2003～2007年中国风疹病毒基因特征分析

本研究用Vero细胞或Vero/SLAM细胞从我国10个省(直辖市、自治区,下同)2003～2007年风疹暴发和散发病例的咽拭子标本中分离到57株风疹病毒,用RT-PCR方法扩增了57株风疹病毒E1基因1 107个核苷酸的片段,并对该PCR产物进行序列测定和分析.结果提示,在基于WHO基因定型靶序列739个核苷酸片段构建的基因亲缘关系树上,其中55株风疹病毒株属于1E基因型,相对于其他国家的1E基因型,形成一个独立分支;另外2株风疹病毒属于2B基因型.57株风疹病毒大部分核苷酸的突变为无义突变,氨基酸序列高度保守,除了2株风疹病毒在E1蛋白血凝抑制和中和位点区域第212位氨基酸由Thr变为Ser,其他病毒株均无重要抗原位点的改变;所有我国已分离到的1E基因型风疹病毒在E1蛋白第338位氨基酸共享突变位点(Leu338→Phe338),而其他基因型以及其他国家的1E基因型风疹病毒在该位点均未发生突变,提示该氨基酸(Phe338)可能是我国1E基因型风疹病毒所特有.2003～2007年在我国10个省均分离到1E基因型,而2B基因型只在2006年从四川省的越南输入病例中分离到,提示1E为绝对优势基因型,2B基因型为输入基因型.与1979～1984年和1999～2002年我国流行的风疹基因型不同,发生了基因型的更替,近年我国风疹的流行是由1E基因型为主的风疹野病毒的多个传播链引起.     

辽宁省2007～2012年流行风疹病毒基因特征分析

为了解辽宁省2007~2012年流行性风疹病毒基因特征,本研究用Vero/Slam细胞从辽宁省2007~2012年风疹暴发和散发患者的咽拭子标本中分离到145株风疹病毒(Rubella,RV),应用逆转录-聚合酶链反应(RT-PCR)扩增RV分离株E1基因的945个核苷酸片段,对扩增产物进行序列测定和分析。将辽宁省145株RV与世界卫生组织(WHO)RV 13个基因型的32株参考株基于739个核苷酸片段的基因定型序列构建基因亲缘性关系树。结果提示,辽宁省2007~2012年145株RV分离株均属于1E基因型,核苷酸和氨基酸同源性为97.2%~100.0%和97.6%~100.0%。与2株WHO 1E基因型参考株(Rvi/Dezhou.CHN/02,RVi/MYS/01)序列相比,核苷酸和氨基酸同源性分别为96.6%~99.2%和98.2%~100.0%.除RVi/Shenyang.Liaoning.CHN/13.11/13株病毒在E1基因的第246位发生了突变(Val246-Ala246);RVi/Shenyang.Liaoning.CHN/13.11/4和RVi/Liaoyang.Liaoning.CHN/26.11/2株病毒在E1基因的第262发生相同突变(Asp262-Asn262)外,其他毒株在N-型糖基化位、血凝抑制位点和中和位点等重要抗原位点均未发生变化,抗原性稳定。辽宁省所有1E基因型风疹病毒在E1蛋白的第338位氨基酸发生相同突变(Leu338-Phe338)。本研究证实1E基因型为辽宁省RV的优势基因型,近6年来辽宁省风疹疫情是由1E基因型RV的多个传播链引起。     

