Emerging Chlamydial Infections

Chlamydiae are important intracellular bacterial pathogens of vertebrates. In the last years, novel members of this group have been discovered: Parachlamydia acanthamoebae and Simkania negevensis seems to be emerging respiratory human pathogens, while Waddlia chondrophila might be a new agent of bovine abortion. Various species have been showed to infect also the herpetofauna and fishes, and some novel chlamydiae are endosymbionts of arthropods. In addition, molecular studies evidenced a huge diversity of chlamydiae from both environmental and clinical samples, most of such a diversity could be formed by novel lineages of chlamydiae. Experimental studies showed that free-living amoebae may support multiplication of various chlamydiae, then could play an important role as reservoir/vector of chlamydial infections. Here we reviewed literature data concerning chlamydial infections, with a particular emphasis on the novely described chlamydial organisms.     

棘阿米巴土壤分离株CB/S1的线粒体DNA限制性片段长度多态性

[目的]观察棘阿米巴土壤分离株CB/S1的线粒体DNA限制性片段长度多态性(RFLP)。[方法]从棘阿米巴CB/S1提取线粒体DNA用EcoRI酶切,与土壤分离株CJY/S4比较观察限制性片段长度多态性。用地衣红-卡红染色观察棘阿米巴内共生细菌。[结果]棘阿米巴土壤分离株CB/S1线粒体DNARFLP与CJY/S4相比除了额外的片段(extra bands),两个分离株具有相同的片段模式。经地衣红染色观察CB/S1内共生细菌呈黑色、棒状、不规则的分布在胞质内。[结论]额外的片段表明棘阿米巴CB/S1内含有内共生细菌的环状DNA,并且除了内共生细菌的存在棘阿米巴CB/S1与土壤分离株CJY/S4具有密切的亲缘关系。线粒体DNA限制性片段长度多态性是棘阿米巴分类及发现内共生细菌的简便而有效的方法。     

Molecular identification of Wolbachia from the filarial nematode Mansonella perstans

Wolbachiae are bacterial endosymbionts of insects and many filarial nematodes whose products trigger inflammation in filarial infections. The dependence of the parasites on their endosymbionts has also led to the use of antibiotics directed against the Wolbachiae, therapy that has been demonstrated to have a profound salutary effect on filarial infections. The identification of Wolbachiae in Mansonella species has been conclusively shown for Mansonella ozzardi (Mo), but not for Mansonella perstans (Mp). Using primers known to amplify the 16S ribosomal DNA of other filarial Wolbachiae, an identical 1393bp band was found in all samples tested. Sequence analysis of these samples demonstrated a single consensus sequence for Mp Wolbachia 16S rDNA that was most similar to Wolbachia sequences from other filarial nematodes. When aligned with the only other Mansonella Wolbachia sequence (Mo) there were only 8 nucleotide differences in the 1369bp overlapping sequence. Phylogenetic dendrograms, examining the relationship of the Mp Wolbachia to other Wolbachia 16S rDNA, showed that the Wolbachia tracked almost identically to the 5S rRNA of their parasite host. Wolbachia surface protein (WSP) was also demonstrated in protein extracted from Mp-containing whole blood. In advance of a treatment trial of Mp, a method for the quantitation of Mp Wolbachia was developed and used to demonstrate not only a relationship between microfilarial numbers and Wolbachia copy numbers, but also to demonstrate the effect of antibiotic on ridding Mp of Wolbachia.     

棘阿米巴CB/S1内共生细菌的超微结构

目的:观察棘阿米巴内共生细菌的超微结构。方法:用地衣红-卡红染色确认棘阿米巴土壤分离株CB/S1内存在共生细菌,在透射电镜下观察其超微结构。结果:透射电镜下可见在棘阿米巴胞质内不规则分布的共生细菌,呈棒状,具有双层膜,膜外附着许多棘阿米巴宿主的核糖体。结论:内共生细菌的存在对宿主阿米巴的结构没有引起特殊的改变。     

Wolbachia endosymbionts and human disease control

Most human filarial nematode parasites and arthropods are hosts for a bacterial endosymbiont, Wolbachia. In filaria, Wolbachia are required for normal development, fertility and survival, whereas in arthropods, they are largely parasitic and can influence development and reproduction, but are generally not required for host survival. Due to their obligate nature in filarial parasites, Wolbachia have been a target for drug discovery initiatives using several approaches including diversity and focused library screening and genomic sequence analysis. In vitro and in vivo anti-Wolbachia antibiotic treatments have been shown to have adulticidal activity, a long sought goal of filarial parasite drug discovery. In mosquitoes, it has been shown that the presence of Wolbachia can inhibit the transmission of certain viruses, such as Dengue, Chikungunya, Yellow Fever, West Nile, as well as the infectivity of the malaria-causing protozoan, Plasmodium and filarial nematodes. Furthermore, Wolbachia can cause a form of conditional sterility that can be used to suppress populations of mosquitoes and additional medically important insects. Thus Wolbachia, a pandemic endosymbiont offers great potential for elimination of a wide-variety of devastating human diseases.     

