Laboratorio de Biología Molecular de la Enfermedad de Chagas, Instituto de Ingeniería Genética y Biología Molecular "Dr. Héctor Torres", Buenos Aires CP1428ADN, Argentina.
Centro de Biotecnología, Fundación Instituto de Estudios Avanzados, Caracas CP1080, Venezuela.
ACS Infect Dis. 2023 Mar 10;9(3):582-592. doi: 10.1021/acsinfecdis.2c00569. Epub 2023 Feb 13.
The oral transmission of Chagas disease (oCD) in Venezuela announced its appearance in 2007. Different from other populations affected by oCD and despite close supervision during treatment with nitroheterocyclic drugs, the result was treatment failure. We studied genetic features of natural bloodstream parasite populations and populations after treatment of nine patients of this outbreak. In total, we studied six hemoculture isolates, eight Pre-Tx blood samples, and 17 samples collected at two or three Post-Tx time-points between 2007 and 2015. Parasitic loads were determined by quantitative polymerase chain reaction (qPCR), and discrete typing units (DTU), minicircle signatures, and gene sequences were searched from blood samples and hemocultures. Half-maximal inhibitory concentration (IC) values were measured from the hemocultures. All patients were infected by TcI. Significant decrease in parasitic loads was observed between Pre-Tx and Post-Tx samples, suggesting the evolution from acute to chronic phase of Chagas disease. 60% of intra-DTU-I variability was observed between Pre-Tx and Post-Tx minicircle signatures in the general population, and 43 single-nucleotide polymorphisms (SNPs) were detected in a total of 12 gene sequences, indicative of a polyclonal source of infection. SNPs in three post-Tx samples produced stop codons giving rise to putative truncated proteins or displaced open reading frames, which would render resistance genes. IC values varied from 5.301 ± 1.973 to 104.731 ± 4.556 μM, demonstrating a wide range of susceptibility. The poor drug response in the Pre-Tx parasite populations may be associated with the presence of naturally resistant parasite clones. Therefore, any information that can be obtained on drug susceptibility from in vitro assays, in vivo assays, or molecular characterization of natural populations of becomes essential when therapeutic guidelines are designed in a given geographical area.
委内瑞拉宣布 2007 年出现了恰加斯病的口腔传播（oCD）。与其他受 oCD 影响的人群不同，尽管在接受硝基杂环类药物治疗时进行了密切监测，但治疗结果仍失败了。我们研究了该暴发中 9 名患者的自然血流寄生虫种群和治疗后种群的遗传特征。总共研究了六个血培养分离株、八个治疗前血液样本以及 2007 年至 2015 年期间在两个或三个治疗后时间点采集的 17 个样本。寄生虫载量通过定量聚合酶链反应（qPCR）确定，并从血液样本和血培养物中搜索离散分型单位（DTU）、小环签名和基因序列。从血培养物中测量半最大抑制浓度（IC）值。所有患者均感染了 TcI。治疗前和治疗后样本之间寄生虫载量明显下降，表明恰加斯病从急性向慢性阶段演变。在一般人群中，60%的 DTU-I 内变异性存在于治疗前和治疗后小环签名之间，总共在 12 个基因序列中检测到 43 个单核苷酸多态性（SNP），表明感染源为多克隆。三个治疗后样本中的 SNP 产生了终止密码子，导致假定的截短蛋白或移码开放阅读框，从而产生耐药基因。IC 值从 5.301 ± 1.973 到 104.731 ± 4.556 μM 不等，表明存在广泛的敏感性差异。治疗前寄生虫种群药物反应不佳可能与存在天然耐药寄生虫克隆有关。因此，在设计特定地理区域的治疗指南时，从体外检测、体内检测或自然种群的分子特征获得的任何有关药物敏感性的信息都变得至关重要。