2001～2011年上海市风疹病毒分子流行病学研究

本研究对2001～2011年本实验室保存的血清标本检测结果为麻疹IgM阴性,风疹IgM阳性病例相对应的咽拭子标本进行风疹病毒（Rubella virus,RV）分离,用RT-PCR方法对细胞培养产物鉴定后扩增病毒E1基因,扩增产物用于核苷酸序列测定,并进行分子流行病学分析。结果表明,60份咽拭子标本共分离到31株RV,获得27株RV的739nt（nt8 731～nt9 469）核苷酸序列,系统同源性分析表明,27株RV分离株分别属于两个不同的基因型,除分离自2011年的11009株、11052株和11106株为2B基因型外,其他分离株均为1E基因型。27株RV分离株大部分的核苷酸突变为无义突变,氨基酸序列高度保守。24株1E基因型分离株中大部分毒株氨基酸序列完全一致,自2001年以来可能有来自同一传播链的RV在持续传播。本研究首次监测到2B基因型RV2011年开始在上海流行,经GenBank核苷酸序列比对发现,其与越南、日本、阿根廷等国家近几年的RV分离株核苷酸序列同源性达99%。由于以前对风疹的监测较少,尚不能证明其来源。     

2020年我国风疹流行病学和病毒基因特征分析

为了解2020年我国风疹流行病学特征以及流行风疹病毒(Rubella virus,RV)的基因特征,本研究收集整理全国麻疹/风疹监测信息报告管理系统中2020年中国风疹发病数据,分析其流行病学特征;同时,依托全国麻疹/风疹实验室网络获得RV分离株,经鉴定后扩增并测定阳性RV分离株的靶基因序列——E1基因的739个核苷酸片段,并与WHO推荐的基因型参考株序列以及已发表的基因亚型参考株序列进行比对确定基因型和亚型,同时与我国2000-2019年间流行的RV进行亲缘性关系分析.结果显示,2020年中国风疹报告发病率为0.18/10万,继2018-2019年风疹的复发和暴发后出现大幅下降,发病人群年龄组主要为10-29岁无免疫史的青少年和成人;2020年我国RV流行的主要基因亚型为1E-L2与2B-L2c,为2018-2019年间检测到的境外输入性病毒.因此,在实施有效的风疹疫苗免疫后,我国本土流行的病毒逐渐被阻断,然而由于我国风疹易感人群的累积和输入性病毒的持续传播导致了我国近些年风疹疫情的回升.鉴于此,我国应根据现状制定更加切实有效的风疹疫苗免疫策略,消除青少年和成年人中的易感人群;同时应进一步加强风疹流行病学和病毒学监测,从而科学地阻断输入病毒的传播.     

中国大陆流行的风疹病毒的变异变迁规律研究

从分子水平上探讨1999~2015年中国大陆流行的风疹病毒动态变异变迁规律。方法依据全国麻疹/风疹实验室网络的风疹病毒学监测数据,对1999~2015年中国流行风疹病毒进行分子进化分析。1999~2015年从全国29个省市(除新疆和西藏外)共获得风疹病毒株1737株,分属于4个基因型(1E,1F,2A和2B基因型):11E基因型风疹病毒自2001年首次分离到之后,替代1F基因型风疹病毒成为2001~2013年中国流行风疹病毒的优势基因型,并从年代上可分为两个进化分支[Cluster A(2004-2015)和Cluster B(2001-2009)],然而自2011年其检出比例逐渐下降,至2015年该比例仅为1.3%;21F基因型风疹病毒在地理上局限于中国,而在2002年之后未再监测到,推测其在中国的传播可能已被阻断;32A基因型风疹病毒株均来自于疫苗相关病例;42000~2015年间中国至少有4个不同的2B基因型风疹病毒传播链(Lineage1-4),2B基因型风疹病毒在2010年之前只有零星的流行,一直处于弱势,但自2011年输入型2B基因型风疹病毒(Lineage 3)的检出构成比逐年增高,并在2014~2015年成为中国流行风疹病毒的主要基因型。通过对中国连续16年风疹病毒变异变迁规律的研究,系统地掌握了其进化和流行规律,同时也为中国风疹控制和将来消除提供了重要的病毒学监测数据。     

