Genome-Wide fitness analysis of group B Streptococcus in human amniotic fluid reveals a transcription factor that controls multiple virulence traits.
Genome-Wide fitness analysis of group B Streptococcus in human amniotic fluid reveals a transcription factor that controls multiple virulence traits.
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人类羊水中B组链球菌的全基因组适合性分析揭示了一个控制多种毒力特征的转录因子。
DOI：
10.1371/journal.ppat.1009116
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发表时间：
2021-03
期刊：
影响因子：
6.7
通讯作者：
Hooven TA
中科院分区：
文献类型：
--
作者：
Dammann AN;Chamby AB;Catomeris AJ;Davidson KM;Tettelin H;van Pijkeren JP;Gopalakrishna KP;Keith MF;Elder JL;Ratner AJ;Hooven TA
无乳链球菌（B组链球菌; GBS）仍然是严重新生儿感染的主要原因。GBS的一个方面使其在围产期期间特别致命，这是其侵入绒毛膜羊膜并持续存在于羊水中的能力，羊水营养缺乏且富含胎儿免疫因子，如抗微生物肽。我们使用下一代转座子-基因组连接测序（Tn-seq）来鉴定在人类羊水存在下促进存活的五个GBS基因。我们使用新型CRISPR抑制（CRISPRi）基因表达敲低系统证实了我们的Tn-seq发现。这项分析表明，一个基因，它编码一个GntR类转录因子，我们命名为MrvR，赋予一个显着的健身效益GBS在羊水中。我们对mrvR基因进行了同基因靶向缺失，相对于野生型亲本菌株，该基因在羊水中存在生长缺陷。mrvR缺失菌株在体外也显示出显著的生物膜缺陷。随后的体内研究表明，虽然突变体能够引起持续的小鼠阴道定殖，但用mrvR缺失菌株定殖的妊娠小鼠没有发生早产，尽管GBS持续侵入子宫和胎儿胎盘单位。相比之下，用野生型GBS定殖的怀孕小鼠始终过早分娩。在脓毒症模型中，mrvR缺失菌株显示出显著降低的致死率。为了更好地了解这种新发现的转录因子控制GBS毒力的机制，我们对野生型和mrvR缺失GBS菌株进行了RNA测序，结果表明该转录因子影响GBS染色体上多种基因的表达。核苷酸的生物合成和补救途径之间的差异表达的基因组中的高度代表性，这表明MrvR可能参与调节核苷酸的可用性。B族链球菌（GBS）是一种革兰氏阳性菌，通常定植于健康成人的肠道和生殖道，但不会引起严重症状。然而，在怀孕期间，GBS可以侵入怀孕的子宫，在那里它可以引起胎盘、胎膜和胎儿的感染--一种被称为绒毛膜炎的疾病。绒毛膜炎与严重的不良妊娠结局相关，包括死产、早产和新生儿严重感染。GBS可以在人类羊水中存活，羊水中细菌营养成分低，含有限制微生物持久性的免疫分子，这种能力可能导致GBS绒毛膜炎。这项研究的重点是单个GBS基因，该基因编码一种我们称为MrvR的遗传调节因子，我们表明该调节因子对于GBS对人类羊水的抵抗力很重要。使用一系列遗传技术结合GBS定殖和感染的动物模型，我们表明MrvR在允许GBS侵入血流并引发导致早产和死胎的炎症反应方面也起着关键作用。该研究最后对其他GBS基因进行了调查，这些基因的活性受到MrvR的调节，这似乎是GBS毒力的重要贡献者。
Streptococcus agalactiae (group B Streptococcus; GBS) remains a dominant cause of serious neonatal infections. One aspect of GBS that renders it particularly virulent during the perinatal period is its ability to invade the chorioamniotic membranes and persist in amniotic fluid, which is nutritionally deplete and rich in fetal immunologic factors such as antimicrobial peptides. We used next-generation sequencing of transposon-genome junctions (Tn-seq) to identify five GBS genes that promote survival in the presence of human amniotic fluid. We confirmed our Tn-seq findings using a novel CRISPR inhibition (CRISPRi) gene expression knockdown system. This analysis showed that one gene, which encodes a GntR-class transcription factor that we named MrvR, conferred a significant fitness benefit to GBS in amniotic fluid. We generated an isogenic targeted deletion of the mrvR gene, which had a growth defect in amniotic fluid relative to the wild type parent strain. The mrvR deletion strain also showed a significant biofilm defect in vitro. Subsequent in vivo studies showed that while the mutant was able to cause persistent murine vaginal colonization, pregnant mice colonized with the mrvR deletion strain did not develop preterm labor despite consistent GBS invasion of the uterus and the fetoplacental units. In contrast, pregnant mice colonized with wild type GBS consistently deliver prematurely. In a sepsis model the mrvR deletion strain showed significantly decreased lethality. In order to better understand the mechanism by which this newly identified transcription factor controls GBS virulence, we performed RNA-seq on wild type and mrvR deletion GBS strains, which revealed that the transcription factor affects expression of a wide range of genes across the GBS chromosome. Nucleotide biosynthesis and salvage pathways were highly represented among the set of differentially expressed genes, suggesting that MrvR may be involved in regulating nucleotide availability. Group B Streptococcus (GBS) is a species of Gram-positive bacteria that often colonizes the healthy adult intestinal and reproductive tracts without causing serious symptoms. During pregnancy, however, GBS can invade the pregnant uterus, where it can cause infection of the placenta, fetal membranes, and fetus—a condition known as chorioamnionitis. Chorioamnionitis is associated with serious adverse pregnancy outcomes, including stillbirth, preterm labor, and severe infection of the newborn. GBS can survive in human amniotic fluid, which is low in bacterial nutrients and contains immune molecules that limit microbial persistence, and this ability likely contributes to GBS chorioamnionitis. This study is focused on a single GBS gene that encodes a genetic regulator we called MrvR, which we show is important for GBS resistance to human amniotic fluid. Using a series of genetic techniques combined with animal models of GBS colonization and infection, we show that MrvR also plays a key role in allowing GBS to invade the bloodstream and trigger the inflammatory responses that lead to preterm labor and stillbirth. The study concludes with a survey of other GBS genes whose activity is regulated by MrvR, which seems to be an important contributor to GBS virulence.
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影响因子：
6.7
作者：
Carey AF;Rock JM;Krieger IV;Chase MR;Fernandez-Suarez M;Gagneux S;Sacchettini JC;Ioerger TR;Fortune SM
通讯作者：
Fortune SM
影响因子：
46.9
作者：
Doench JG;Fusi N;Sullender M;Hegde M;Vaimberg EW;Donovan KF;Smith I;Tothova Z;Wilen C;Orchard R;Virgin HW;Listgarten J;Root DE
通讯作者：
Root DE
影响因子：
6.4
作者：
DILLON, HC;GRAY, E;GRAY, BM
通讯作者：
GRAY, BM
影响因子：
3.6
作者：
Bauserman, Melissa S.;Laughon, Matthew M.;Cohen-Wolkowiez, Michael
通讯作者：
Cohen-Wolkowiez, Michael
影响因子：
4.4
作者：
Charbonneau, Amelia R. L.;Forman, Oliver P.;Waller, Andrew S.
通讯作者：
Waller, Andrew S.