Nicholson M L, Ferdinand L, Sampson J S, Benin A, Balter S, Pinto S W, Dowell S F, Facklam R R, Carlone G M, Beall B
Respiratory Diseases Branch, Centers for Disease Control and Prevention, Atlanta, Georgia 30333, USA.
J Clin Microbiol. 2000 Nov;38(11):4126-30. doi: 10.1128/JCM.38.11.4126-4130.2000.
The etiologic agent of a large 1998 outbreak of poststreptococcal acute glomerulonephritis (PSGN) in Nova Serrana, Brazil, was found likely to be a specific strain of Streptococcus equi subsp. zooepidemicus from contaminated cheese (S. Balter et al., Lancet 355:1776-1780, 2000). In the present study, we used a serologic screen for a known surface-exposed virulence factor to confirm the epidemiologic findings. Using primers flanking a previously characterized M-like protein gene (J. F. Timoney et al., Infect. Immun. 63:1440-1445, 1995), we amplified and sequenced the M-like protein (designated Szp5058) gene and found it to be identical among four independent acute-phase PSGN patient isolates. Convalescent-phase sera from 33 of 44 patients in the PSGN outbreak were found to contain antibodies highly reactive to a purified Szp5058 fusion protein, compared with 1 of 17 control sera (P < 0. 0001), suggesting that Szp5058 was expressed during infection and further implicating this strain as the cause of the PSGN outbreak. The predicted signal sequence and cell wall association motif of Szp5058 were highly conserved with the corresponding sequence from S. equi subsp. zooepidemicus SzpW60, while the predicted surface-exposed portions differed markedly between these two proteins. The 5' end of the szp5058 gene, including its variable region, was identical to the szp gene from another strain associated with a previous PSGN outbreak in England (M. Barham et al., Lancet i:945-948, 1983), and the corresponding szp sequence found from the Lancefield group C type strain isolated from a guinea pig. In addition, the hypervariable (HV) portion of szp5058 was identical to a previously published HV sequence from a horse isolate (J. A. Walker and J. F. Timoney, Am. J. Vet. Res. 59:1129-1133, 1998). Three other strains of S. equi subsp. zooepidemicus, including another strain previously associated with a PSGN outbreak, were each found to contain a distinct szp gene. Two of these szp genes had HV regions identical to szp regions from isolates recovered from different host species.
1998年，巴西新塞拉纳爆发了大规模的链球菌感染后急性肾小球肾炎（PSGN），其病原体被认为可能是来自受污染奶酪的马链球菌兽疫亚种的一种特定菌株（S. Balter等人，《柳叶刀》355:1776 - 1780，2000年）。在本研究中，我们使用血清学筛查已知的表面暴露毒力因子来证实流行病学调查结果。利用位于先前已鉴定的M样蛋白基因两侧的引物（J. F. Timoney等人，《感染与免疫》63:1440 - 1445，1995年），我们扩增并测序了M样蛋白（命名为Szp5058）基因，发现它在四个独立的急性期PSGN患者分离株中是相同的。在PSGN疫情中，44名患者中有33名的恢复期血清被发现含有对纯化的Szp5058融合蛋白高度反应的抗体，而17名对照血清中只有1名有反应（P < 0.0001），这表明Szp5058在感染期间表达，进一步表明该菌株是PSGN疫情的病因。Szp5058的预测信号序列和细胞壁结合基序与马链球菌兽疫亚种SzpW60的相应序列高度保守，而这两种蛋白质的预测表面暴露部分明显不同。szp5058基因的5'端，包括其可变区，与另一株与英国先前一次PSGN疫情相关的菌株的szp基因相同（M. Barham等人，《柳叶刀》i:945 - 948，1983年），并且从豚鼠分离的兰斯菲尔德C群菌株中也发现了相应的szp序列。此外，szp5058的高变（HV）部分与先前发表的一株马分离株的HV序列相同（J. A. Walker和J. F. Timoney，《美国兽医研究杂志》59:1129 - 1133，1998年）。另外三株马链球菌兽疫亚种，包括另一株先前与PSGN疫情相关的菌株，各自都含有一个独特的szp基因。其中两个szp基因的HV区域与从不同宿主物种分离的菌株的szp区域相同。