辽宁省2008～2011年流行性腮腺炎野病毒SH蛋白基因特征分析

本研究用Vero/Slam细胞从辽宁省2008～2011年流行性腮腺炎暴发和散发患者的临床标本中分离到13株流行性腮腺炎野病毒(Mumps virus,MuV),应用逆转录-聚合酶链反应(RT-PCR)针对MuV分离株的SH基因的316个核苷酸片段进行扩增,并对该产物进行序列测定。将这13株MuV与从GenBank下载的世界卫生组织(WHO)MuV基因型参考株一起进行分子流行病学研究。结果提示:除2011-015株外,辽宁省2008～2011年12株MuV分离株均属于F基因型,核苷酸和氨基酸同源性为94.9%～100%和83.3%～100%。与F基因型参考株序列相比,核苷酸和氨基酸同源性分别为92.4%～97.2%和96.5%～84.2%。表明2008～2011年辽宁省流行的F基因型MuV发生较大的型内变异。另外还发现F基因型MuV在SH基因上存在着特异性突变(CNt65,CNt105,G Nt137,C Nt192,C Nt239,GNT262),而其它基因型MuV在这些位点上均未发生改变。F基因型MuV在SH基因编码的氨基酸保守位点也发生变化。如:第2位上由S→P,第6位上由P→L,第23位上由T→N,第48位上由L→P/R。与基因分型有关的氨基酸三联体,2008-01-007毒株也发生了改变,由IML变为TMP。2011-015株病毒与F基因型参考株平均核苷酸和氨基酸同源性分别为87.5%和79.8%,与G型参考株平均核苷酸和氨基酸同源性分别为96.8%和97.4%,属于G基因型。该基因型为中国内地首次发现。     

河南省麻疹病毒血凝素蛋白基因特征分析

为了解河南省流行的麻疹野病毒的血凝素基因特征,为制定消除麻疹策略提供依据,本文对2008~2012年河南省麻疹病毒分离株进行了血凝素基因核苷酸氨基酸特征研究。该研究采用病毒分离、RT-PCR方法获取病毒血凝素基因扩增产物,再对扩增产物进行核苷酸序列测定和分析。结果显示,河南省2008~2012年共分离麻疹病毒12株,测序结果显示均为H1a基因型,核苷酸同源性98.0%~100%,氨基酸序列同源性97.2%~99.8%,通过与Edmonston-wt.USA/54/A毒株进行比较,在氨基酸240位点发生丝氨酸(S)突变成天门酰胺(N)的突变。上述检测结果显示,河南省2008~2012年麻疹野病毒流行优势株为H1a基因型,同源性较高,而且氨基酸改变导致糖基化位点的缺失,是麻疹病毒变化的共同特征。     

河北省儿童病毒性脑炎及脑膜炎埃可病毒30型VP1基因特征分析

为了解河北省儿童病毒性脑炎和脑膜炎患者中埃可病毒30型(Echovirus 30,E30)流行株基因特征及进化。本研究对2013～2015年间河北省儿童病毒性脑炎和脑膜炎病例中151份鉴定为肠道病毒阳性的脑脊液标本进行血清型鉴定,扩增E30流行株VP1区全基因序列;并与GenBank下载的325株E30的VP1基因序列进行同源性及亲缘关系分析。共获得18条E30 VP1基因序列。亲缘性分析显示E30可分为A～H 8个基因型;我国E30流行株主要为D、E、G和H基因型;本研究中E30流行株均为H基因型。18条E30 VP1基因核苷酸同源性为93.3%～100%,氨基酸同源性为98.2%～100%,与原型株(Bastianni)核苷酸和氨基酸同源性分别为80.9%～81.1%和91.4%～92.4%。该研究中18株E30与我国浙江省和山东省的分离株核苷酸和氨基酸同源性最高。2013～2015年间引起河北省儿童病毒性脑炎和脑膜炎的E30流行株为H基因型,可能存在多个传播链。     

