Determining the mechanisms by which YesMN drives pneumococcal host-to-host transmission

描述。 肺炎链球菌(Spn，肺炎球菌)，一种革兰氏阳性人类病原体，是一个重要的原因 世界范围内的发病率和死亡率。肺炎球菌导致的死亡比任何其他传染病都多， 儿童和老年人的风险最高。流行病学数据显示宿主间传播 Spn是携带者和疾病状态所需的关键的第一步，这表明它是 必须阻止主机到主机事件。然而，由于研究自然的内在复杂性 传播和缺乏可驯服的动物模型，Spn传播是最不了解的之一 这种病原体生命周期的各个方面。我们开发了一种易驯服的幼鼠模型，它允许 确定有助于传播过程的宿主和细菌因素。最近，我们 筛选随机转座子突变库(TN-seq)并鉴定其产物为 参与主机到主机的传输。这份Spn传播因素清单包括YesMN，一种定义不佳的 二组分系统(TCS)。一般而言，TCS介导了对外界反应的快速转录变化 刺激物。因此，我们在这项建议中的重点是TCS YesMN。我们假设在上呼吸道 (URT)，肺炎球菌经历YesMN促进的转录改变，YesMN感知宿主 环境和相应的响应，允许Spn持久性，并使其能够从一台主机传输到 又一个。我们通过体外rna-seq筛选确定了YesMN的可能调节基因，包括 与锌的动态平衡有关的基因。因此，在目标1中，我们将跟进这些假定的规则 成员，并确定他们在传播过程中的贡献。我们还将测试锌是否具有高度的 受宿主调节的金属，作为YesMN的信号。因为肺炎球菌肺炎被认为是一种临床 甲型流感病毒(IAV)感染的并发症，我们进一步测试了YesMN在 Spn-IAV混合感染设置。我们观察到，在并发IAV感染的情况下，Spn修改了其 转录组，YesMN的显著贡献，它在城市轨道交通中提供了健康优势。通过 在Aim#2中采取单独的方法，我们将对获得的样本进行一种新颖的活体RNA-seq筛选 并确定YesMN调控的基因，这些基因可能参与提供健身 在这些动态混合感染条件下对Spn的影响。我们目前的研究结果将第一次， 了解在URT中发生的促进宿主到宿主的Spn转录动力学 传播以及已确定的因素是否可以成为减少肺炎球菌病的潜在目标 负担。

Description. Streptococcus pneumoniae (Spn, the pneumococcus), a gram-positive human pathogen, is a significant cause of morbidity and mortality worldwide. Pneumococcus causes more deaths than any other infectious disease, with children and the elderly at the highest risk. Epidemiological data suggest host-to-host transmission of Spn is the critical first step required for both the carrier- and the disease-state, suggesting that it is imperative to block host-to-host events. However, because of the inherent complexities in studying natural transmission and the absence of tractable animal models, Spn transmission is one of the least understood aspects of this pathogen's lifecycle. We developed a tractable infant mouse model that has allowed for the identification of host and bacterial factors that contribute towards the transmission process. More recently, we screened random pools of transposon mutants (Tn-seq) and identified novel Spn genes whose products are involved in host-to-host transmission. This list of Spn transmission factors included YesMN, a poorly defined two-component system (TCS). Generally, TCS mediate rapid transcriptional changes in response to external stimuli. Hence, our focus in this proposal is the TCS YesMN. We premise that within the upper respiratory (URT), pneumococcus undergoes transcriptional alterations facilitated by YesMN that sense the host environment and respond accordingly, allowing for Spn persistence and enable it to transit from one host to another. We identified the putative regulon of YesMN through an in vitro RNA-seq screen, which included genes involved in zinc (Zn) homeostasis. Thus, in Aim #1, we will follow up on these putative regulon members and determine their contribution to the transmission process. We will also test whether Zn, a highly regulated metal by the host, acts as a signal for YesMN. As pneumococcal pneumonia is considered a clinical complication of influenza A virus (IAV) infection, we further tested whether YesMN affects Spn fitness under the Spn-IAV coinfection setting. We observed that with a concurrent IAV infection, Spn modifies its transcriptome, with a significant contribution from YesMN, which provides a fitness advantage in the URT. By taking a separate approach in Aim #2, we will carry out a novel in vivo RNA-seq screen on samples obtained from the URT and determine YesMN regulated genes that are potentially involved in providing fitness to Spn under these dynamic coinfection conditions. Results from our current studies would, for the first time, provide an understanding of the Spn transcriptional dynamics occurring in the URT that promote host-to-host transmission and whether the identified factors could be potential targets to reduce pneumococcal disease burden.