人粒细胞埃立克体病——又一种蜱传病

人粒细胞埃立克体病是由人粒细胞埃立克体(HumanGranulocyticEhrlichia,HGE)引起的一种经蜱传播的自然疫源性疾病。该病是继莱姆病、斑点热及人单核细胞埃立克体病等病之后,于1994年发现的又一种蜱传疾病。研究结果表明,HGE是一种以粒细胞为主要靶细胞的埃立克体。通过测?..     

用16S rRNA基因序列分析从西藏的微小牛蜱中检出的埃立克体

用埃立克体属特异性套式PCR和DNA序列测定从西藏微小牛蜱检出边缘无形体和埃立克体;用半套式PCR扩得该埃立克体的16S rRNA基因,并测定了它的序列;将该埃立克体的16S rRNA基因序列与其它埃立克体的16S rRNA基因序列进行对比分析,结果证明它的16S rRNA基因与埃立克体属的犬埃立克体群16S rRNA基因相似水平最高(97%～98%);用16S rRNA基因序列做系统发育分析,结果显示该采自西藏的微小牛蜱的埃立克体可能是与查菲埃立克体密切相关的一种新埃立克体.     

野外采集标本中人埃立克体16S rRNA基因扩增方法及应用

本文应用特异引物,通过多对半巢式PCR从采自内蒙古大兴安岭的蜱标本中扩增出人粒细胞埃立克体和查菲埃立克体的16SrRNA全基因,一方面提供了这2种埃立克体存在于中国的证据,另一方面为今后进行埃立克体病的病原、媒介和宿主的调查研究提供了一个可行的方法.并从一只大林姬鼠的脏器中检测到EC16SrRNA基因片段.     

人类无浆体病的病原学和流行病学研究进展

无浆体病是由无浆体属（Anaplasma）微生物引起的一类反刍动物慢性和急性传染病，其特征为高热、贫血、消瘦、黄疸和胆囊肿大。近年随着立克次体目微生物分类学的变化，原属埃立克体的马埃立克体、嗜吞噬细胞埃立克体和新近发现的引起人粒细胞埃立克体病（HGE）的病原体（HGE-A）三者被重新分类，成为无浆体属中的新种一嗜吞噬细胞无浆体。嗜吞噬细胞无浆体是一种人畜共患病病原体，对人、畜均有较强致病性，因此．人类嗜吞噬细胞无浆体病成为一种新的人类传染病。本文重点总结人类无浆体病的病原学和流行病学方面的一些研究进展。     

PCR检测蜱中查菲埃立克体DNA及其序列分析

应用从查菲埃立克体１６ＳｒＲＮＡ基因序列高变区构建的特异引物，进行ＰＣＲ，检测蜱标本中病原体ＤＮＡ。结果从云南采集的龟形花蜱、从福建采集的越原血蜱和卵形硬蜱扩增出３８９ｂｐ的特异ＤＮＡ片段。收集龟形花蜱和越原血蜱的特异ＰＣＲ产物，通过与Ｔ载体连接，进行克隆和序列测定。其ＤＮＡ序列与美国查菲埃立克体分离株对应位置相差一个核苷酸，与其它种埃立克体的同源性为８０．７％～９６．１％。这是首次在我国发现埃立克体存在的病原线索，表明在我国南方可能存在人单核细胞埃立克体感染的自然疫源地     

中国—尼泊尔边境樟木口岸蜱类携带病原体调查研究

本研究于2012～ 2014年在中国-尼泊尔樟木口岸采集游离蜱和寄生蜱,形态学鉴定后,采用PCR检测蜱标本中伯氏疏螺旋体、埃立克体、立克次体、贝氏柯克斯体、土拉菌和巴通体6种病原体;采用RT-PCR检测森林脑炎、新疆出血热病毒、布尼亚病毒3种病原体.结果在296只蜱中检出伯氏疏螺旋体阳性5个、埃立克体16个、立克次体11个、巴通体16个.本研究初步获得中尼边境樟木口岸蜱媒携带病原情况,为该区域蜱传疾病的防控和研究提供依据.     

