DNA条形码技术用于进口货物中肩突硬蜱的鉴定

目的利用DNA条形码技术对入境货物中截获未知种类的蜱进行种属鉴定。方法抽取蜱DNA,用特异性扩增线粒体细胞色素C氧化酶第Ⅰ亚基(COⅠ)基因片段,并测序。利用NCBI进行BLAST比对。结果蜱样本COⅠ基因序列与肩突硬蜱(Ixodes scapularisSay,1821)COⅠ基因匹配度达100%。形态学上,该蜱符合肩突硬蜱的形态学特征。该蜱种在我国尚无检出报道。结论该蜱为肩突硬蜱。这是国内首次报道从进口货物中截获肩突硬蜱。     

DNA条形码技术在鉴定绥芬河口岸日本血蜱和嗜群血蜱中的应用

目的建立用DNA条码技术对绥芬河口岸两种形态学特征非常相近的嗜群血蜱和日本血蜱的鉴定方法,探讨DNA条形码在蜱类鉴定中的实用性。方法在黑龙江绥芬河口岸采集游离血蜱103只,形态学鉴定完毕后,提取蜱样本基因组DNA,采用PCR方法从2种血蜱基因组中扩增线粒体细胞色素氧化酶亚基Ⅰ(COⅠ)基因,测序后进行同源性分析,用Mega6.0软件构建系统发生树并进行系统进化分析。结果经形态学鉴定嗜群血蜱89只,日本血蜱14只;2种血蜱COⅠ基因之间的同源性为87.5%,嗜群血蜱与GenBank中编号KR108867.1公布的嗜群血蜱CO Ⅰ序列相似性为99.8%;日本血蜱与GenBank中编号KR108879.1公布的日本血蜱CO Ⅰ序列相似性为99.8%,与形态学鉴定结果一致。结论对于形态学特征相近蜱种的鉴定,在传统形态学分类的基础上结合DNA条码技术鉴定方法能更准确地鉴定蜱的种类,也能更好地了解其进化关系,为蜱传播疾病的预防控制提供依据。     

基于DNA条形码鉴定口岸截获鼠类

目的 利用基于线粒体细胞色素C氧化酶Ⅰ(COⅠ)基因、线粒体控制区（D-loop）基因、16S rRNA基因的DNA条形码技术对广州口岸截获的1只死鼠进行种类鉴定。方法 从鼠肌肉中提取DNA,用PCR法扩增COⅠ、D-loop、16S rRNA基因片段,将测序结果与GenBank和BOLD systems v4中鼠类的DNA条形码进行比对,用Mega 6.0构建系统发育树,计算遗传距离。结果 该鼠类样本能扩增出COⅠ、D-loop、16S rRNA基因片段,通过COⅠ、16S rRNA基因扩增片段序列比对与德氏柔毛鼠Praomys daltoni同源性均为99%,D-loop基因扩增片段序列比对与猪吻柔毛鼠Praomys rostratus同源性为100%,结合形态学特征,最终鉴定为德氏柔毛鼠Praomys daltoni。结论 COⅠ、16S rRNA基因片段能够对鼠类进行有效鉴定,弥补了形态学鉴定的不足之处。     

新疆边境地区伊宁县图兰扇头蜱形态学及分子生物学鉴定

目的 对新疆边境地区伊宁县图兰扇头蜱进行形态学和分子生物学鉴定.方法 在新疆边境地区的伊宁县随机采集畜牧体表寄生蜱324只,进行形态学初步筛选,从中选取6只形态差异较大的图兰扇头蜱,进行线粒体16S rRNA和线粒体细胞色素C氧化酶亚基Ⅰ (CO Ⅰ)基因序列扩增、测序,并与GenBank登录的图兰扇头蜱参考序列进行遗传进化分析.结果 形态学鉴定采集的伊宁县蜱类皆为图兰扇头蜱,两段序列的碱基组成均显示较高的A+T比例(16SrRNA基因为73.8％,CO Ⅰ基因为70.34％),在变异程度上16S rRNA基因较CO Ⅰ基因明显保守.结论 首次应用形态学、16S rRNA和CO Ⅰ基因测序分析表明新疆伊宁县采集蜱皆为图兰扇头蜱,并证明图兰扇头蜱具有生物多样性.     

上海口岸1只进境犬携带蜱的种类鉴定与溯源分析

目的对上海口岸截获的德国成犬体表蜱进行种类鉴定及溯源分析。方法 2016年11月28日在上海口岸进口的69只德国警犬中的第33号警犬右前肢内侧检获蜱1只,对其进行形态学鉴定,并提取其DNA,扩增线粒体16S r RNA基因进行测序、比对,并对感染途径进行溯源分析。结果形态学鉴定该蜱符合血蜱属的形态特征,分子鉴定表明该蜱的线粒体基因序列与广泛分布于古北区和东洋区的褐黄血蜱(Haemaphysalis flava Neumann,1897)线粒体基因匹配度达98%。结论截获蜱为褐黄血蜱,为犬入境后感染。     

