为了建立一种可以同时鉴定大肠杆菌O8、O9、O149与O157血清型的快速高效多重PCR检测方法,本研究根据GenBank中大肠杆菌O8、O9、O149、O157血清型的O 抗原合成基因簇特异性靶标基因序列,设计合成4对PCR引物,优化引物浓度及反应条件,建立多重PCR检测方法.然后,分析多重PCR方法的特异性、敏感性,并利用建立的多重PCR方法检测大肠杆菌临床分离株验证该方法的可靠性.特异性结果显示,多重PCR方法可有效鉴定大肠杆菌O8、O9、O149、O157血清型,而检测其他血清型大肠杆菌及菌种时无扩增条带,表明多重PCR方法具有较好的特异性.敏感性结果显示,多重PCR方法检测大肠杆菌O8、O9、O149、O157血清型的菌液和DNA的最低检测限分别为105 CFU、105 CFU、103 CFU、103 CFU和1 ng、100 pg、10 pg、10 pg.临床分离株检测结果显示,与传统血清凝集试验相比,多重PCR方法更准确、可靠.本研究成功建立了一种可特异、灵敏、快速鉴定大肠杆菌O8、O9、O149与O157血清型的多重PCR方法,为大肠杆菌O8、O9、O149与O157血清型检测和流行病学调查提供了新的技术手段.

The duck Tembusu virus (DTMUV) is a novel mosquito-borne Flavivirus which caused huge economic losses for poultry industries in Southeast Asia and China. Currently, no effective antiviral drugs against this virus have been reported. (-)-Epigallocatechin-3-gallate (EGCG), a polyphenol present in abundance in green tea, has recently been demonstrated to have an antiviral activity for many viruses; however, whether EGCG can inhibit DTMUV infection remains unknown. Here, we tried to explore the anti-DTMUV effects and mechanisms of EGCG both in vitro and in vivo. Several EGCG treatment regimens were used to study the comprehensive antiviral activity of EGCG in DTMUV-infected baby hamster kidney cell line (BHK-21). The DTMUV titers of mock- and EGCG-treated infected cell cultures were determined using the tissue culture infective dose assay and the DTMUV mRNA copy number as determined using quantitative Real Time PCR. Moreover, the therapeutic efficacy of EGCG against DTMUV was assessed in DTMUV-infected ducklings. Our results suggested that EGCG significantly reduced the viral infection in BHK-21 cells in a dose-dependent manner, as reflected by the reduction of virus titers, virus copy number, and the expressions of viral E protein. We also observed that EGCG exhibited direct virucidal abilities against DTMUV. Notably, a significant reduction in virus binding ability was also observed, indicating that EGCG possesses excellent inhibitory effects on the viral adsorption step. In addition, DTMUV replication was also suppressed in BHK-21 cells treated with EGCG after viral entry, likely because of upregulation of the levels of interferon alfa and interferon beta. Finally, we also proved that EGCG exhibited anti-DTMUV efficacy in a duckling infection model because the survival rate was significantly improved. This is the first study to demonstrate the protective effect of EGCG against DTMUV, suggesting its potential use as an antiviral drug for DTMUV infection.

采用RT-PCR扩增获得鹅星状病毒(Goose astrovirus)的衣壳纤突蛋白基因vp27,并将其克隆至pCold-SUMO原核表达载体.重组表达载体pCold-vp27经过测序和双酶切验证正确后,转化到感受态细胞Rosetta.挑取阳性克隆子,利用异丙基硫代半乳糖苷诱导表达鹅星状病毒衣壳纤突重组蛋白,使用镍柱纯化衣壳纤突蛋白VP27,将定量的重组蛋白免疫BALB/c小鼠.利用ELISA、Western blot和IFA鉴定鼠抗衣壳纤突蛋白VP27多克隆抗体.结果显示,鼠抗衣壳纤突蛋白VP27多克隆抗体的效价大于1:64000,Western blot试验结果证明了鼠抗衣壳纤突蛋白VP27多克隆抗体的特异性,IFA试验结果证明鼠抗衣壳纤突蛋白VP27多克隆抗体能够识别天然的鹅星状病毒衣壳纤突蛋白VP27.

