Antibody profile in patients with mild and severe leptospirosis

Leptospirosis is zoonotic disease of global importance, with over a million cases andnearly 60,000 deaths annually. Symptomatic disease presentation ranges from a mildfebrile disease with non-specific symptoms to severe forms, characterized by multi-organ failure, lung hemorrhage, and death. Factors governing severe outcomes remainunclear, but the host immune response likely plays an important role. In the presentstudy, we applied high throughput techniques to identify the antibody profiles ofpatients with severe and mild leptospirosis. We discovered a limited number ofimmunodominant antigens, specific to patients. Surprisingly, we found the antibodyrepertoire varies in patients with different clinical outcomes and hypothesized thatpatients with mild symptoms were protected from severe disease due to pre-existingantibodies, while the profile of patients with severe outcomes was representative of afirst exposure. These findings represent a substantial step forward in the knowledge ofthe humoral immune response to Leptospira infection, and we have identified newtargets for vaccine and diagnostic test development. We used protein microarray chip to profile theantibody responses of patients with severe and mild leptospirosis against the completeLeptospira interrogans serovar Copenhageni predicted ORFeome. Serum samplesfrom patients with mild or severe leptospirosis were collected twice: (i) acute sample,collected at patient admittance at the health care unit and (ii) convalescent sample,collected 5-276 days after the first sampling. Controls consisted of (i) 37 sera fromhealthy Leptospira-unexposed (naïve) volunteers from California/US and (ii) 37 serafrom healthy participants enrolled in a cohort study in a high risk urban slumcommunity in Salvador, endemic for leptospirosis.

钩端螺旋体病（Leptospirosis）是一种具有全球公共卫生重要性的人畜共患病，每年报告病例超百万例，死亡近6万例。该病的临床表现谱跨度较大，从伴随非特异性症状的轻度发热性疾病，到以多器官衰竭、肺出血乃至死亡为特征的重症形式均有出现。目前，影响疾病重症转归的相关机制仍不明确，但宿主免疫应答可能发挥关键作用。本研究采用高通量技术（high throughput techniques），对重症与轻症钩端螺旋体病患者的抗体谱进行分析。我们鉴定出有限数量的患者特异性免疫优势抗原。令人意外的是，不同临床转归患者的抗体库（antibody repertoire）存在显著差异，据此我们提出假说：轻症患者因预先存在的保护性抗体得以避免重症进展，而重症患者的抗体谱则代表首次病原体暴露后的免疫应答特征。本研究结果极大推进了我们对钩端螺旋体感染体液免疫应答的认知，并为疫苗与诊断试剂的开发鉴定了全新靶点。本研究采用蛋白质微阵列芯片（protein microarray chip），针对完整的问号钩端螺旋体哥本哈根血清型（Leptospira interrogans serovar Copenhageni）预测开放阅读框组（ORFeome），对重症与轻症钩端螺旋体病患者的抗体应答进行谱分析。研究共采集轻症与重症钩端螺旋体病患者的双份血清样本：(i) 急性期样本，即患者于医疗机构就诊时采集的血清；(ii) 恢复期样本，采集于首次采样后5至276天。对照组设置如下：(i) 37份来自美国加利福尼亚州的未接触钩端螺旋体的健康志愿者血清；(ii) 37份来自巴西萨尔瓦多市某钩端螺旋体病流行的高风险城市贫民窟队列研究中健康参与者的血清。