辽宁省流行性腮腺炎野病毒的分离与鉴定

本研究用Vero/Slam细胞首次从辽宁省2008年流行性腮腺炎暴发和散发患者的临床标本中分离到3株流行性腮腺炎野病毒(Mumps virus,MuV),应用逆转录-聚合酶链反应(RT-PCR)针对MuV分离株的包括SH基因的1 028个核苷酸片段进行PCR扩增,将扩增产物连接在pMD19-T载体后转化到大肠杆菌中进行克隆。通过蓝白斑筛选,将鉴定为阳性的白色菌落进行核苷酸序列测定分析。将这3株MuV结合从GenBank下载的世界卫生组织(WHO)MuV基因型参考株在基于WHO基因定型靶序列SH基因的316核苷酸片段构建基因亲缘关系树,一起进行分子流行病学研究。结果提示:辽宁省2008年3株MuV分离株的核苷酸和氨基酸同源性在98.7%～100%和94.7%～100%之间,其中LN-2008-001-06与LN-2008-001-10序列完全一致;与F基因型参考株序列相比,核苷酸和氨基酸同源性分别为92.4%～96.2%和84.2%～94.7%。提示辽宁省2008年3株流行性腮腺炎野病毒分离株均属F基因型。由于此次毒株数量太少,尚不能说明F基因型是否为辽宁省的优势基因型,需进一步扩大范围加强监测。     

Diarrheal and Environmental Isolates of Aeromonas spp. Produce a Toxin Similar to Shiga-Like Toxin 1

Diarrheal and environmental isolates of 39 strains of Aeromonas spp. were studied for detection of virulence factors. Although these 39 strains did not produce either heat-labile or heat-stable enterotoxins, culture filtrates of 31 strains produced cytopathic effects on Vero cells. Among these, culture filtrates of three strains of Aeromonas hydrophila and one strain of Aeromonas caviae could be neutralized by Escherichia coli O157:H7 Shiga-like toxin 1 antiserum. A single band of plasmid DNA of 2.14 kbp was isolated from these strains of Aeromonas spp. and E. coli O157:H7, which could be amplified by the polymerase chain reaction (PCR), employing oligonucleotide primers from the Shiga-like toxin 1 (SLT1) gene of E. coli O157:H7. E. coli HB 101 cells when transformed with the same plasmid showed cytopathic effects on Vero cells, which indicates that the SLT 1 homolog gene(s) of Aeromonas spp. is plasmid encoded. These results suggest that Aeromonas spp. may also produce Shiga-like toxin 1, or at least a cytotoxin with some homology with the Shiga-like toxin 1 of E. coli O157:H7.     

Pathogenic characteristics of Escherichia coli strains in cases of asymptomatic bacteriuria and symptomatic urinary tract infections

The aim of this study was to examine if E. coli isolated from asymptomatic bacteriuria differed in pathogenic features from strains isolated from symptomatic infections of urinary tract. In this study 130 strains of E. coli isolated from women having asymptomatic bacteriuria and 112 strains isolated from patients with symptoms of urinary tract infection were examined. It was shown that E. coli isolated from patients with symptomatic urinary tract infection showed the more frequently ability to cause mannose-resistant haemagglutination of human erythrocytes, resistance to bactericidal activity of serum and haemolytic properties than those isolated from asymptomatic bacteriuria. These strains showed also the higher ability to adhere to Vero cells in tissue culture. Among E. coli strains isolated from persons with asymptomatic bacteriuria the pathogenic features were most frequently found in strains from healthy women and the most rarely in isolated from diabetic women.     

Hemadsorption expressed by cloned H genes from subacute sclerosing panencephalitis (SSPE) viruses and their possible progenitor measles viruses isolated in Osaka, Japan