黑龙江省部分林区全沟硬蜱复合感染重要蜱媒病原的调查研究

为了研究我国重要蜱媒病的复合感染情况,本文选择黑龙江林区蜱媒疾病高发区域,以莱姆病、森林脑炎、人巴贝西原虫病、埃立克体等蜱媒病原为目标,应用聚合酶链式反应对该地区采集的全沟硬蜱可能感染的蜱媒病原情况进行检测,以探讨这些蜱媒疾病在媒介全沟硬蜱体内的复合感染状况。结果表明,该地区的全沟硬蜱感染有莱姆病、森林脑炎、人巴贝西原虫病、埃立克体、斑点热等5种疾病的病原体,感染阳性率在1.05%~10.5%之间;在这些感染个体中,将近40%的个体属于复合感染,复合感染的类型有双重感染和三重感染。其中,莱姆病螺旋体和其他病原体复合感染的比例很高;没有发现埃立克体和人巴贝西原虫的复合感染现象。我国蜱媒病原的复合感染情况,理应引起预防、临床和公共卫生相关人员的充分关注。     

查菲埃立克体表面抗原P120蛋白基因的克隆与表达

查菲埃立克体 (Ｅｈｒｌｉｃｈｉａｃｈａｆｆｅｅｎｓｉｓ)是人单核细胞埃立克体病 (ｈｕｍａｎｍｏｎｏｎ ｃｙｔｉｃｅｈｒｌｉｃｈｉｏｓｉｓ,ＨＭＥ)的病原体 ,已证实我国存在该病原。血清学分析是目前诊断ＨＭＥ及其流行病学调查的主要方法。但由于该病原体为严格胞内寄生菌 ,难以通过细胞培养制备大量抗原去满足临床ＨＭＥ的血清学诊断和流行病学调查的需要。Ｐ12 0 (相对分子质量为 12 0×10 3蛋白 )为查菲埃立克体主要表面抗原 ,具有种特异性。该蛋白基因包含了多个连续的 2 40ｂｐ重复单位 ,占全基因的 6 0 % ,并均为Ｂ淋巴细胞识…     

贝氏柯克斯体毒力相关基因芯片对其他胞内寄生菌基因组DNA检测结果分析

目的用建立的贝氏柯克斯体毒力相关基因芯片研究贝氏柯克斯体与其致病性相似的专性胞内寄生菌（立克次体、埃立克体、新立克次体）,以及与其密切相关的兼性胞内寄生菌（巴通体和肺炎军团菌）等病原菌的毒力基因的差异。方法贝氏柯克斯体国际标准株-九里株作为本研究参考株,从全基因序列中选取166个毒力及毒力相关基因进行PCR扩增,纯化后的产物制备基因芯片。采用双色荧光标记,待测DNA（即用于分析的各菌株基因组DNA）用Cy5标记,贝氏柯克斯体九里株参照基因组DNA用Cy3标记。芯片杂交后,采用软件GenePixPro4.1,辅助以软件Excel,进行图片处理和数据分析。结果芯片的166个基因片段中有165个存在于所有贝氏柯克斯体属的6个分离株中,另一锚定蛋白（AnkI）基因（CBU1213）仅存在于九里株及Grita株;立克次体属的5株菌株均与CBU1631和CBU1125杂交;埃立克体属的3种菌株与新立克次体属的3种菌株均含有基因CBU1125;东方属的1株菌株具有基因CBU1449,而巴通体属的菌株,军团菌和大肠杆菌与基因芯片均无杂交。结论贝氏柯克斯体种内基因组具有高度保守性,它的专性细胞内寄生菌的毒力相关基因与胞外寄生菌的毒力相关基因有非常显著差异。     

我国北方蜱中人粒细胞埃立克体16S rRNA基因的检测

本文应用人粒细胞埃立克体病 ( HGE)的病原体的 1 6S r RNA基因序列的特异引物对采自我国北方地区的一些蜱标本进行扩增 ,首次从内蒙古大兴安岭采集的全沟硬蜱、森林革蜱和嗜群血蜱 ,以及从新疆精河采集的全沟硬蜱和草原革蜱中扩增出该病原体的 1 6S r RNA基因片段。所测出的 967bp序列与美国 HGE株 ( Gen Bank U0 2 52 1 )的同源性为 1 0 0 %     

Granulocytic Ehrlichiosis in Tick-Immune Guinea Pigs

We investigated whether Ixodes scapularis-mediated host immunity interrupts transmission of the agent of human granulocytic ehrlichiosis (aoHGE) to guinea pigs. Ticks infected with aoHGE readily transmitted aoHGE to tick-immune guinea pigs, despite incomplete tick engorgement and host attachment. Although tick immunity can prevent Lyme borreliosis, protection is not afforded against granulocytic ehrlichiosis.     

Evidence of the human granulocytic ehrlichiosis agent in Ixodes ricinus ticks in Switzerland

A total of 1,667 Ixodes ricinus ticks were collected from five regions in Switzerland where there have been sporadic occurrences of granulocytic ehrlichiosis in dogs and horses. The ticks were examined for rickettsiae of the Ehrlichia phagocytophila group via nested PCR. Twenty-one ticks (1.3%) were positive; 3 (0.5%) were nymphs, 6 (1.3%) were adult males, and 12 (1.9%) were adult females. The number of positive ticks varied with the stage of development and with the geographical origin. Nucleotide sequencing of the isolated PCR products identified these products as part of the 16S rRNA gene of Ehrlichia. In addition, these products had 100% homology with the agent of human granulocytic ehrlichiosis. The occurrence of this agent in I. ricinus in Switzerland presents a potential danger of transmission of granulocytic ehrlichiosis to dogs, horses, and humans.     

