Laboratory of Immunoparasitology, Institute of Biomedical Sciences, Federal University of Uberlândia, 38400-902 Uberlândia, MG, Brazil.
Immunol Lett. 2012 Apr 30;143(2):193-201. doi: 10.1016/j.imlet.2012.02.008. Epub 2012 Feb 22.
The kinetics of the humoral immune response was evaluated using the recombinant SAG2A protein comparatively to soluble Toxoplasma antigen (STAg) by ELISA in sequential serum samples of patients with toxoplasmosis up to 12 months of illness onset. The follow up of IgM and IgA levels to STAg showed a gradual decrease, with the majority of patients (88%) seropositive for IgM up to 12 months of infection, whereas IgA seropositivity was relatively low (78%) compared to IgM (100%) in the first 3 months of infection. The follow up of IgG and IgG1 antibodies showed a similar increasing profile for both SAG2A and STAg, with slightly higher seropositivity for STAg. The kinetics of IgG3 to STAg was similar to that of IgG1, contrasting with the kinetics of IgG3 to SAG2A that showed high levels up to 6 months of infection, with continuous decreasing over the time. Higher IgG3 seropositivity to SAG2A than STAg was also observed in the initial phases of infection. A higher IgG3/IgG1 ratio for SAG2A than STAg was detected in the first 3 months of infection, with decreasing profile over the time. The associations of IgG3/IgG1 ratio>1.0 with positive IgM or IgA antibodies were predominantly found in the first 3 months of infection, whereas associations of IgG3/IgG1 ratio<1.0 with positive IgM or negative IgA antibodies were mostly observed from 3 to 12 months of infection. In conclusion, our results demonstrate a differential kinetics of IgG3 antibodies to SAG2A and STAg in patients with toxoplasmosis up to 12 months of infection. Also, the IgG3/IgG1 ratio to SAG2A in association with classical serological markers of acute phase could be potential tools to distinguish early acute from convalescent phases of Toxoplasma gondii infection.
采用 ELISA 法，以重组 SAG2A 蛋白与可溶性弓形虫抗原（STAg）比较，检测了 12 个月发病期内弓形虫病患者的血清样本中体液免疫应答的动力学。对 STAg 的 IgM 和 IgA 水平进行随访发现，其逐渐下降，大多数患者（88%）在感染后 12 个月内 IgM 呈阳性，而 IgA 阳性率相对较低（78%），而在感染的前 3 个月内 IgM 阳性率为 100%。对 IgG 和 IgG1 抗体的随访表明，SAG2A 和 STAg 的 IgG 呈相似的上升趋势，STAg 的血清阳性率略高。STAg 中 IgG3 的动力学与 IgG1 相似，而 SAG2A 中 IgG3 的动力学则相反，在感染后 6 个月内 IgG3 呈高水平，随后持续下降。在感染的初始阶段也观察到 SAG2A 的 IgG3 血清阳性率高于 STAg。在感染的前 3 个月内，SAG2A 的 IgG3/IgG1 比值高于 STAg，随着时间的推移，该比值呈下降趋势。感染的前 3 个月内，IgG3/IgG1 比值>1.0 与 IgM 或 IgA 抗体阳性的相关性主要见于 IgG3/IgG1 比值<1.0，而 IgM 阳性或 IgA 阴性的相关性主要见于 IgG3/IgG1 比值与 IgM 或 IgA 抗体阳性的相关性主要见于 IgG3/IgG1 比值>1.0，而 IgM 阳性或 IgA 阴性的相关性主要见于 IgG3/IgG1 比值<1.0。结论：本研究结果表明，在感染 12 个月内，SAG2A 和 STAg 对 IgG3 抗体的动力学存在差异。此外，SAG2A 的 IgG3/IgG1 比值与急性相的经典血清标志物相关联，可能是区分急性相和恢复期弓形体感染的潜在工具。
