湖南长沙及湘西泡状带绦虫分离株线粒体cox1基因的克隆及序列分析

目的研究湖南省长沙及湘西泡状带绦虫分离株线粒体细胞色素C氧化酶第1亚基（cox1）基因部分序列（pcox1）的遗传变异情况,并用peox1序列重构泡状带绦虫与其他带科绦虫的种群遗传关系。方法应用聚合酶链反应（PCR）扩增泡状带绦虫虫株的pcox1,应用Clusta1X1．81程序对序列进行比对。然后用Phylip3．67程序MP法和Mage4．0程序NJ法绘制种系发育树,并用Puzzle5．2程序构建最大似然树;同时利用DNAstar5．0中的Megalign程序进行同源性分析,并与GenBank^TM中已知泡状带绦虫相应基因序列进行比较分析。结果所获得的pcox1序列长度一致,均为343bp,与GenBank^TM公布的带科绦虫序列进行比较分析表明,湖南长沙分离株1和湘西分离株5与已知泡状带绦虫相应基因的相似性分别为99．4％和99．7％,与其它带科绦虫的相似性均小于90．0％;湖南长沙1和湘西分离株5与已知泡状带绦虫相应基因遗传距离分别为0．006和0．003,与其他带科绦虫的遗传距离均大于0．100。种系发育树表明,2个分离株与已知泡状带绦虫位于同一分枝,Bootstrap值在97％以上。结论由于泡状带绦虫pcox1序列种内相对保守,种问差异较大,故可作为种间遗传变异研究的标记,研究结果为进一步研究泡状带绦虫的群体遗传结构奠定了基础。     

三峡库区上、下游血吸虫病流行区钉螺线粒体cox1基因遗传变异研究

目的研究三峡库区上、下游血吸虫病流行区钉螺线粒体DNA细胞色素C氧化酶亚单位t（c毗1）基因的遗传变异。方法采集三峡库区上游四川、云南及下游安徽、湖北4省共7个地、市的钉螺样本,提取基因组DNA,PCR特异性扩增线粒体cox1基因并测序,用ClustalX（1．81）软件进行多序列比对,MEGA（4．0）软件Kimura2-parameter法计算遗传距离,邻接法（NJ）和最大简约法（MP）构建系统发生树。结果上游与下游不同地域株钉螺间cox1基因差异约为16％．下游地区的肋壳与光壳钉螺cox1基因差异约为3．7％,上游不同地域株钉螺碱基差异约为5．4％。遗传距离显示,上游四川与云南地域株的遗传距离为0．022～0．050,下游安徽与湖北地域株的遗传距离为0．014～0．027,而上游与下游各地区螺群间的遗传距离在0．127～0．138之间,明显大于上游或下游各地区螺群内的遗传距离。进化树结果表明,下游湖北的荆州、石首和安徽的芜湖、宁国钉螺形成一支系,上游四川的绵竹、新都钉螺同属一支系。但两种方法构建的进化树在云南大理钉螺的归属上存在差异,MP法提示大理钉螺从上游的分支中独立出来,单独形成一类。结论上游与下游不同地域株钉螺cox1基因遗传差异较显著,下游肋壳和光壳钉螺种群内遗传变异较小,而上游光壳钉螺种群内遗传变异较大。     

