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

说明. 肺炎链球菌（Spn，肺炎球菌），一种革兰氏阳性的人类病原体，是一个重要的原因， 的发病率和死亡率。肺炎球菌造成的死亡人数比任何其他传染病都多， 儿童和老人的风险最高。流行病学数据表明， 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， 由于缺乏易处理的动物模型，Spn的传播是人们最不了解的疾病之一。 这种病原体生命周期的各个方面我们开发了一种易于处理的婴儿小鼠模型， 鉴定有助于传播过程的宿主和细菌因素。最近，我们 筛选转座子突变体的随机库（Tn-seq）并鉴定新的Spn基因，其产物是 参与宿主间的传播这份Spn传播因素清单包括YesMN，一个定义不明确的 双组分体系（TCS）。一般来说，TCS介导响应于外部环境的快速转录变化。 刺激。因此，我们在本提案中的重点是TCS YesMN。我们假设在上呼吸道 (URT)，肺炎球菌经历由YesMN促进的转录改变， 环境并相应地响应，允许Spn持久化，并使其能够从一个主机传输到 另我们通过体外RNA-seq筛选鉴定了YesMN的假定调节子，包括 锌（Zn）稳态相关基因。因此，在目标#1中，我们将跟踪这些假定的调节子 成员，并确定其对传输过程的贡献。我们还将测试是否锌，一个高度 由宿主调节的金属，充当YesMN的信号。由于肺炎球菌肺炎被认为是临床 在甲型流感病毒（IAV）感染的并发症中，我们进一步测试了YesMN是否影响Spn适应性。 Spn-IAV共感染环境。我们观察到，在同时感染IAV的情况下， 转录组，具有来自YesMN的显著贡献，其在URT中提供了适应性优势。通过 在目标#2中采取单独的方法，我们将对获得的样品进行新的体内RNA-seq筛选， 从URT和确定YesMN调节基因，可能涉及提供健身 在这种动态的共感染条件下，我们目前的研究结果将首次， 提供了一个了解的Spn转录动力学发生在URT，促进主机到主机 传播以及确定的因素是否可以成为减少肺炎球菌疾病的潜在目标 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.