Lyme borreliosis: Ten years after discovery of the etiologic agent,Borrelia burgdorferi

Summary Since the recovery of its causative agent,Borrelia burgdorferi, in 1981, Lyme borreliosis has become the most prevalent tick-borne disease in the United States as well as in Europe. Its steadily increasing clinical spectrum now includes erythema migrans, acrodermatitis chronica atrophicans, lymphadenosis beniga cutis, arthritis, myocarditis, progressive meningoencephalitis, myositis, and various ocular and skin disorders. The true incidence of Lyme borreliosis in the world is unknown. In the United States, it has increased from 2,000 cases in 1987, to more than 8,000 in 1989. It occurs now in regions where the tick vectors,Ixodes dammini andIxodes pacificus, are absent and where other species of ticks may be responsible for maintaining and distributing the spirochete. In Europe, Lyme borreliosis has been reported from 19 countries; its occurrence coincides with the distribution of the vector tick,Ixoides ricinus and possiblyIxodes hexagonus. Specific and dependable serological tests are still not available, but development of probes for specific antigens and the polymerase chain reaction appear promising in detecting ongoing infection and in identifyingB. burgdorferi in ticks, animal, and human hosts. Brief reference is made to advances in the preparation of whole cell and genetically engineered vaccines.

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Lyme-Borreliose: Zehn Jahre nach Entdeckung des ätiologischen Agens, Borrelia burgdorferi

Zusammenfassung Die Lyme-Borreliose ist seit der Entdeckung des kausalen ErregersBorrelia burgdorferi im Jahre 1981 die häufigste durch Zecken übertragene Krankheit in den USA und in Europa geworden. Zu ihrem immer umfangreicher werdenden klinischen Spektrum gehören Erythema migrans, Acrodermatitis chronica atrophicans, Lymphadenosis benigna cutis, Arthritis, Myokarditis, progressive Meningoenzephalitis, Myositis und verschiedene andere Störungen, die die Augen und die Haut betreffen. Über die weltweite Inzidenz der Lyme-Borreliose gibt es keine Daten. In den USA haben die Fallzahlen von 2000 im Jahr 1987 auf mehr als 8000 im Jahr 1989 zugenommen. Die Lyme Borreliose tritt jetzt in Gegenden auf, in denen die ZeckenvektorenIxodes dammini undIxodes pacificus nicht vorkommen, wo aber andere Zeckenspezies für die Persistenz und weitere Verbreitung der Spirochete verantwortlich sein können. 19 europäische Länder haben Fälle von Lyme Borreliosis mitgeteilt, dabei korreliert das Vorkommen mit der Verbreitung der ZeckenvektorenIxodes ricinus und möglicherweise auchIxodes hexagonus. Immer noch fehlt es an spezifischen und zuverlässigen serologischen Tests. Vielversprechend erscheint die Entwicklung von spezifischen Antigenproben und der Polymerasekettenreaktion Für den Nachweis einer bestehenden Infektion und die Identifizierung vonB. burgdorferi in Wirten wie Zecken, Tieren und dem Menschen. Fortschritte in der Präparation von Gesamt-Zell-Vakzinen und gentechnologisch hergestellten Vakzinen werden kurz mitgeteilt.

     

Development of polymerase chain reaction primer sets for diagnosis of Lyme disease and for species-specific identification of Lyme disease isolates by 16S rRNA signature nucleotide analysis.

We have determined and compared partial 16S rRNA sequences from 23 Lyme disease spirochete isolates and aligned these with 8 sequences previously presented. The 16S rRNA signature nucleotide compositions were defined for each isolate and compared with the genomic species signature nucleotide sets previously established. To identify positions truly indicative of species classification which could serve as targets for polymerase chain reaction species-specific identification primers, 16S rRNA-based phylogenetic analyses were conducted. On the basis of the identified signature nucleotides, we designed polymerase chain reaction primer sets which (i) amplify all spirochete species associated with Lyme disease and (ii) differentiate between these species. The primer sets were tested on 38 Borrelia isolates associated with Lyme disease and were found to be sensitive and specific. All Lyme disease isolates tested were amplification positive. These primers allow for the rapid species identification of Lyme disease isolates.     

Altered synthetic response of Campylobacter jejuni to cocultivation with human epithelial cells is associated with enhanced internalization.

Campylobacter jejuni has been shown to bind to and enter epithelial cells in culture. The interaction of C. jejuni with INT 407 epithelial cells was examined to determine whether bacterial protein synthesis is required for either binding or internalization. Chloramphenicol, a selective inhibitor of bacterial protein synthesis, significantly reduced the internalization, but not binding, of C. jejuni compared with untreated controls as determined by protection from gentamicin. Electrophoretic analysis of metabolically labeled proteins revealed that C. jejuni cultured with INT 407 cells synthesized 14 proteins that were not detected in organisms cultured in medium alone. The inhibitory effect of chloramphenicol on internalization was reduced by preincubation of C. jejuni with INT 407 cells. The results indicate that C. jejuni, like some other enteric pathogens, engages in a directed response to cocultivation with epithelial cells by synthesizing one or more proteins that facilitate internalization and suggest that this phenomenon is relevant to the pathogenesis of enteritis caused by C. jejuni.     