弓形虫缓殖子期特异抗原SAG2C基因的克隆、鉴定与生物信息学分析

目的克隆并鉴定弓形虫PRU株表面抗原SAG2C基因序列和cDNA序列，对比不同毒力弓形虫株（PRU、RH、ME49）中SAG2C基因序列。进行生物信息学分析。方法根据SAG2C基因已知序列设计合成一对引物，应用PCR技术从Prugniaud（PRU）株弓形虫基因组DNA和总RNA中扩增SAG2C基因，克隆入pMD19-T载体并进行序列测定。应用DNAMAN软件、NCBI网站（http：／／www。ncbi．nlm．nih.gov／）分析3种虫株之间SAG2C基因的同源性；利用生物信息学网站ExPASy（http：／／us.expasy．org／）对获得的基因及推导出的氨基酸序列进行生物信息学分析。结果PCR扩增得到弓形虫PRU株SAG2C基因及其全长cDNA序列．酶切及PCR鉴定获得了正确的重组质粒。测序结果表明，获得SAG2C基因序列1225bp，全长cDNA序列1095bp，编码364个氨基酸。同源性分析显示。弓形虫Prugniaud株和RH株SAG2C基因同源性为97．14％；Prugniaud株与ME49株cDNA序列同源性为96．89％；编码氨基酸序列同源性为92％。N端为信号肽，C端疏水序列预测它为糖基磷脂酰肌醇固着蛋白．存在13个潜在抗原表位及多个保守功能区域。结论成功克隆了弓形虫缓殖子期特异抗原SAG2C基因序列及其全长cDNA序列。序列分析显示其为糖基磷脂酰肌醇固着蛋白。     

湖南省日本血吸虫线粒体cox1基因部分序列多态性的研究

目的研究湖南省日本血吸虫不同自然隔离群的线粒体细胞色素c氧化酶亚基1基因（coxl）部分序列（pcoxl）的变异，为阐明我国日本血吸虫的种群遗传结构奠定基础。方法采用聚合酶链反应（PCR）技术对湖南省岳阳君山、汨罗的日本血吸虫的pcoxl片段进行扩增、克隆及序列分析。结果获得480bp的pcoxl序列。经DNAstar软件分析，pcoxl序列有一定的种内差异（0～1．2％）。结论本研究为阐明我国日本血吸虫的种群遗传结构提供了数据。     

蓝氏贾第鞭毛虫基因分型—磷酸丙糖异构酶(tim)基因序列分析

蓝氏贾第鞭毛虫（简称贾第虫）细胞内的磷酸丙糖异构酶（ｔｉｍ）基因编码磷酸丙糖异构酶。对扩增后的ｔｉｍ基因做序列分析，可对来源于不同地理位置和／或不同宿主的贾第虫株进行基因分型，并以此确定它们之间的遗传学关系。为了确定中国虫株的基因型，我们对分离自北京（Ｃ１），四川（Ｃ２）和福建（Ｃ３）３株人源贾第虫ｔｉｍ基因序列进行了分析。结果表明，Ｃ１和Ｃ２具有相同的遗传学特性，可划归为目前公认的分型系统中的第３型（ＧＳ）。Ｃ３含有两种不同的遗传学类型，即第１型（ＷＢ）和第３型（ＧＳ），表明Ｃ３可能为两种不同遗传学类型的混合株。本研究结果进一步表明，用ｔｉｍ基因扩增和序列分析方法，可探寻世界范围内贾第虫株之间的遗传学关系。     

恶性疟原虫海南株裂殖子表面蛋白1基因第1至第4区的多态性分析

本对5株恶性疟原虫海南株MSP1基因5'端（第1～第4区）进行体外扩增，其中2株的目的基因扩增产物直接用末端标记循环测序法测定其DNA序列，另3株虫株的目的基因片段用pGEM-T载体克隆化后再测序，结果获得了6个MSP1分子第1～第4区的序列片段，与已报告的MSP1分子比较，证明属MAD20等位基因型。同时发现，6个序列片段中，除了HN3和HN5株的序列彼此完全一致，其余株序列的保守区（第1和第3区）也一致外，可变区的第2区和第4区的氨基酸序列存在一定的差异，与MAD20的序列也略有不同，序列分析也证明海南株的MSP1也存在基因内重组现象，此外，3株经克隆化处理的虫株中，发现1株含2种不同的MSP1等位基因，本研究初步提供了我国恶性疟原虫海南株MSP1存在多态性的依据。     

蓝氏贾第鞭毛虫基因分型—磷酸丙糖异构酶（tim）基因序列 …

蓝氏贾第鞭毛虫（简称贾第虫）细胞内的磷酸丙糖异构酶（ｔｉｍ）基因编码磷酸丙糖异构酶。对扩增后的ｔｉｍ基因做序列分析，可对来源于不同地理位置和／或不同宿主的贾第虫株进行基因分型，并以此确定它们之间的遗传学关系。为了确定中国虫株的基因型，我们对分离自北京（Ｃ１），四川（Ｃ２）和福建（Ｃ３）３株人源贾第虫ｔｉｍ基因序列进行了分析。结果表明，Ｃ１和Ｃ２具有相同的遗传学特性，可划归为目前公认的分型系统中的第     