Verses, viruses, and the vulnerability of the blood supply in industrialized countries

In the last 30 years, tremendous progress in identifying transfusion-transmitted viruses such as HBV, HCV, and HIV in industrialized countries has been achieved. Currently, the residual risk of transmitting these viruses through transfusion is very low especially after the introduction of "minipool" nucleic acid-amplification tests. Despite these major technical advances, there remains a legitimate concern as to the transmission of other blood-borne infectious agents through blood transfusion. Among these agents are HBV mutants, occult HBV, and HCV infections, malaria, Chagas, West Nile, dengue, and vesiviruses, bacterial infections such as Yersinia enterocolitica, and tick borne diseases such as human monocytic ehrlichiosis, human granulocytic ehrlichiosis, Rocky Mountain spotted fever, and Lyme and prion diseases such as Creutzfeldt and variant Creutzfeldt. Most of these agents are very rarely transmitted by transfusion in industrialized countries. However, an awareness of their possible transmission is essential for the control of spread of these diseases among the public by human-to-human transmission via blood transfusion. This review summarizes the current status of prevalence and diagnosis of these emerging diseases and also updates our knowledge on recently discovered non-pathogenic blood-borne viruses such as GB virus C and Torque Tenoviruses.     

Equine granulocytic ehrlichiosis in Connecticut caused by an agent resembling the human granulocytotropic ehrlichia.

The first recognized cases of equine granulocytic ehrlichiosis in New England are described. The DNA sequence of the 16S rRNA gene of the causative ehrlichia was found to be identical to that of the human granulocytotropic ehrlichia, the agent of human granulocytic ehrlichiosis.     

Serological responses to Ehrlichia equi, Ehrlichia chaffeensis, and Borrelia burgdorferi in patients from New York State.

Serological testing at the New York State Department of Health for human granulocytic ehrlichiosis in the residents of Westchester County, N.Y., was performed with specimens from 176 patients by the indirect fluorescent-antibody (IFA) technique with Ehrlichia equi MRK-infected neutrophils. To understand whether human monocytotropic ehrlichiosis also occurs in this northeastern geographic region, specimens were also tested for antibodies to Ehrlichia chaffeensis Arkansas. Screening tests and immunoblots for Lyme disease (Borrelia burgdorferi infection) were also performed. Thirty-two patients had antibodies only to E. equi and 21 patients had antibodies to both E. equi and E. chaffeensis, whereas 12 patients had only E. chaffeensis antibodies by the IFA technique. The remaining patients did not have antibodies to either ehrlichia. Eighteen serum samples from 13 of these patients were coded and sent to the Ehrlichia Research Laboratory (Baltimore, Md.) for repeat analysis by the IFA test and for E. equi and E. chaffeensis immunoblots. Immunoblot analysis for E. equi in samples with positive IFA test results confirmed the results for eight of the nine specimens. Immunoblot analyses for E. chaffeensis were negative for all 18 serum samples. Borrelia-reactive antibodies were found in sera both from patients with granulocytic ehrlichiosis and from patients with monocytotropic ehrlichiosis from New York State. Our results suggest that E. equi antigen is an appropriate substrate for identifying human granulocytic ehrlichiosis. E. chaffeensis antigen lacks appropriate sensitivity to serve as a surrogate substrate for the detection of human granulocytic ehrlichiosis and should be used solely for the diagnosis of human monocytotropic ehrlichiosis. Heat shock proteins may, in some cases, cause cross-reactivity between B. burgdorferi and ehrlichiae.     

First Cases of Acute Human Granulocytic Ehrlichiosis in Poland

The first three cases of acute human granulocytic ehrlichiosis in Poland are described. Blood samples were tested by an indirect immunofluorescence method to detect specific serum antibodies, and the polymerase chain reaction was used to detect ehrlichial DNA. Additionally, peripheral blood smears were examined for the presence of morulae. According to criteria of the Centers for Disease Control and Prevention, all three cases can be classified as confirmed granulocytic ehrlichiosis. Using the criteria recommended by a consensus group, however, two cases can be classified as confirmed granulocytic ehrlichiosis and one case as probable granulocytic ehrlichiosis.     

