内蒙古西伯利亚棘球绦虫和多房棘球绦虫泡状蚴在小白鼠发育成熟的比较

本文报道人兽共患的泡状肝包虫病原,西伯利亚棘球绦虫Echinococcus sibiricensis (Rausch andSchiller, 1954)泡状蚴和多房棘球绦虫Ech inococcusmultilocularis ( Leuckart, 1863)泡状蚴在KM株小白鼠发育成熟过程比较观察的结果.此两虫种泡状蚴的发育成熟过程仍然和它们早期发育的规律(唐崇惕等,2001)相同.虽然它们成熟的泡囊都被着生在网状结构中的许多原头节所充满,但是在多房棘球绦虫9-14个月的泡状蚴,仍然可以见到它们的原头节和网状结构都是起源于泡囊囊壁内表面的胚细胞层,并且始终保持与该层的联系.而西伯利亚棘球绦虫泡状蚴在鼠肺脏或肝脏的各泡囊中的原头节和网状结构是由可移动的胚细胞团发育生成,它们与泡囊囊壁没有如前者样的联系.西伯利亚棘球泡状蚴在各别小白鼠肝脏也能发育成熟,但不正常,宿主反应异常强烈.     

宠物与肝包虫病

棘球绦虫寄生于犬科动物的小肠内,其幼虫棘球蚴寄生在动物和人的肝脏,该病严重危害人类和动物健康,对公共卫生造成了严重威胁。本文对包虫病的类型、危害、流行情况以及防治进行综述,希望有助于社会对该病正确的认识、深入的研究和对疾病的防治工作。     

包虫病防治研究进展

包虫病(又称棘球蚴病)是一种具有地方流行性和自然疫源性的人畜共患性寄生虫病,严重危害广大牧区的人民身体健康并阻碍畜牧业经济的发展.近年来,关于包虫病化疗药物的研究取得了很大进展;免疫预防是防止包虫病流行的比较理想的途径;利用现代分子生物学技术对棘球蚴绦虫的有效免疫原成份进行筛选和克隆,制备基因工程疫苗,为包虫病的免疫预防和免疫诊断开辟了新途径.本文就近年来各国对本病的防治概况作如下综述及展望,并简要分析其优势与意义.     

核酸疫苗pcDNA3.1-EG95的构建及在绵羊胎儿成纤维细胞中的表达

克隆细粒棘球蚴EG95基因cDNA并构建核酸疫苗pcDNA3.1-EG95。根据GenBank中细粒棘球蚴EG95基因序列(AF134378)设计引物并在上游引物起始密码子前加上Kozak序列(CCACC),提取细粒棘球蚴总RNA,RT-PCR扩增目的基因EG95cDNA,扩增片段克隆到pcDNA3.1(+)中构建重组载体pcDNA3.1-EG95后测序。重组质粒pcDNA3.1-EG95采用脂质体法转染绵羊胎儿成纤维细胞并用G418筛选,RT-PCR检测稳定转染细胞中目的基因的转录。测序结果表明克隆的目的基因包含了471bp的完整ORF并与载体连接正确。RT-PCR检测表明EG95基因在稳定转染的绵羊胎儿成纤维细胞中得到转录。成功构建pcDNA3.1-EG95核酸疫苗并可在绵羊胎儿成纤维细胞中转录目的基因,可进一步用于活体动物免疫研究。     

病原生物学专业研究生综合素质培养的探讨

病原生物学是基础医学中一门重要学科,高素质病原生物学人才培养,是适应社会发展、满足社会需求、促进创新型人才建设的关键.作者在实际工作中,注重引导学生学习态度和思维模式的转变,开展多种形式的教学,从学习态度、科研能力、协作能力等方面对病原生物学专业研究生综合素质的培养进行了初步的探讨,把研究生带到知识前沿、形成研究问题、引导批判和创新,使研究生掌握一定的科研思路与科研方法;注重动手能力的训练,严格施教,加强学术道德教育,探索高素质病原生物学研究生培养的新模式.     