弓形虫HT分离株ROP5蛋白基因的克隆、序列分析及其表达研究

目的克隆和表达弓形虫虎源分离株（HT株）ROP5蛋白基因。方法运用RT—PCR技术从弓形虫HT株中扩增出ROP5基因，将其克隆人T载体中进行测序和分析．并将目的基因亚克隆到大肠杆菌表达载体pET28a中进行诱导表达。结果该基因全长1650bp，编码549个氨基酸。其中前24个氨基酸构成信号肽序列。与GenBank中报道的RH株相比，有12个核苷酸有差异，导致7个氨基酸发生改变，两者核苷酸和推导氨基酸序列的同源性分别为99．2％和98．9％。转化重组质粒pETROP5的大肠杆菌BL21（DE3）在IPTG的诱导下，可表达出相对分子质量为64800的重组蛋白，并且能与弓形虫抗体发生血清学反应，表达量占菌体蛋白的15．6％。结论成功克隆和表达了弓形虫HT株ROP5蛋白基因，表达的重组蛋白具有良好的反应原性。     

新成人腹泻轮状病毒J19株NSP1、NSP2和NSP3基因序列分析

目的 克隆新成人腹泻轮状病毒J19株三个非结构蛋白NSP1、NSP2和NSP3基因，并分析其基因序列。方法 利用一种改进的非依赖核酸序列的单引物扩增方法扩增J19株三个基因，克隆到pMD18-T载体中并进行测序。在此基础上，将J19株的NSP1、NSP2和NSP3的蛋白序列与其他轮状病毒蛋白序列进行比较分析和种系进化分析。结果J19株的NSP1、NSP2和NSP3基因为基因5、7和8，它们的全长1307个、1004个和932个核苷酸，编码395个、297个和262个氨基酸。与J19株的NSP1、NSP2和NSP3蛋白序列一致性较高的分别是B组轮状病毒KB63株（26．3％）、WH1株（46．6％）和IDIR株（29．6％）。对J19株的NSP1、NSP2和NSP3的遗传进化分析表明，J19株在进化树上的位置都靠近A、B和C组轮状病毒分支的根部，而且它比较偏向于B组轮状病毒的分支。结论 J19株的NSPI、NSP2和NSP3与其他轮状病毒的相应蛋白序列存在显著差异。J19株NSP1、NSP2、NSP3的蛋白序列比较和遗传进化分析表明新成人腹泻轮状病毒与成人腹泻轮状病毒可能有共同起源；但是新成人腹泻轮状病毒与成人腹泻轮状病毒存在显著差异。     

中国百日咳疫苗生产株S1和Prn蛋白基因序列分析

目的了解我国百日咳疫苗生产株百日咳毒素S1和外膜蛋白（Prm）的基因特征。方法分别克隆疫苗株的S1和Prn基因至PGEM-Teasy载体、进行测序，并与GenBank中收录的百日咳杆菌S1和Prn蛋白基因序列进行比较、分析。结果完成了3株疫苗生产株S1和Prn基因的扩增、克隆和序列测定。序列分析显示3疫苗株间的S1和Prn基因核苷酸序列和氨基酸序列同源性均在99％以上，基因进化树显示与其他菌株的同源性也较高。结论对我国3株疫苗生产株S1和Prn基因序列进行了详细地分析，为我国百日咳流行病学的研究和疫苗的质量控制、研制奠定了基础。     

