Institute of Microbiology, Università Cattolica del Sacro Cuore - Fondazione Policlinico Universitario GemelliRome, Italy.
Univ. Lille, Centre National de la Recherche Scientifique, Institut National de la Santé et de la Recherche Médicale, CHU Lille, Institut Pasteur de Lille, U1019 - UMR 8204 - CIIL - Centre d'Infection et d'Immunité de LilleLille, France.
Front Cell Infect Microbiol. 2017 Apr 21;7:137. doi: 10.3389/fcimb.2017.00137. eCollection 2017.
PE_PGRS33 is a surface-exposed protein of () which exerts its role in macrophages entry and immunomodulation. In this study, we aimed to investigate the polymorphisms in the gene of clinical isolates and evaluate their impact on protein functions. We sequenced in a collection of 135 clinical strains, genotyped by 15-loci MIRU-VNTR and spoligotyping and belonging to the complex (MTBC). Overall, an association between alleles and MTBC genotypes was observed and a dN/dS ratio of 0.64 was obtained, suggesting that a purifying selective pressure is acting on against deleterious SNPs. Among a total of 19 alleles identified in this study, 5 were cloned and used to complement the knock-out mutant strain of H37Rv (Δ33) to assess the functional impact of the respective polymorphisms in infections of primary macrophages. In human monocyte-derived macrophages (MDMs) infection, large in-frame and frameshift mutations were unable to restore the phenotype of H37Rv, impairing the cell entry capacity of , but neither its intracellular replication rate nor its immunomodulatory properties. studies performed in the murine model of tuberculosis (TB) demonstrated that the Δ33 mutant strain was not impaired in the ability to infect and replicate in the lung tissue compared to the parental strain. Interestingly, Δ33 showed an enhanced virulence during the chronic steps of infection compared to H37Rv. Similarly, the complementation of Δ33 with a frameshift allele also resulted in a strain capable of causing a surprisingly enhanced tissue damage in murine lungs, during the chronic steps of infection. Together, these results further support the role of PE_PGRS33 in the pathogenesis and virulence of .
PE_PGRS33 是一种表面暴露蛋白，它在巨噬细胞进入和免疫调节中发挥作用。在这项研究中，我们旨在研究 临床分离株 基因中的多态性，并评估它们对蛋白质功能的影响。我们对 135 株临床分离株的 进行了测序，这些分离株通过 15 个基因座的 MIRU-VNTR 和 spoligotyping 进行了基因分型，属于 复合群（MTBC）。总的来说，观察到 等位基因与 MTBC 基因型之间存在关联，并且获得了 0.64 的 dN/dS 比值，表明针对有害 SNP 存在净化选择压力。在本研究中总共鉴定出的 19 个 等位基因中，克隆了 5 个，并用于补充 H37Rv（Δ33）的敲除突变株，以评估各自多态性在原发性巨噬细胞感染中的功能影响。在人单核细胞衍生的巨噬细胞（MDM）感染中，大的移框和无义突变无法恢复 H37Rv 的表型，削弱了 的细胞进入能力，但不影响其细胞内复制率或免疫调节特性。在结核分枝杆菌（TB）的小鼠模型中进行的 研究表明，与亲本株相比，Δ33 突变株在感染和在肺组织中复制的能力没有受损。有趣的是，与 H37Rv 相比，Δ33 在感染的慢性阶段显示出增强的毒力。同样，用移框等位基因对 Δ33 的互补也导致了一种能够在感染的慢性阶段导致小鼠肺部组织损伤显著增强的 菌株。总之，这些结果进一步支持了 PE_PGRS33 在 发病机制和毒力中的作用。