小鼠包虫病动物模型的建立

[目的]人工感染法建立包虫病动物模型。[方法]将藏羊源细粒棘球绦虫原头蚴悬液1ml(每ml悬液含4000个原头蚴,青霉素1000U,链霉素1000U)注射于50只(25♂♂25♀♀)4周龄ICR小鼠腹腔内,每周测体重与腰围1次;设空白对照组10只(5♂♂5♀♀)。[结果]接种第20天后,动物体重和腰围均高于空白对照组的各项指标;第90天剖检动物,包囊生成率为96%(48/50),人工感染成功率为96%。[结论]绵羊源性细粒棘球绦虫原头蚴悬液腹腔注射ICR小鼠建立包虫病动物模型的方法可为包虫病的防制研究工作提供简便、可靠和实用的实验动物模型。     

新书介绍：病原真菌生物学研究与应用

由长期致力于医学真菌学临床与基础研究的廖万清、吴绍熙两位教授主编的《病原真菌生物学研究与应用》是“病原生物学丛书”之一,将于2006年9月由化学工业出版社正式出版。     

犬恶丝虫病病原生物学研究进展

从虫体的分类、分布、宿主、发育生物学和内共生体等几个方面综述了近年来在犬恶丝虫病病原生物学研究上取得成果,并提出了研究该病病原的现实意义和今后研究的主要方向.     

病原生物学实验教学中应用多学科整合及虚拟实验的探索

病原生物学作为一门实践性很强的学科,其实验教学在其中发挥重要的作用。为了提高病原生物学实验的系统性和可操作性,结合微生态学、医学微生物学及免疫学各自学科特点,进行以"抗生素诱导的肠道菌群失调"为例探讨病原生物学整合实验。由于临床标本及实验条件的限制,采用可视化虚拟实验进行消化性溃疡中病原菌分离与鉴定及微生态菌群分析实验。这将为病原生物学实验教学的改革提供相应参考。     

棘球蚴囊液对小鼠脾细胞IL-17及Smad2表达的影响

目的:观察细粒棘球蚴囊液对体外培养BALB/c小鼠脾细胞白介素(IL)-17和Smad2基因表达的影响.方法:制备小鼠脾细胞悬液,接种于48孔培养板中进行培养,以不加任何干预为对照组,囊液处理组为实验组.定时取样提取总RNA,经反转录成cDNA后用实时荧光定量PCR(qRT-PCR)检测IL-17和Smad2基因的表达.结果:小鼠脾细胞IL-17表达在囊液处理6h和12h后升高(1.000±0.207 VS 3.672±0.746和1.000±0.154 VS 5.525±0.843),差异有统计学意义(P＜0.05);小鼠脾细胞Smad2表达在培养1h后升高(1.000±0.077 VS 2.069±0.098)在12h后降低(1.000±0.110 VS 0.247±0.011),差异有统计学意义(P＜0.05);协同分析发现IL-17基因与Smad2基因的表达变化呈现负相关(P＜0.01),相关系数r=-1.结论:细粒棘球蚴囊液对小鼠脾细胞IL-17和Smad2基因的表达具有上调作用,推测其可能与宿主抗棘球蚴感染的机制有关.     

Here,there, and everywhere: How pathogenic Escherichia coli sense and respond to gastrointestinal biogeography

Gastrointestinal (GI) pathogens enteropathogenic and enterohaemorrhagic Escherichia coli (EPEC and EHEC), and related mouse pathogen Citrobacter rodentium, are referred to as attaching and effacing (AE) pathogens for the lesions they form upon colonisation of the host epithelium. EPEC, EHEC, and C. rodentium are well known to use a type III secretion system to intimately attach to intestinal cells and secrete bacterial effectors to manipulate host cell processes. Less well known is the ability of AE pathogens to overcome significant physiological and microbial barriers and target specific gut niches for initial colonisation of the host epithelium. This review considers recent work highlighting the biogeography of the GI tract as it applies to colonisation by enteric pathogens, including environmental barriers to enteric infection, signals sensed by AE pathogens for navigation of the GI tract, and the tools AE pathogens use to respond to the changing host environment.     

Identification of genetic loci affecting the establishment and development of Echinococcus multilocularis larvae in mice

Alveolar echinococcosis (AE) is a severe hepatic disorder caused by larval infection by the fox tapeworm Echinococcus multilocularis. The course of parasitic development and host reactions are known to vary significantly among host species, and even among different inbred strains of mice. As reported previously, after oral administration of parasite eggs, DBA/2 (D2) mice showed a higher rate of cyst establishment and more advanced protoscolex development in the liver than C57BL/6 (B6) mice. These findings strongly suggest that the outcome of AE is affected by host genetic factor(s). In the present study, the genetic basis of such strain-specific differences in susceptibility/resistance to AE in murine models was studied by whole-genome scanning for quantitative trait loci (QTLs) using a backcross of (B6 × D2)F₁ and D2 mice with varying susceptibility to E. multilocularis infection. For cyst establishment, genome linkage analysis identified one suggestive and one significant QTL on chromosomes (Chrs.) 9 and 6, respectively, whereas for protoscolex development, two suggestive and one highly significant QTLs were detected on Chrs. 6, 17 and 1, respectively. Our QTL analyses using murine AE models revealed that multiple genetic factors regulated host susceptibility/resistance to E. multilocularis infection. Moreover, our findings show that establishment of the parasite cysts in the liver is affected by QTLs that are distinct from those associated with the subsequent protoscolex development of the parasite, indicating that different host factors are involved in the host–parasite interplay at each developmental stage of the larval parasite. Further identification of responsible genes located on the identified QTLs could lead to the development of effective disease prevention and control strategies, including an intensive screening and clinical follow-up of genetically high-risk groups for AE infection.     