霍乱弧菌O139感染棘阿米巴的实验研究

目的探讨霍乱弧菌能否在阿米巴原虫内生存。方法采用霍乱弧菌O139与多噬棘阿米巴的共培养方法，通过倒置显微镜、革兰染色和电镜超薄切片观察霍乱弧菌在阿米巴滋养体和包囊内生存情况。结果培养24h，革兰染色可见霍乱弧菌O139已进人阿米巴滋养体的吞噬泡内，随共培养时间的延长，可见吞噬泡内霍乱弧菌O139增多。电镜下可见霍乱弧菌O139在阿米巴环境中的不同感染期：包括胞饮期、吞噬泡形成期、增殖期及滋养体裂解释放，部分感染的滋养体发生包囊化，胞浆吞噬泡内可见存活O139弧菌。结论霍乱弧菌O139能在棘阿米巴滋养体内生存繁殖，并存活于包囊胞浆的吞噬泡中，因此棘阿米巴原虫可能是霍乱弧菌O139的环境贮存宿主之一。     

棘阿米巴土壤分离株CB/S1内共生细菌的16S rDNA序列分析

用地衣红-卡红染色进行共生菌的形态观察,鉴定棘阿米巴CB/S1内共生细菌。克隆内共生细菌的16S rDNA基因,进行基因序列分析。结果表明,经地衣红-卡红染色棘阿米巴CB/S1内共生细菌呈黑色和棒状,在胞质内不规则分布。棘阿米巴CB/S1内共生细菌的16S rDNA基因长1534bp,与类亚洲嗜阿米巴杆菌(Candidatus Amoebophilus asiaticus 5a2)和韩国棘阿米巴分离株KA/E21内共生细菌的16S rDNA基因的同源性均为98%。进化树分析表明,棘阿米巴CB/S1内共生细菌与韩国棘阿米巴KA/E21内共生细菌、类亚洲嗜阿米巴杆菌、黑脚硬蜱内共生细菌和伯恩蚜小蜂内共生细菌等细菌构成单系。     

Biological factors influencing tissue compartmentalization of trace metals in the deep-sea hydrothermal vent bivalve Bathymodiolus azoricus at geochemically distinct vent sites of the Mid-Atlantic Ridge

In this study, we investigated on concentrations of trace metals (Al, Cd, Mn, Co, and Hg) in the hydrothermal bivalve Bathymodiolus azoricus, a dominant species at most vent sites along the Mid-Atlantic Ridge (MAR), and in its endosymbiont bacteria and commensal parasite Branchipolynoe seepensis. Comparison of our results with data from the literature on non-hydrothermal bivalves suggests lack of "extreme" uptake of trace metals by B. azoricus, except for Hg concentration which exceeded manyfold previously reported values. Mussels collected from three geochemically distinct vent sites, Menez Gwen, Lucky Strike, and Rainbow, along the MAR showed significant differences in tissue concentration of metals. Proportionality of metals in soft tissues of mussels reflected variation of water chemistry at different vents, which in turn conserved the order of trace metal prevalence in undiluted fluids. There were significant tissue-specific differences in trace metal compartmentalization for all metals investigated. Byssus thread contained the highest metal concentration among examined tissues, and thus it is suggested to be an important detoxification route. Size-dependent differences in metal concentrations were detected only for Hg, revealing a general trend of small mussels accumulating more metal than big mussels. Endosymbiont bacteria are shown to exclusively sequester Al from the host gill and contribute to removal of other toxic metals in mussels from Menez Gwen. The commensal parasite present in all mussels from Lucky Strike had higher tissue concentrations of Mn, Al, and Co than the host gill, unlike Cd and Hg which were considerably lower in the former, and thus its role in detoxification remains unclear. Bioaccumulation potential of vent bivalves and associated organisms are quantified as concentration factors and compared to make inferences on the putative role of the endosymbiont bacteria and the commensal parasite in detoxification of trace metals.     

A mitochondrial intron sequence in the 5′-flanking region of a plant nuclear lectin gene

Summary A sequence fragment from the cis-splicing intron between exons a and b of the NADH-dehydrogenase subunit 5 gene (nad5) in plant mitochondria is also present in one of two closely related nuclear-encoded lectin genes of Dolichos biflorus. This sequence of 116 nucleotides is the major difference in the 5-flanking region of two recently described lectin genes (Harada et al. 1990). The stem and leaf lectin DB58 does not contain the insert, while the otherwise more than 90% identical 5-flanking region of the seed lectin is interrupted by this mitochondrial intron sequence.