Most subacute sclerosing panencephalitis (SSPE) viruses, including our Osaka-1, -2, and -3 strains isolated in Osaka, have shown negative hemadsorption (HAD) by African green monkey red blood cells. This property has been thought to be characteristic of SSPE virus as compared to the positive reaction of the standard Edmonston strain of measles virus (MV). However, this assumption has become quite obscure because MV mutates frequently at the genetic level during its multiplication and also because recent field strains isolated by lymphoblastoid cell lines have shown negative HAD. To investigate the above issue, the nucleotide sequences of the hemagglutinin (H) genes from SSPE virus Osaka-1, -2, or -3 strains were compared to those of various MV field strains isolated in Osaka by Vero cells. The H gene sequences of three SSPE strains were relatively conserved without such biased hypermutation as had been observed in the matrix (M) gene of three SSPE strains. However, this analysis of the H gene sequence of the SSPE viruses enabled us to deduce possible progenitor MVs, which are in agreement with the deduction from the M gene analysis we reported previously. The HAD of Vero cells transfected with the cloned H cDNAs from the SSPE strains and their progenitors suggested that negative HAD of the SSPE viruses has been maintained as one of original properties of the progenitor MVs rather than having been acquired as an altered one during long-term persistent infection in the brains of patients with SSPE.     

Examination of retail chickens and sausages in Britain for vero cytotoxin-producing Escherichia coli.

Samples from chickens and pork sausages were examined for the presence of Vero cytotoxin-producing Escherichia coli by using DNA probes for the Vero cytotoxin genes. Hybridization was detected in 25% of the 184 sausage samples, but none of the chickens was positive. No E. coli O157:H7 strains were isolated, and serotyping showed that the Vero cytotoxin-producing E. coli strains belonged to eight different O serogroups and that six strains had an unidentifiable O antigen.     

Diagnosis of Shiga toxin producing Escherichia coli infection, contribution of genetic amplification technique

There has been no culture method of choice for detecting non-O157 Shiga toxin-producing Escherichia coli strains (STEC) because of their biochemical diversity The aim of this study was the assessment of verotoxin gene detection (VT1/VT2) within STEC PCR compared with the Vero cells cytotoxicity among O157 and non-O157 STEC serotypes. Stool cultures were performed on Tryptic Soy Broth and sorbitol MacConkey agar with cefixitime and tellurite supplements which were identified as Escherichia coli (E. coli) by BBL crystal. Further identifications were performed including verotoxin production assessment by Vero cells cytotoxicity assay, PCR for specific VT1/VT2 genotyping, and isolates were plated on blood agar and tested for enterohemolysis. Vero cells cytotoxicity assay revealed that 58 of E. coli isolates (71.6%) were STEC. In PCR, 33 (56.9%) of the 58 strains were positive for the VT2 gene, 24 (41.4%) were positive for the VT1 gene and one isolate was positive for both genes. In comparison to Vero cells cytotoxicity, the sensitivity, specificity of PCR were 100%. In comparative study between verotoxin assessment by Vero cells cytotoxicity and enterohemolytic activity, concordance positive results between both were 53 (91.4%). The most common serogroups of STEC were O157 (33%) and O26 (20%). From this study we can conclude that enterohemolysin production can be used as surrogate marker for STEC. The most rapid and promising approach for detection of STEC is by molecular method.     

Examination of retail chickens and sausages in Britain for vero cytotoxin-producing Escherichia coli

Samples from chickens and pork sausages were examined for the presence of Vero cytotoxin-producing Escherichia coli by using DNA probes for the Vero cytotoxin genes. Hybridization was detected in 25% of the 184 sausage samples, but none of the chickens was positive. No E. coli O157:H7 strains were isolated, and serotyping showed that the Vero cytotoxin-producing E. coli strains belonged to eight different O serogroups and that six strains had an unidentifiable O antigen.     

Prevalence of Shiga Toxin-Producing Escherichia coli in a Diarrheagenic Tunisian Population, and the Report of Isolating STEC O157:H7 in Tunis