Acquisition of coinfection and simultaneous transmission of Borrelia burgdorferi and Ehrlichia phagocytophila by Ixodes scapularis ticks

The agents of Lyme disease (Borrelia burgdorferi) and human granulocytic ehrlichiosis (Ehrlichia phagocytophila) are both transmitted by the tick Ixodes scapularis. In nature, ticks are often infected with both agents simultaneously. We studied whether previous infection with either Borrelia or Ehrlichia in ticks would affect acquisition and transmission of a second pathogen. Ehrlichia-infected I. scapularis nymphs were fed upon Borrelia-infected mice, and Borrelia-infected I. scapularis nymphs were fed upon Ehrlichia-infected mice. The efficiency with which previously infected nymphal ticks acquired a second pathogen from infected hosts was compared to that of uninfected ticks. An average of 51% +/- 15% of ticks acquired Ehrlichia from infected mice regardless of their prior infection status with Borrelia. An average of 85% +/- 10% of ticks acquired Borrelia from infected mice regardless of their prior infection status with Ehrlichia. Also, we assessed the efficiency with which individual nymphs could transmit either agent alone, or both agents simultaneously, to individual susceptible hosts. An average of 76% +/- 9% of Borrelia-infected ticks and 84% +/- 10% of Ehrlichia-infected ticks transmitted these agents to mice regardless of the presence of the other pathogen. There was no evidence of interaction between the agents of Lyme disease and human granulocytic ehrlichiosis in I. scapularis ticks. The presence of either agent in the ticks did not affect acquisition of the other agent from an infected host. Transmission of the agents of Lyme disease and human granulocytic ehrlichiosis by individual ticks was equally efficient and independent. Dually infected ticks transmitted each pathogen to susceptible hosts as efficiently as ticks infected with only one pathogen.     

Ehrlichia ewingii, a newly recognized agent of human ehrlichiosis.

BACKGROUND: Human ehrlichiosis is a recently recognized tick-borne infection. Four species infect humans: Ehrlichia chaffeensis, E. sennetsu, E. canis, and the agent of human granulocytic ehrlichiosis. METHODS: We tested peripheral-blood leukocytes from 413 patients with possible ehrlichiosis by broad-range and species-specific polymerase-chain-reaction (PCR) assays for ehrlichia. The species present were identified by species-specific PCR assays and nucleotide sequencing of the gene encoding ehrlichia 16S ribosomal RNA. Western blot analysis was used to study serologic responses. RESULTS: In four patients, ehrlichia DNA was detected in leukocytes by a broad-range PCR assay, but not by assays specific for E. chaffeensis or the agent of human granulocytic ehrlichiosis. The nucleotide sequences of these PCR products matched that of E. ewingii, an agent previously reported as a cause of granulocytic ehrlichiosis in dogs. These four patients, all from Missouri, presented between May and August 1996, 1997, or 1998 with fever, headache, and thrombocytopenia, with or without leukopenia. All had been exposed to ticks, and three were receiving immunosuppressive therapy. Serum samples obtained from three of these patients during convalescence contained antibodies that reacted with E. chaffeensis and E. canis antigens in a pattern different from that of humans with E. chaffeensis infection but similar to that of a dog experimentally infected with E. ewingii. Morulae were identified in neutrophils from two patients. All four patients were successfully treated with doxycycline. CONCLUSIONS: These findings provide evidence of E. ewingii infection in humans. The associated disease may be clinically indistinguishable from infection caused by E. chaffeensis or the agent of human granulocytic ehrlichiosis.     

Coinfection with Borrelia burgdorferi and the agent of human granulocytic ehrlichiosis alters murine immune responses, pathogen burden, and severity of Lyme arthritis

Lyme disease and human granulocytic ehrlichiosis (HGE) are tick-borne illnesses caused by Borrelia burgdorferi and the agent of HGE, respectively. We investigated the influence of dual infection with B. burgdorferi and the HGE agent on the course of murine Lyme arthritis and granulocytic ehrlichiosis. Coinfection resulted in increased levels of both pathogens and more severe Lyme arthritis compared with those in mice infected with B. burgdorferi alone. The increase in bacterial burden during dual infection was associated with enhanced acquisition of both organisms by larval ticks that were allowed to engorge upon infected mice. Coinfection also resulted in diminished interleukin-12 (IL-12), gamma interferon (IFN-gamma), and tumor necrosis factor alpha levels and elevated IL-6 levels in murine sera. During dual infection, IFN-gamma receptor expression on macrophages was also reduced, implying a decrease in phagocyte activation. These results suggest that coinfection of mice with B. burgdorferi and the HGE agent modulates host immune responses, resulting in increased bacterial burden, Lyme arthritis, and pathogen transmission to the vector.