Tiburcio Monique Gomes Salles, Anversa Laís, Kanunfre Kelly Aparecida, Ferreira Antonio Walter, Rodrigues Júnior Virmondes, Silva Luciana de Almeida
Department of Tropical Medicine and Infectology, Universidade Federal do Triângulo Mineiro, Uberaba, Brazil.
Clin Vaccine Immunol. 2013 Nov;20(11):1697-702. doi: 10.1128/CVI.00367-13. Epub 2013 Sep 4.
IgG avidity tests are used to discriminate acute from chronic infections. There are few reports on the IgG avidity profile of patients with visceral leishmaniasis (VL). This study investigated the anti-Leishmania IgG avidity in patients with classic VL (n = 10), patients showing clinical cure after treatment (n = 18), and asymptomatic subjects with at least one positive Leishmania test (n = 20). All subjects were from areas in Brazil where VL is endemic. Serum samples were collected from each subject on two different occasions. IgG avidity was evaluated by Western blotting. The proportion of high-avidity antibodies was higher in all samples from patients with classic VL. In contrast, low-avidity antibodies predominated in subjects with a history of VL, including 13 cases (72.2%) in the first assessment and 14 (77.8%) in the second. Fifteen (75%) of the asymptomatic subjects presented a predominance of low-avidity antibodies in the first assessment, and the frequency of high-avidity antibodies increased over time in seven subjects (35%) of this group. Antibodies against the 14- and/or 16-kDa antigen fraction were detected in the first assessment in all patients with classic VL, in 10 (55.5%) treated patients, and in 10 (50%) asymptomatic subjects. These were high-avidity antibodies in most cases. In the asymptomatic group, an increase in IgG avidity against the 14- and/or 16-kDa antigen fraction was observed in three cases (15%). The results indicate distinct responses in infected and asymptomatic subjects, probably associated with the length of time after infection. In this respect, IgG avidity tests represent a new approach to better characterize asymptomatic VL.
IgG亲和力检测用于区分急性感染和慢性感染。关于内脏利什曼病（VL）患者的IgG亲和力谱的报道较少。本研究调查了经典VL患者（n = 10）、治疗后临床治愈的患者（n = 18）以及至少一项利什曼检测呈阳性的无症状受试者（n = 20）的抗利什曼原虫IgG亲和力。所有受试者均来自巴西VL流行地区。在两个不同时间点从每个受试者采集血清样本。通过蛋白质印迹法评估IgG亲和力。经典VL患者的所有样本中高亲和力抗体的比例更高。相比之下，有VL病史的受试者中低亲和力抗体占主导，在首次评估中有13例（72.2%），第二次评估中有14例（77.8%）。15名（75%）无症状受试者在首次评估中低亲和力抗体占主导，该组中有7名受试者（35%）高亲和力抗体的频率随时间增加。在首次评估中，所有经典VL患者、10例（55.5%）接受治疗的患者和10例（50%）无症状受试者中均检测到针对14 kDa和/或16 kDa抗原组分的抗体。在大多数情况下，这些是高亲和力抗体。在无症状组中,在3例（15%）受试者中观察到针对14 kDa和/或16 kDa抗原组分的IgG亲和力增加。结果表明感染和无症状受试者有不同反应，这可能与感染后的时间长短有关。在这方面，IgG亲和力检测是更好地表征无症状VL的一种新方法。