In Mellassine (a major city in the state of Tunis) and Ben Arous state (south east of Tunis), a total of 212 stool samples were collected from children and adults (symptomatic and asymptomatic groups) between November 2001 and November 2004. Three hundred and twenty-seven E. coli strains were isolated and studied, to look for shiga toxin-producing Escherichia coli (STEC) strains, which were further analysed to investigate and determine clonal relationship among Tunisian STEC strains isolated from different sources (diarrheal cases and food products). They were analysed to characterize their serotypes, virulence genes by PCR, cytotoxic effect on Vero cell, plasmid profiles, and pulsed-field gel electrophoresis (PFGE) patterns. Eleven isolates (10 nontypeable, one O157:H7) carried stx gene and shared Stx restriction fragment length polymorphism (RFLP) patterns (stx1 ( + ), stx2 ( + )). Seven of these strains were isolated from acute diarrheal cases, and four were isolated from a control group (among which the only isolated STEC O157:H7). Two of the STEC strains harboured both eae and ehxA genes. Analysis of the cytotoxic effect on Vero cells showed that a correlation exists between carrying stx1 ( + ), stx2 ( + ) genes and cytotoxicity. Also a correlation was noticed between STEC strains recovered from different sources regarding plasmid profiles and PFGE patterns. All stool samples positive for STEC were nonbloody. None of the STEC-positive patients developed severe diseases. These data demonstrate that although STEC is not a major cause of acute diarrhea in Tunis, it should not be overlooked. Measures should be taken to improve the detection and isolation of STEC from acute diarrheal cases as well as carriers.     

Lactate dehydrogenase release assay from Vero cells to distinguish verotoxin producing Escherichia coli from non-verotoxin producing strains

The Vero cell assay presently used for virulence testing of verotoxigenic Escherichia coli (VTEC) requires at least 48-96 h where cytotoxicity effects are examined under a microscope. Here, a complimentary rapid assay was developed that measures endogenous lactate dehydrogenase (LDH) release from Vero or HEp-2 cells as an indicator of cytotoxicity. Toxin preparations from 24 VTEC strains induced 36-89% LDH from Vero cells and 15-62% LDH from HEp-2 cells in 12-16 h. A verotoxin-positive but enterohemolysin negative strain also showed a similar cytotoxicity effect. In contrast, three VT-negative strains caused only 13-16% LDH from Vero cells and 1-7% LDH from HEp-2 cells. Five presumptive E. coli isolates from naturally contaminated food and clinical sources did not induce significant LDH release from either cell lines. PCR analysis confirmed the presence of vt1 or vt2 genes in E. coli showing positive LDH values. Similarly, RiboPrinter analysis confirmed and identified the test strains as E. coli except for two meat isolates, which were identified as Hafnia alvei. Cytopathic effects of toxin preparations from VTEC revealed severe lysis, vacuole formation and death in Vero cells and multiple vacuoles and cell elongation in HEp-2 cells. The colorimetric cytotoxicity assay described here can provide quantitative data for determining the virulence potential of verotoxigenic E. coli in 12-16 h.     

Molecular cloning and nucleotide sequence of another variant of the Escherichia coli Shiga-like toxin II family

Escherichia coli strain H.I.8 (O128:B12) produces low levels of a Shiga-like toxin (SLT) which we have called SLTIIva because of its close relationship with SLTIIv. The Vero cell cytotoxicity of SLTIIva is neutralized by antisera against SLTII and SLTIIv but not by antisera against SLTI. These data indicate that the SLT of strain H.I.8 is a member of the SLTII family. Since SLTIIva shares with SLTIIv the property of having low cytotoxicity to HeLa cells compared with Vero cells, it is appropriate to consider both toxins as variants of SLTII. SLTIIva differs from SLTIIv in that it is more heat-stable. Further, SLTIIv-producing strains of E. coli have only been isolated from pigs while the SLTIIva-producing E. coli strain examined in this study was isolated from a human infant with diarrhoea. The genes for this SLT were cloned from a cosmid library of total cellular DNA by screening recombinants for Vero cell toxicity and with a DNA probe derived from SLTIIv structural genes. Nucleotide sequence analysis was performed on a 2.0 kb AvaII-HincII fragment which encodes the toxin gene. The nucleotide sequence data confirm the close relationship between SLTIIva and SLTIIv: they have 98% nucleotide sequence homology in the B subunit gene and 70.6% homology in the A subunit gene. Comparison of DNA sequences indicated that SLTIIva was most closely related to SLTIIv, closely related to SLTII and less closely related to SLTI.