用重组SAG1抗原检测弓形虫抗体

目的探讨重组SAG1抗原对弓形虫IgG和IgM抗体的检测效果。方法用rSAG1作抗原建立免疫印迹方法（rSAG1-WB）,与玻片虫体过氧化物酶免疫染色试验（TSHE）平行检测不同来源血清。结果15例病原学检查阳性小鼠血清和5例免疫兔血清的IgG抗体均为阳性,30例正常小鼠血清和10例正常兔血清均未出现阳性反应。rSAG1-WB检测可疑弓形虫病患者血清阳性率为60．3％（38／63）,献血员血清阳性率为6％（3／50）,与TSHE检测结果（65．1％和4％）均无统计学差异（P〉0．05）。1例IgM强阳性血清和13例IgM弱阳性血清在Western—blot检测中分别出现相应的强阳性与弱阳性反应,50例献血员血清均未出现IgM阳性反应,结果与TSHE一致。结论rSAG1-WB检测弓形虫IgG和IgM抗体均具有高度的敏感性和特异性．与TSHE的符合率高。     

Genetic control of murine resistance to Toxoplasma gondii.

The genetics of murine susceptibility to Toxoplasma gondii was investigated in inbred mice and their F1 and F2 offspring. Among four strains of congenic mice of the B10 background, those with H-2a/a and H-2b/b genotypes were more susceptible than were those with H-2d/d and H-2k/k genotypes. Breeding studies utilizing three of these strains demonstrated linkage between the H-2a allele and greater susceptibility. These data suggest the existence of an H-2-linked gene affecting susceptibility to T. gondii. In challenge of recombinant inbred mice derived from C57Bl/6J (high susceptibility) and BALB/c (low susceptibility) strains, lines BE, BJ, and BK were more susceptible than lines BD, BG, BH, and BI. These data are consistent with the existence of a second disease susceptibility gene linked to the H-13 locus. F1 offspring of the C57B1/6J X B10.D2 mice were significantly less susceptible than either parent. This phenotypic complementary suggests the presence of more than one genetic mechanism of resistance to T. gondii. From these combined data, we conclude that (i) susceptibility to T. gondii in mice is affected by at least two genes, (ii) one of the genes is linked to the H-2 and one to the H-13 locus, and (iii) more than a single mechanism of resistance must be considered to explain the observed genetic controls of susceptibility.     

Acute virulence in mice is associated with markers on chromosome VIII in Toxoplasma gondii.

Toxoplasma gondii has an unusual population structure consisting of three widely distributed clonal lineages. Acute virulence in mice is strictly observed in type I strains, indicating that a genetic determinant(s) unique to this lineage controls acute pathogenesis. We have analyzed several naturally occurring recombinant strains of T. gondii that carry allele 1 at the SAG1 locus; this allele is characteristic of the type I strains and was previously found to be 100% correlated with the acute virulence phenotype. Recombinant strains G622-M and ROD both had a predominantly type III genotype, with the significant exception of allele 1 at the SAG1 locus. Although these two strains had virtually identical multilocus genotypes, they differed in their virulence in mice. Strain ROD was virulent whereas strain G622-M was nonvirulent, thus demonstrating that the presence of allele 1 at SAG1 is not alone sufficient to confer acute virulence. Several sequence polymorphisms upstream of SAG1 were found to be highly correlated with the acutely virulent lineages. Collectively, these results suggest that acute virulence is regulated by a region linked to the SAG1 locus on chromosome VIII in T. gondii.     

弓形虫依钙蛋白激酶Calpain—like基因的克隆及表达

目的克隆弓形虫RH株Calpain—like基因片段，构建原核表达载体，诱导表达Calpain-like基因重组蛋白。方法收集、纯化弓形虫RH株速殖子，提取总RNA，在设计合成的引物中引入SalI和EcoRI酶切位点。应用FIT—PCR扩增弓形虫RH株Calpain—like基因片段，插入pGEM—T载体，提取重组质粒，双酶切获得目的基因，亚克隆到原核表达质粒pET32a，重组子经双酶切、PCR和DNA序列分析鉴定，转化大肠杆菌BL21并以IPTG诱导表达。结果从弓形虫RH株速殖子eDNA中扩增出316bp的Calpain-like基因片段；含pET32a／Calpain—like的重组质粒在宿主菌经诱导后，获得与预期分子量相符的表达产物。结论成功地克隆和表达弓形虫RH株Calpain—like基因，弓形虫Calpain—like基因的克隆表达为进一步筛选弓形虫疫苗候选分子和治疗药物的靶位提供了研究基础。     

Toxoplasma gondii: prevalence and characterization of new genotypes in free-range chickens from south Brazil

Parasitology Research - Toxoplasma gondii is an intracellular parasite that can infect all warm-blooded animals including humans. Recent studies showed that T. gondii strains from South America are...     

