Department of Clinical and Molecular Medicine, Norwegian University of Science and Technology (NTNU), Trondheim, Norway.
Department of Medical Microbiology, St. Olavs University Hospital, Trondheim, Norway.
PLoS One. 2022 Jul 29;17(7):e0263199. doi: 10.1371/journal.pone.0263199. eCollection 2022.
Streptococcus agalactiae (group B streptococcus; GBS) is an important human pathogen causing pneumonia, sepsis and meningitis in neonates, as well as infections in pregnant women, immunocompromised individuals, and the elderly. For the future control of GBS-inflicted disease, GBS surface exposed proteins are particularly relevant as they may act as antigens for vaccine development and/or as serosubtype markers in epidemiological settings. Even so, the genes encoding some of the surface proteins established as serosubtype markers by antibody-based methods, like the R3 surface protein, are still unknown. Here, by examining a Norwegian GBS collection consisting of 140 strains, we find that R3 protein expression correlates with the presence of the gene sar5. By inducible expression of sar5 in an R3-negative bacterial strain we show that the sar5 gene product is specifically recognized by an R3 monoclonal antibody. With this we identify sar5 as the gene encoding the R3 surface protein, a serosubtype marker of hitherto unknown genetic origin.
无乳链球菌（B 群链球菌；GBS）是一种重要的人类病原体，可导致新生儿肺炎、败血症和脑膜炎，以及孕妇、免疫功能低下者和老年人的感染。为了未来控制 GBS 感染疾病，GBS 表面暴露的蛋白质特别相关，因为它们可以作为疫苗开发的抗原和/或在流行病学环境中作为血清亚型标志物。即便如此，一些通过基于抗体的方法确立为血清亚型标志物的表面蛋白的编码基因，如 R3 表面蛋白，仍然未知。在这里，通过检查由 140 株组成的挪威 GBS 集，我们发现 R3 蛋白的表达与 sar5 基因的存在相关。通过在 R3 阴性细菌菌株中诱导表达 sar5，我们表明 sar5 基因产物被 R3 单克隆抗体特异性识别。通过这种方法，我们确定 sar5 是编码 R3 表面蛋白的基因，该蛋白是迄今为止未知遗传起源的血清亚型标志物。
