赣州市5例恙虫病调查报告

5例病人均有发热及典型的焦痂体征，焦痂率达80％，恢复期血清抗体阳性，对强力霉素高度敏感。发病时间为6、7月份。男女均有发病，以农民为主，均有野外作业史，呈散在流行。调查首次证明赣州市有恙虫病的存在，流行病学特征明显。     

恙虫病东方体在无生命培养基内生长的研究

目的　恙虫病东方体 (Orientiatsutsugamushi;Ot)被认为属专性细胞内寄生。特别是制备大量抗原培养难的问题 ,是近一个世纪以来人们渴望解决的难题。为证实是否能在无生命培养基生长。方法　用Vero -E6个单层组织细胞培养OtJL - 90株与标准Gilliam株 ,在合适时取该培养物接种于Ⅲ号无生命固体培养基培养 ,置 36℃ (± 1℃ )培养 18- 2 4h。结果　可见生长一群无色透明或半透明光滑、湿润、圆形或枫叶样小菌落 ,并产生一种难闻的臭味。两种方法培养物分别做了生物学性状鉴定、形态染色、小白鼠致病力、血清学特异性间接免疫荧光检测。各株Ot经两种培养获得培养物特性基本一致。结论　Ot能在细胞内生长也能在无生命培养基内生长 ,解决了Ot大量抗原培养难的困扰。     

应用PCR技术检测恙螨体内恙虫病立克次体动态和经卵传递的研究

本文应用聚合酶链反应技术检测恙虫病立克次体实验感染的恙螨体内立克次体的动态变化，通过人工腹腔接种而感染的恙螨成虫，恙虫病立克次体至少能在其体内生存３６０天和经卵传递４代；通过未食幼虫叮咬病小鼠而感染的恙螨，经饱蚴、若蛹、若虫、成蛹和成虫阶段，恙虫病立克次体检测均呈阳性，至少能在成虫期体内生存２７０天和经卵传递１代。     

Survival of two Orientia tsutsugamushi bacterial strains that infect mouse macrophages with varying degrees of virulence

Orientia tsutsugamushi, an intracellular parasitic bacterium, comprises numerous strains of differing virulence. When BALB/c mice were infected intraperitoneally with this pathogen, a virulent strain known as Karp was found to multiply in the intraperitoneal macrophages and kill the mouse. In contrast, an avirulent strain, Kuroki, was shown to invade macrophages but be eliminated from the cells, allowing mouse survival. O. tsutsugamushi invades its host cell cytoplasm through phagocytosis and disruption of phagosomal membranes but some bacteria are then killed by phago-lysosomes within 1h of infection. Microscopic observations could not differentiate the Karp and Kuroki strains during entry and subsequent cell killing by phago-lysosomes. However, the Kuroki cells failed to divide and were markedly deformed following cytoplasmic invasion at several days post-infection. These findings suggest that macrophages have a mechanism to eliminate O. tsutsugamushi in the cytoplasm, if the invading bacteria escape phagosomal clearance, and that it is this mechanism that Kuroki does not survive. Additionally, significant levels of nitric oxide (NO) are produced in macrophages by Kuroki, but not by Karp. An NO synthase inhibitor, however, does not increase the growth of Kuroki, suggesting that NO is induced in a strain-dependent manner but does not effect proliferation.     

恙虫病东方体Sta56抗原的原核表达、纯化及其在间接ELISA中的应用

目的　构建含恙虫病东方体sta5 6基因的重组表达质粒 ,在E .coli中表达Sta5 6重组抗原 ,纯化后用于间接ELISA检测恙虫病。方法　从含有恙虫病东方体Karp株sta5 6基因的重组质粒TOPO sta5 6扩增出截短的sta5 6 ,定向插入pET30a载体 ,转化大肠杆菌BL2 1(DE3) ,IPTG诱导表达 ,用SDS PAGE及Westernblot进行分析 ;采用电洗脱方法纯化重组抗原并应用于间接ELISA检测恙虫病。结果　以截短的sta5 6基因片段构建了重组表达质粒pETOt95 7,重组的Sta5 6抗原可在E .coli中以融合蛋白的形式有效表达 ,SDS PAGE显示了一条相对分子质量 (Mr)为 4 0 .3× 10 3 的蛋白表达带 ,West ernblot证实该融合蛋白能被恙虫病患者阳性血清所识别。电洗脱纯化的重组抗原应用于间接法ELISA检测恙虫病 ,与间接免疫荧光法IFAT比较 ,其敏感性和特异性分别为 91.7%和 76 .5 %。结论　在大肠杆菌中表达的Sta5 6重组抗原具有免疫反应性 ,纯化后可用作免疫诊断试剂。     

mNGS协助诊断无焦痂型丛林斑疹伤寒1例

 丛林斑疹伤寒是由恙虫病东方体感染引起的一种急性人畜共患传染病。临床表现为发热、皮疹、淋巴结肿大,被叮咬部位出现特异性焦痂和溃疡是该病诊断的最主要依据,没有焦痂和溃疡的患者往往很难识别。本文报告1例54岁男性患者,以发热、淋巴结肿大及全身多个脏器损伤为主要临床表现,因无特征性焦痂,且经验性使用抗菌药物效果不佳,给诊疗带来困难。病例标本送宏基因组二代测序(mNGS)明确病原体为恙虫病东方体。换用左氧氟沙星及阿奇霉素治疗后患者症状很快好转,最终痊愈出院。mNGS已被证明比传统培养方法更敏感,在早期诊断恙虫病方面优于传统临床方法,尤其是对于没有典型焦痂的患者。     