Alveolar epithelial type II cell: defender of the alveolus revisited

In 1977, Mason and Williams developed the concept of the alveolar epithelial type II (AE2) cell as a defender of the alveolus. It is well known that AE2 cells synthesise, secrete, and recycle all components of the surfactant that regulates alveolar surface tension in mammalian lungs. AE2 cells influence extracellular surfactant transformation by regulating, for example, pH and [Ca²⁺] of the hypophase. AE2 cells play various roles in alveolar fluid balance, coagulation/fibrinolysis, and host defence. AE2 cells proliferate, differentiate into AE1 cells, and remove apoptotic AE2 cells by phagocytosis, thus contributing to epithelial repair. AE2 cells may act as immunoregulatory cells. AE2 cells interact with resident and mobile cells, either directly by membrane contact or indirectly via cytokines/growth factors and their receptors, thus representing an integrative unit within the alveolus. Although most data support the concept, the controversy about the character of hyperplastic AE2 cells, reported to synthesise profibrotic factors, proscribes drawing a definite conclusion today.     

Alveolar epithelial type II cell: defender of the alveolus revisited

In 1977, Mason and Williams developed the concept of the alveolar epithelial type II (AE2) cell as a defender of the alveolus. It is well known that AE2 cells synthesise, secrete, and recycle all components of the surfactant that regulates alveolar surface tension in mammalian lungs. AE2 cells influence extracellular surfactant transformation by regulating, for example, pH and [Ca²⁺] of the hypophase. AE2 cells play various roles in alveolar fluid balance, coagulation/fibrinolysis, and host defence. AE2 cells proliferate, differentiate into AE1 cells, and remove apoptotic AE2 cells by phagocytosis, thus contributing to epithelial repair. AE2 cells may act as immunoregulatory cells. AE2 cells interact with resident and mobile cells, either directly by membrane contact or indirectly via cytokines/growth factors and their receptors, thus representing an integrative unit within the alveolus. Although most data support the concept, the controversy about the character of hyperplastic AE2 cells, reported to synthesise profibrotic factors, proscribes drawing a definite conclusion today.     

Echinococcosis in China,a Review of the Epidemiology of <Emphasis Type="Italic">Echinococcus</Emphasis> spp.

Cystic echinococcosis (CE) and alveolar echinococcosis (AE) are highly significant infectious diseases occurring worldwide and caused by metacestodes of tapeworms Echinococcus granulosus and E. multilocularis, respectively. Both human CE and AE have highest prevalence rates in western and northwestern China. Livestock is the main intermediate host of E. granulosus, and wild small mammal are the main intermediate hosts of E. multilocularis. Since they range freely in pastoral areas, prey on wild small mammals and offal of livestock after slaughter, and have close relationships with humans, domestic dogs are the most important definitive host of both Echinococcus spp. with the highest risk of transmitting CE and AE to humans. Pastoralism is the occupation with the highest risk of being infected with the both kinds of echinococcosis due to the proximity of livestock, dogs, and wildlife host species. In this review, we summarize the epidemiology of human echinococcosis, the situation of parasite transmission in animal hosts, and possible transmission patterns in China. In addition, human activities and their potential influence on the transmission of echinococcosis are also discussed.     

Identification of Staphylococcus aureus virulence genes in a murine model of bacteraemia using signature-tagged mutagenesis

Attaching and effacing (AE) bacteria are a diverse group of gastrointestinal pathogens, comprising members of four genera, that cause the intestinal epithelial microvilli to be replaced with raised clusters of filamentous actin that conform to the surface of attached bacteria. We have cloned a 35.4 kb 'pathogenicity island' from the prototype AE bacterium, enteropathogenic Escherichia coli , containing all previously described AE genes. Transfer of this pathogenicity island to avirulent E. coli converts the recipients into strains that secrete virulence proteins, induce host signal-transduction pathways, and cause AE lesions on cultured epithelial cells. These results demonstrate that this pathogenicity island contains all pathogen-specific genes necessary for inducing AE lesions, and that the defining feature of this class of pathogens can be acquired by an avirulent bacterium in a single genetic step.     