Gamma interferon-induced inhibition of Toxoplasma gondii in astrocytes is mediated by IGTP

Toxoplasma gondii is an important pathogen in the central nervous system, causing a severe and often fatal encephalitis in patients with AIDS. Gamma interferon (IFN-gamma) is the main cytokine preventing reactivation of Toxoplasma encephalitis in the brain. Microglia are important IFN-gamma-activated effector cells controlling the growth of T. gondii in the brain via a nitric oxide (NO)-mediated mechanism. IFN-gamma can also activate astrocytes to inhibit the growth of T. gondii. Previous studies found that the mechanism in murine astrocytes is independent of NO and all other known anti-Toxoplasma mechanisms. In this study we investigated the role of IGTP, a recently identified IFN-gamma-regulated gene, in IFN-gamma inhibition of T. gondii in murine astrocytes. Primary astrocytes were cultivated from IGTP-deficient mice, treated with IFN-gamma, and then tested for anti-Toxoplasma activity. In wild-type astrocytes T. gondii growth was significantly inhibited by IFN-gamma, whereas in astrocytes from IGTP-deficient mice IFN-gamma did not cause a significant inhibition of growth. Immunoblot analysis confirmed that IFN-gamma induced significant levels of IGTP in wild-type murine astrocytes within 24 h. These results indicate that IGTP plays a central role in the IFN-gamma-induced inhibition of T. gondii in murine astrocytes.     

Microsatellite in the beta-tubulin gene of Toxoplasma gondii as a new genetic marker for use in direct screening of amniotic fluids.

To examine the correlation between Toxoplasma gondii genotype and congenital human toxoplasmosis, the polymorphism of the microsatellite consisting of a dinucleotide (TG) repeat in the intron of the beta-tubulin gene was investigated by PCR. Thirty-four reference strains were studied, including 7 strains virulent in mice and 27 strains avirulent in mice. The seven virulent strains had a (TG)8 microsatellite, and the avirulent strains had a (TG)7 microsatellite. This confirms the dichotomy already observed for virulent and avirulent strains. Additionally, 37 samples of amniotic fluid from infected fetuses were tested. All of them had the (TG)7 microsatellite marker. This result confirms that most of the human cases of congenital toxoplasmosis are due to strains avirulent in mice. Nevertheless, their virulence in human fetuses was obvious, as numerous abnormalities were observed on ultrasonic examination. The new genetic marker is the first one directly used for typing T. gondii isolates without any bias due to cultivation of the parasite. This microsatellite marker is not sufficient to type the strains which are avirulent in mice; however, seeking more polymorphic microsatellites should be worthwhile to obtain new genetic markers for direct screening of biological samples.     

2005年湛江市、韶关市、汕头市人兽弓形虫感染状况调查

目的了解广东省湛江市、韶关市、汕头市的人兽弓形虫感染情况。方法收集3个地区人、猪、鼠血清，采用酶联免疫吸附试验（ELISA）间接法检测弓形虫IgG抗体。结果湛江市检测猪血清279份，阳性13份，阳性率为4．66％，检测鼠血清93份，阳性7份，阳性率7．53％；韶关市检测人血清42份，阳性0份，检测鼠血清95份，阳性3份，阳性率3．16％；汕头市检测人血清50份，阳性6份，阳性率为12．00％，检测鼠血清100份，阳性3份，阳性率为4．00％。结论汕头市人群存在弓形虫感染，湛江市、韶关市、汕头市兽类存在弓形虫感染，3个地区的鼠类弓形虫感染率无统计学意义，家鼠、野鼠的弓形虫感染率也无统计学意义。