近年来抗生素的不合理使用导致细菌耐药性问题逐渐加剧,开发新型有效的抗菌制剂迫在眉睫.噬菌体及其溶菌酶具有特异性强、抗菌效力强、安全性高、筛选周期短、绿色安全及不易产生耐药等优势,可作为一种天然抗菌剂防控细菌病.为了分析广宿主谱沙门菌噬菌体SHWT1的溶菌酶抑菌活性,本文将沙门菌裂解性噬菌体SHWT1的溶菌酶lys基因克隆至表达载体pET28a(+),然后转化至大肠杆菌BL21(DE3)中进行表达,纯化后获得了大小19 kDa、浓度为2 mg/mL的高纯度融合蛋白LysSHWT1.平板裂解实验显示,溶菌酶重组蛋白LysSHWT1对鸡白痢沙门菌、肠炎沙门菌、鼠伤寒沙门菌、鸡伤寒沙门菌具有较好的裂解活性,裂菌圈直径分别为16、13、14、13 mm,对照组无裂解圈;裂菌谱结果显示,LysSHWT1对101株临床沙门菌株中的60株菌株存在裂解作用,未发现能裂解除沙门菌外的其他菌株;进一步研究发现,溶菌酶在EDTA的协同作用下可以展现更好的抑菌活性,使鸡白痢沙门菌SP01、鸡伤寒沙门菌SG02、鼠伤寒沙门菌SAT52、肠炎沙门菌SE12滴度显著下降(P＜0.05).本研究表明广宿主谱沙门菌噬菌体溶菌酶LysSHWT1可有效裂解沙门菌,在防控沙门菌感染方面具有潜在的应用价值.

Since 2010, several duck Tembusu viruses (DTMUVs) have been isolated from infected ducks in China, and these virus strains have undergone extensive variation over the years. Although the infection rate is high, the mortality rate is usually relatively low—~5%–30%; however, since fall 2019, an infectious disease similar to DTMUV infection but with a high mortality rate of ~50% in goslings has been prevalent in Anhui Province, China. The present study identified a new Tembusu virus, designated DTMUV/Goose/China/2019/AQ-19 (AQ-19), that is believed to be responsible for the noticeably high mortality in goslings. To investigate the genetic variation of this strain, its entire genome was sequenced and analysed for specific variations, and goslings and mice were challenged with the isolated virus to investigate its pathogenicity. The AQ-19 genome shared only 94.3%–96.9% and 90.9% nucleotide identity with other Chinese and Malaysian DTMUVs, respectively; however, AQ-19 has high homology with Thailand DTMUVs (97.2%–98.1% nucleotide identity). Phylogenetic analysis of the E gene revealed that AQ-19 and most of Thailand DTMUVs form a branch separate from any of the previously reported DTMUV strains in China. After the challenge, some goslings and mice showed typical clinical signs of DTMUV, particularly severe neurological dysfunction. AQ-19 has high virulence in goslings and mice, resulting in 60% and 70% mortality through intramuscular and intracerebral routes, respectively. Pathological examination revealed severe histological lesions in the brain and liver of the infected goslings and mice. Taken together, these results demonstrated the emergence of a novel Tembusu virus with high virulence circulating in goslings in China for the first time, and our findings highlight the high genetic diversity of DTMUVs in China. Further study of the pathogenicity and host range of this novel Tembusu virus is particularly important.

为了建立一种能鉴定大肠杆菌O8、O9血清型的高效、快速的双重PCR方法,参考GenBank中大肠杆菌O8、O9血清型的O抗原合成基因簇序列筛选特异性靶标基因并设计合成2对PCR引物,通过优化反应条件,分析双重PCR方法的特异性、敏感性,通过检测大肠杆菌临床分离株验证双重PCR的实用性.结果显示,所建立的双重PCR方法可有效鉴定O8、O9血清型大肠杆菌,对其他血清型大肠杆菌及菌株则无交叉反应,表明PCR方法的特异性好;O8和O9血清型的菌体最低检出限分别为1×103CFU/mL和1×104 CFU/mL,其DNA最低检出限分别为10 pg/μL和500 pg/μL.临床分离菌株检测显示,双重PCR检测结果与传统血清凝集结果一致.结果表明,本研究建立的双重PCR方法可有效、特异、灵敏、快速鉴定大肠杆菌O8、O9血清型,为大肠杆菌O8、O9血清型检测及其流行病学调查提供了新的技术手段.