Laboratory confirmation of Lyme disease

Lyme disease can be confirmed in the laboratory by isolation or detection of its causative agent, a tick-borne spirochete Borrelia burgdorferi, or by a diagnostic change in the titre of antibodies specific to the agent. B burgdorferi can be isolated and cultivated in Barbour-Stoenner-Kelly II medium. It can be detected by light microscopy in tissue sections or, rarely, in blood smears using various staining methods. There is interest in the development of alternative detection methods, including identification of specific antigens of B burgdorferi in the urine of suspected cases and demonstration of the presence of species-specific DNA using polymerase chain reaction assays. Currently, serological tests (indirect immunofluorescence assay, enzyme-linked immunosorbent assay and Western immunoblot) are the most practical and available methods for confirming Lyme disease. The quest to improve the specificity and sensitivity of serological tests - for example, through the use of specific recombinant antigens - continues.     

纤恙螨属线粒体基因组研究进展

恙螨引起的恙虫病是世界上危害严重的一类人兽共患寄生虫病。本文综述现有纤恙螨属线粒体基因组信息,发现以下几个特点:纤恙螨属线粒体基因组与节肢动物以及前气门目其他物种的线粒体基因组排列发生了较大变化;红纤恙螨和地里纤恙螨有2个非编码区,苍白纤恙螨有4个非编码区;AT-偏斜为正值,但cox1第3位密码子的AT-偏斜和GC-偏斜与后生动物典型的链偏向相反;tRNA和rRNA基因的平均大小比部分寄螨总目物种要短,导致大部分tRNA基因具有非典型的二级结构。对纤恙螨属线粒体基因组的结构特征和变异情况进行比较,弥补了蜱螨亚纲线粒体基因组传统认识的不足和局限。     

厩真厉螨的研究现状

在检索、归纳和总结国内外相关文献基础上,本文综述了厩真厉螨的发现及命名、分布、生活史、致病性、流行病学意义等方面的研究现状,旨在为厩真厉螨及其传播疾病的监测和防控提供参考资料。     

我国乙型脑炎病毒血清学ELISA诊断技术研究进展

乙型脑炎是以蚊虫为传播媒介的一种自然疫源性急性传染病,严重威胁着人类身体健康。实验室血清学ELISA诊断技术对于早期诊断乙脑病例,降低死亡率或致残率具有重要价值。本文对我国常用于检测乙型脑炎病例的血清学ELISA技术进行了综述。     

青蒿素类抗疟药的作用机制及耐药机制研究进展

青蒿素作为重要的抗疟药物,因其抗疟作用效率高、速度快、毒性低并且与大部分其他类别的抗疟药无交叉抗性等优点,成为目前全球抗疟的主要药物,虽然在泰柬边境地区已出现了青蒿素耐药性,但就目前全球各．地使用青蒿素及其衍生物为基础的联合疗法（ACT）疗效来看仍能达到90％以上,因此必须对刚刚出现的青蒿素耐药性现象迅速采取遏制行动。本文主要通过描述青蒿素的抗疟机制,讨论其耐药性机制,以及对青蒿素的发展前景作一综述。     

云南省17县(市)褐家鼠体表寄生吸虱调查

目的了解云南省褐家鼠（Rattus norvegicus）体表吸虱寄生状况、种类组成、优势虱种、吸虱群落结构及其空间分布、年龄结构和性比特征。方法选择云南省17县（市）作为调查点，用鼠茏加食饵诱捕褐家鼠，用“全捕法”采集其体表全部吸虱。吸虱群落结构用丰富度（S）、Shannon—Wiener多样性指数（H）、均匀度（J）及优势指数（C）描述。吸虱空间分布格局用分布型指数中的扩散系数（C）、Cassie指数（CA）、丛生指数（I）及聚块指数（m^＊／m）测定。结果在捕获的872只褐家鼠体表共计采集到4种吸虱（7998只），物种丰富度及生物多样性都很低。棘多板虱在整个吸虱群落中占绝对优势，相对优势度Dr为89．12％。吸虱在褐家鼠体表的分布表现为聚集型分布格局，其生活史时期均以雌雄成虫为主，雌雄合计占64．18％，雌雄性比为1．85。结论褐家鼠体表吸虱种类比较单一，群落结构简单，吸虱在宿主体表的寄生呈高度聚集性，雌性高于雄性。褐家鼠体表吸虱种类单一、群落结构简单、优势种明显。显示褐家鼠及其体表寄生吸虱之间的协同进化程度较高。     

Translocation of Campylobacter jejuni across human polarized epithelial cell monolayer cultures.

The ability of Campylobacter jejuni isolates to translocate across an epithelial cell barrier was investigated by using polarized Caco-2 cell monolayers grown on microporous membrane filters. The 4 C. jejuni isolates tested all traversed the Caco-2 cell monolayers and displayed similar translocation kinetics. The number of bacteria crossing the polarized cell monolayers continued to increase with time until 4 h after inoculation, at which time a maximum rate of translocation was observed. Transmission electron microscopy revealed that C. jejuni translocated across polarized Caco-2 cell monolayers by passing both through and between cells. Chloramphenicol, an inhibitor of bacterial protein synthesis, reduced the translocation of C. jejuni. Bacterial attachment, internalization, and translocation were inhibited at low temperature. These data indicate that adherence, penetration, and translocation of C. jejuni require active bacterial and target cell processes and further suggest a role for cellular translocation in the pathogenesis of C. jejuni-mediated enteritis.