BMC Infect Dis. 2015 Mar 3;15:113. doi: 10.1186/s12879-015-0857-4.
Streptococcus pyogenes (group A streptococcus; GAS) is an etiological agent for pharyngitis, pyoderma, and invasive infections in humans. Pharyngitis and pyoderma may lead to serious immune sequelae such as rheumatic heart disease and post-streptococcal glomerulonephritis (PSGN). Streptococcal Inhibitor of Complement (SIC) and its orthologue, distantly related to SIC (DRS), are virulence factors expressed by only four of more than 100 M types of GAS. These four types (M1, M57, M12 and M55) are among the M types, which are associated with PSGN. In several populations PSGN has been shown to be a risk factor for chronic kidney disease (CKD) and end-stage renal disease (ESRD). Previous studies showed SIC or DRS antibody-prevalence was associated with PSGN, and seroprevalence of SIC antibodies is significantly high among CKD and ESRD patients in Mumbai.
Streptococcal isolates recovered from GAS pyoderma cases were typed. Seropositivity for SIC and DRS antibodies in subjects with pyoderma, PSGN pediatric cases, age matched healthy controls and non-GAS pyoderma cases were determined.
We confirm in this study an association between seroprevalence to SIC and DRS antibodies, and PSGN in Mumbai population despite low point prevalence of M1, M12, M55 and M57. In addition we extended the study to GAS-pyoderma and non-GAS pyoderma cases. To our surprise, we found a positive association between the seroprevalence to SIC and DRS antibodies, and GAS-pyoderma owing to infection with diverse M types. The mechanism of increased predisposition to pyoderma owing to infection by diverse GAS among SIC or DRS antibody-positive population is not clear. Nonetheless, our findings could be explained by a phenomenon akin to antibody-dependent enhancement (ADE).
This is the first report showing a small number of GAS M types conferring predisposition to pyoderma by diverse types. Implications of this ADE-like phenomenon are discussed in the light of evolutionary advantage to GAS, vaccine design and control of renal diseases.
化脓性链球菌（A 组链球菌；GAS）是人类咽炎、脓疱病和侵袭性感染的病原体。咽炎和脓疱病可导致风湿性心脏病和链球菌后肾小球肾炎（PSGN）等严重免疫后遗症。链球菌补体抑制剂（SIC）及其远缘相关物（DRS）是仅在超过 100 种 GAS M 型中的 4 种表达的毒力因子。这四种类型（M1、M57、M12 和 M55）是与 PSGN 相关的 M 型之一。在多个人群中，PSGN 已被证明是慢性肾脏病（CKD）和终末期肾病（ESRD）的危险因素。先前的研究表明，SIC 或 DRS 抗体的流行率与 PSGN 相关，而且在孟买的 CKD 和 ESRD 患者中，SIC 抗体的血清阳性率显著较高。
从 GAS 脓疱病病例中分离出链球菌分离株进行分型。在脓疱病患者、PSGN 儿科病例、年龄匹配的健康对照者和非 GAS 脓疱病患者中，确定 SIC 和 DRS 抗体的血清阳性率。
尽管 M1、M12、M55 和 M57 的点流行率较低，但在本研究中，我们证实了 SIC 和 DRS 抗体与孟买人群 PSGN 之间的关联。此外，我们将研究扩展到 GAS 脓疱病和非 GAS 脓疱病病例。令我们惊讶的是，我们发现 SIC 和 DRS 抗体的血清阳性率与 GAS 脓疱病之间存在正相关，这归因于多种 M 型的感染。在 SIC 或 DRS 抗体阳性人群中，由于感染了多种 GAS，导致对脓疱病的易感性增加的机制尚不清楚。尽管如此，我们的发现可以用类似于抗体依赖性增强（ADE）的现象来解释。
这是第一项报告表明少数 GAS M 型通过多种类型赋予脓疱病易感性。在考虑到 GAS 的进化优势、疫苗设计和肾脏疾病控制的情况下，讨论了这种类似于 ADE 的现象的含义。
