ABSTRACT

Summary: We characterized Mycobacterium bovis BCG isolates found in lung and brain samples from a previously vaccinated patient with IFNγR1 deficiency. The isolates collected displayed distinct genomic and phenotypic features consistent with host adaptation and associated changes in antibiotic susceptibility and virulence traits.

Background: We report a case of a patient with partial recessive IFNγR1 deficiency who developed disseminated BCG infection after neonatal vaccination (BCG-vaccine). Distinct M. bovis BCG-vaccine derived clinical strains were recovered from the patient’s lungs and brain.

Methods: BCG strains were phenotypically (growth, antibiotic susceptibility, lipid) and genetically (whole genome sequencing) characterized. Mycobacteria cell infection models were used to assess apoptosis, necrosis, cytokine release, autophagy, and JAK-STAT signaling.

Results: Clinical isolates BCG-brain and BCG-lung showed distinct Rv0667 rpoB mutations conferring high- and low-level rifampin resistance; the latter displayed clofazimine resistance through Rv0678 gene (MarR-like transcriptional regulator) mutations. BCG-brain and BCG-lung showed mutations in fadA2, fadE5, and mymA operon genes, respectively. Lipid profiles revealed reduced levels of PDIM in BCG-brain and BCG-lung and increased TAGs and Mycolic acid components in BCG-lung, compared to parent BCG-vaccine. In vitro infected cells showed that the BCG-lung induced a higher cytokine release, necrosis, and cell-associated bacterial load effect when compared to BCG-brain; conversely, both strains inhibited apoptosis and altered JAK-STAT signaling.

Conclusions: During a chronic-disseminated BCG infection, BCG strains can evolve independently at different sites likely due to particular microenvironment features leading to differential antibiotic resistance, virulence traits resulting in dissimilar responses in different host tissues.

 抽象的

摘要：我们对在先前接种疫苗的 IFNγR1 缺乏症患者的肺和脑样本中发现的牛分枝杆菌BCG 分离株进行了鉴定。收集的分离株表现出独特的基因组和表型特征，与宿主适应以及抗生素敏感性和毒力性状的相关变化一致。

背景：我们报告了一例部分隐性 IFNγR1 缺陷患者在新生儿接种疫苗（卡介苗）后出现播散性卡介苗感染的病例。从患者的肺和脑中回收了独特的牛支原体BCG 疫苗衍生的临床菌株。

方法：对 BCG 菌株进行表型（生长、抗生素敏感性、脂质）和遗传学（全基因组测序）特征。分枝杆菌细胞感染模型用于评估细胞凋亡、坏死、细胞因子释放、自噬和 JAK-STAT 信号传导。

结果：临床分离株 BCG 脑和 BCG 肺表现出不同的 Rv0667 rpoB突变，赋予高水平和低水平的利福平耐药性；后者通过 Rv0678 基因（MarR 样转录调节因子）突变表现出氯法齐明耐药性。 BCG-brain 和 BCG-lung 分别显示出fadA2、fadE5 和 mymA操纵子基因的突变。脂质谱显示，与母体 BCG 疫苗相比，BCG 脑和 BCG 肺中的 PDIM 水平降低，而 BCG 肺中的 TAG 和分枝菌酸成分增加。体外感染细胞显示，与 BCG 脑相比，BCG 肺诱导更高的细胞因子释放、坏死和细胞相关细菌负荷效应；相反，两种菌株均抑制细胞凋亡并改变 JAK-STAT 信号传导。

结论：在慢性播散性 BCG 感染期间，BCG 菌株可以在不同位点独立进化，这可能是由于特定的微环境特征导致不同的抗生素耐药性、毒力特征导致不同宿主组织产生不同的反应。