of respiratory tract epithelial cells on NTHI T4P expression in vitro. Polarized primary human airway epithelial cells (HAEs) were sequentially inoculated with one of three common URT viruses, followed by NTHI. Use of a reporter construct revealed that NTHI upregulated pilA promoter activity when cultured with HAEs infected with adenovirus (AV), respiratory syncytial virus (RSV), or rhinovirus (RV) versus that in mock-infected HAEs. Consistent with these results, pilA expression and relative PilA/pilin abundance, as assessed by quantitative reverse transcription-PCR (qRT-PCR) and immunoblot, respectively, were also significantly increased when NTHI was cultured with virus-infected HAEs. Collectively, our data strongly suggest that under conditions of URT virus infection, PilA vaccinogen induction of T4P-directed antibodies is likely to be highly effective against multiple NTHI-induced diseases by interfering with T4P-mediated adherence. We hypothesize that this outcome could thereby limit or prevent the increased load of NTHI in the nasopharynx that characteristically precedes these coinfections.

中文翻译：

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不可分型的流感嗜血杆菌对病毒感染的细胞有反应，IV型毛发表达显着增加。

非分型流感嗜血杆菌（NTHI）定居于人类鼻咽，但是当宿主免疫反应由于上呼吸道（URT）病毒感染而失调时，NTHI可以进入更多的远端气道部位并引起疾病。NTHI IV型菌毛（T4P）促进粘附，良性定植和感染，其大部分亚基PilA作为疫苗原正在临床试验中。为了进一步验证针对多种NTHI诱导的疾病的PilA免疫策略，重要的是要在易引起气道NTHI感染的微环境条件下证明T4P表达。因为URT感染通常会促进NTHI诱发的疾病，所以我们检查了正在进行的呼吸道上皮细胞病毒感染对NTHI T4P表达的影响体外。偏振主ħ UMAN一个irway ë pithelial细胞（黑斯）依次用的三种常见的URT病毒之一接种，随后NTHI。使用报告基因构建体显示，与用假病毒感染的HAEs感染的腺病毒（AV），呼吸道合胞病毒（RSV）或鼻病毒（RV）感染的HAEs培养相比，NTHI上调了pilA启动子活性。与这些结果一致，pilA用病毒感染的HAE培养NT​​HI时，分别通过定量逆转录PCR（qRT-PCR）和免疫印迹评估的PilA /菌毛蛋白相对表达和相对PilA /菌毛蛋白丰度也显着增加。总体而言，我们的数据强烈表明，在URT病毒感染的条件下，PilA疫苗原诱导的T4P定向抗体可能通过干扰T4P介导的粘附而对多种NTHI诱导的疾病高度有效。我们假设这种结果可能因此限制或防止在这些合并感染之前特征性的鼻咽NTHI负荷增加。