恙虫病东方体56kDa抗原基因片段在不同载体的表达

目的 构建恙虫病东方体56kDa表面抗原基因(sta56)片段在不同载体的重组表达质粒，在E．coli中表达sta56重组抗原并比较不同表达系统对sta56的表达效果。方法 从含有恙虫病东方体Karp株sta56基因的重组克隆，扩增出不同长度的截短的sta56片段．定向插入pPROEX HTb及pET30a载体，转化大肠埃希菌DH5a或BL21(DE3)，IPTG诱导表达，应用十二烷基磺酸钠—聚丙烯酰胺凝胶电泳(SDS-PAGE)观察重组蛋白表达情况。应用蛋白印迹(WB)方法分析重组抗原的活性。结果 成功构建含sta56不同长度片段的重组表达质粒pHTbOt957、pHTbOt498、pHTbOt342和pETOt957、pETOt498、pETOt342，各重组子均可在E．coli中以融合蛋白的形式有效表达，SDS-PAGE显示各表达重组子表达不同分子量的重组蛋白，WB证实各重组蛋白均能被恙虫病患者阳性血清所识别。结论 恙虫病东方体Karp株sta56基因可在大肠埃希菌获得高效表达，pET30a对sta56的表达效果优于pPROEX HTb；重组蛋白具有免疫反应性，纯化后可用作免疫诊断抗原。     

Molecular Epidemiology and Genetic Diversity of Orientia tsutsugamushi from Patients with Scrub Typhus in 3 Regions of India

Scrub typhus, an acute febrile illness that is widespread in the Asia-Pacific region, is caused by the bacterium Orientia tsutsugamushi, which displays high levels of antigenic variation. We conducted an investigation to identify the circulating genotypes of O. tsutsugamushi in 3 scrub typhus–endemic geographic regions of India: South India, Northern India, and Northeast India. Eschar samples collected during September 2010–August 2012 from patients with scrub typhus were subjected to 56-kDa type-specific PCR and sequencing to identify their genotypes. Kato-like strains predominated (61.5%), especially in the South and Northeast, followed by Karp-like strains (27.7%) and Gilliam and Ikeda strains (2.3% each). Neimeng-65 genotype strains were also observed in the Northeast. Clarifying the genotypic diversity of O. tsutsugamushi in India enhances knowledge of the regional diversity among circulating strains and provides potential resources for future region-specific diagnostic studies and vaccine development.     

云南省泸西县啮齿动物携带立克次体调查

目的 调查云南省泸西县啮齿动物携带恙虫病东方体、无形体和埃立克体的状况,了解该类病原体在当地自然界中的保存状况和基因特征。方法 用鼠笼和鼠夹在云南省泸西县捕鼠,将捕获的动物种类鉴定后解剖取脾脏,活鼠取血。采用巢式PCR扩增脾脏的恙虫病东方体groEL基因,无形体和埃立克体的16S rRNA基因特异片段;测定PCR扩增阳性产物的DNA序列,对获得序列进行序列比对和系统进化分析。IFA法检测鼠血清中恙虫病东方体IgG抗体。结果 在泸西县共捕获啮齿动物10种225只。其中黄胸鼠36.89%(83/225)、大绒鼠35.11%(79/225)和中华姬鼠13.78%(31/225)为优势鼠种。获得鼠血清85份。鼠脾脏中检测到5株东方体groEL基因阳性标本,带毒鼠种为黄胸鼠2.41%(2/83)和大绒鼠3.80%(3/79)。同源性比较显示,这5株东方体的相似性在99.02%~100%之间,他们分别与GenBank中已知立克次体序列的相似性在98.75%~100%。系统发生树显示,5株OT与来自日本、泰国和中国安徽的菌株位于同一分支。3份16S rRNA阳性标本,其中1份埃立克体阳性,来源于大绒鼠;1份沃尔巴克氏体和1份巴尔通体阳性均来源于黄胸鼠。无形体均为阴性。埃立克体株序列比对显示与来自美国、中国和巴西的埃立克体基因同源性为98.0%~100%,并与分离自美国野外工作者皮肤的伊文氏埃立克体在同一分支。鼠血清恙虫病IgG抗体阳性7份,阳性率8.24%(7/85)。结论 该地区存在以黄胸鼠和大绒鼠为主要宿主的恙虫病自然疫源地。埃立克体、巴尔通体和沃尔巴克氏体在啮齿动物中也存在感染,需注意防控。     

恙螨体内恙虫病立克次体经精胞传递的实验研究

本文报道地里纤恙螨雄虫人工接种恙虫病立克次体后与雌虫配对培养和传代，应用幼虫叮咬小鼠分离立克次体和PCR结合核酸杂交（核酸杂交检测PCR产物）检测子代体内立克次体的结果。幼虫叮咬小鼠分离立克农作检查第3子代幼虫体内立克次体阳性。PCR结合核酸杂交检测佛山市的病人恙虫病立克次休（未定株）接种雄虫和健康雌虫配对的第1、2、3子代成虫体内立克次体DNA阳性。Karp株接种雄虫的第1子代幼虫体内立克次体的幼虫叮咬小鼠法和PCR结合核酸杂交均呈阳性。