Drivers of Echinococcus multilocularis Transmission in China: Small Mammal Diversity,Landscape or Climate?

Background

Human alveolar echinococcocosis (AE) is a highly pathogenic zoonotic disease caused by the larval stage of the cestode E. multilocularis. Its life-cycle includes more than 40 species of small mammal intermediate hosts. Therefore, host biodiversity losses could be expected to alter transmission. Climate may also have possible impacts on E. multilocularis egg survival. We examined the distribution of human AE across two spatial scales, (i) for continental China and (ii) over the eastern edge of the Tibetan plateau. We tested the hypotheses that human disease distribution can be explained by either the biodiversity of small mammal intermediate host species, or by environmental factors such as climate or landscape characteristics.

Methodology/findings

The distributions of 274 small mammal species were mapped to 967 point locations on a grid covering continental China. Land cover, elevation, monthly rainfall and temperature were mapped using remotely sensed imagery and compared to the distribution of human AE disease at continental scale and over the eastern Tibetan plateau. Infection status of 17,589 people screened by abdominal ultrasound in 2002–2008 in 94 villages of Tibetan areas of western Sichuan and Qinghai provinces was analyzed using generalized additive mixed models and related to epidemiological and environmental covariates. We found that human AE was not directly correlated with small mammal reservoir host species richness, but rather was spatially correlated with landscape features and climate which could confirm and predict human disease hotspots over a 200,000 km² region.

Conclusions/Significance

E. multilocularis transmission and resultant human disease risk was better predicted from landscape features that could support increases of small mammal host species prone to population outbreaks, rather than host species richness. We anticipate that our study may be a starting point for further research wherein landscape management could be used to predict human disease risk and for controlling this zoonotic helminthic.     

The DNase of gammaherpesviruses impairs recognition by virus-specific CD8+ T cells through an additional host shutoff function

The DNase/alkaline exonuclease (AE) genes are well conserved in all herpesvirus families, but recent studies have shown that the AE proteins of gammaherpesviruses such as Epstein-Barr virus (EBV) and Kaposi's sarcoma-associated herpesvirus (KSHV) exhibit an additional function which shuts down host protein synthesis. One correlate of this additional shutoff function is that levels of cell surface HLA molecules are downregulated, raising the possibility that shutoff/AE genes of gammaherpesviruses might contribute to viral immune evasion. In this study, we show that both BGLF5 (EBV) and SOX (KSHV) shutoff/AE proteins do indeed impair the ability of virus-specific CD8+ T-cell clones to recognize endogenous antigen via HLA class I. Random mutagenesis of the BGLF5 gene enabled us to genetically separate the shutoff and AE functions and to demonstrate that the shutoff function was the critical factor determining whether BGLF5 mutants can impair T-cell recognition. These data provide further evidence that EBV has multiple mechanisms to modulate HLA class I-restricted T-cell responses, thus enabling the virus to replicate and persist in the immune-competent host.     

Immunoproteomic assay of extracellular proteins in Streptococcus equi ssp. zooepidemicus

A proteomic approach combining two-dimensional electrophoresis, Western blot and matrix-assisted laser desorption tandem time-of-flight mass spectrometry has been used to map the extracellular proteins of Streptococcus equi ssp. zooepidemicus ( S . zooepidemicus ) strain ATCC 35246. These bioinformatic technologies facilitated the identification of novel S . zooepidemicus vaccine candidate antigens and therapeutic agents. Despite the limitations posed by the unavailability of complete genome and proteome data for S . zooepidemicus , seven of 15 chosen immunogenic spots were successfully identified as streptococcal proteins (AE1 and AE4 c . 10) from homologous Streptococcus species. Among these, AE6 and AE7 were identified as S . zooepidemicus UDP- N -acetyl-glucosamine pyrophosphorylase and UDP-glucose pyrophosphorylase proteins. In addition, AE4 was determined to be glyceraldehyde-3-phosphate dehydrogenase from Enterococcus faecalis . Following signalip 3.0 ( http://www.cbs.dtu.dk/servicess/SignalIP ) prediction, data suggested that AE5, AE7 and AE9 contained signal peptides. blast ( http://www.sanger.ac.uk ) results found that nucleotide sequences of all identified proteins shared high homology (≥65%) with S. zooepidemicus . The majority of proteins identified in our study remain formally unreported in S. zooepidemicus . However, these proteins serve a vital role in the immune system and reproduction of host species. Therefore, we further evaluated the proteins as vaccine candidates in this study.