河南口岸截获未知蝇种细胞色素C氧化酶亚基Ⅰ基因分析

目的应用DNA条形码技术对河南口岸截获的1只形态不完整的未知蝇类进行鉴定。方法利用以细胞色素C氧化酶亚基Ⅰ(COⅠ)为目的基因的DNA条形码技术,对该未知蝇类基因组DNA进行扩增、序列比对和分析。结果通过DNA条形码鉴定和序列比对,该未知蝇类的DNA条形码序列与BOLD中绯颜裸金蝇的序列同源性高达100%,确认该蝇种为绯颜裸金蝇。结论 DNA条形码技术弥补了传统形态学鉴定的局限性,在国境口岸医学媒介生物鉴定中有广阔的应用前景。     

褐黄血蜱与铃头血蜱的分子生物学鉴定

目的建立2种形态学特征非常相近的褐黄血蜱及铃头血蜱的分子生物学鉴定方法,探讨它们的系统发生关系。方法在湖北省从动物体表采集寄生蜱,形态学鉴定完毕后,采用PCR方法从2种血蜱基因组中扩增12SrDNA、16SrDNA及线粒体细胞色素氧化酶亚基Ⅰ(COⅠ)基因,测序后进行同源性分析,用PAUP4.0软件分别构建系统发生树并进行系统进化分析。结果 2种血蜱12SrDNA、16SrDNA及COⅠ基因之间的同源性分别为90.8%、90.4%和86.8%,湖北省采集的褐黄血蜱3个基因片段与已知褐黄血蜱的同源性分别为100%、99.5%和99.7%。用这2种蜱的12SrDNA、16SrDNA及COⅠ基因的核苷酸序列分别构建系统发生树,湖北省采集的褐黄血蜱与已知的褐黄血蜱聚在一起,褐黄血蜱及铃头血蜱均形成独立的分支,但用3个基因构建的系统发生树中血蜱属不同种间的亲缘关系不同。结论对于形态学特征相近蜱种的鉴定,在传统形态学分类的基础上结合分子生物学鉴定方法能更准确地鉴定蜱的种类,也能更好地了解其进化关系,为蜱传播疾病的预防控制提供依据。     

国境口岸首次截获贪食睡鼠的分子鉴定及核酸序列分析

目的利用分子鉴定技术,对辽宁大窑湾口岸截获的1只鼠样本(从来自塞尔维亚的原木的集装箱中采集)进行种类鉴定。方法提取已风干鼠样本的基因组DNA,采用动物线粒体细胞色素氧化酶Ⅰ(COⅠ)的通用引物(COⅠ-1和COⅠ-2),进行靶DNA扩增并进行核酸序列分析。结果截获鼠样本的DNA条形码序列与Gen Bank中贪食睡鼠(Glis glis)的序列相似性最高为100%,鉴定为贪食睡鼠。为国境口岸首次截获该鼠种。结论加强出入境交通工具及集装箱鼠类监测工作,保障国境口岸的卫生安全。     

DNA条形码技术在兰州中川机场鼠类鉴定中的应用

目的调查兰州中川机场及其附近地区鼠类的组成,并利用DNA条形码技术对鼠种进行鉴定。方法 2015年1月—2017年7月,在中川机场及其附近地区采用笼夜法采集鼠类,提取鼠肾DNA,用PCR方法扩增线粒体细胞色素c氧化酶亚基Ⅰ(COⅠ)基因并测序,测序结果在DNA条形码专用数据库BOLD中进行比对,确定鼠种。利用Mega 6.0构建分子进化树。对于形态学和COⅠ基因鉴定结果不一致的样本,进一步通过细胞色素b(Cytb)基因进行分子鉴定。结果 118份样品均能扩增出特异性COⅠ基因片段,115份样本的分子鉴定结果与形态学结果基本一致,3份样本形态学鉴定结果与分子鉴定有差异,经Cytb基因序列比对及形态学反复鉴定,确定初步形态学鉴定结果有误,采用分子鉴定结果。结论 DNA条形码技术可以对鼠类进行有效鉴定,是对形态学鉴定的有力补充,为口岸病媒生物的快速识别和鉴定提供了科学依据。     

基于COⅠ基因的媒介蝇类快速分子鉴定研究

目的 为解决蝇类形态学鉴定的不足,建立基于细胞色素C氧化酶亚基Ⅰ（COⅠ）基因的DNA条形码技术对蝇类进行分子鉴定。方法 选取烟台口岸常见的16只蝇类作为研究对象,形态学鉴定后,取蝇的单后足代表微量组织,提取总DNA。依据资料,选取COⅠ国际通用引物LCO1490：5′-GGT CAA CAA ATC ATA AAG ATA TTG G-3′,HCO2198：5′-TAA ACT TCA GGG TGA CCA AAA AAT CA-3′,建立PCR体系,完善PCR程序,有效扩增蝇类的COⅠ基因。纯化PCR产物后进行序列测定和比对。此外,应用Mega5.05软件分别用最大似然法、邻接法、最大简约法分析系统发育,构建系统发育树比较进化关系。结果 16只蝇类COⅠ基因扩增片段长度为690 bp,其中A＋T平均含量高达68.53%。序列比对结果及系统进化关系显示,16只蝇类COⅠ基因的分子鉴定与形态学鉴定结果一致。结论 应用DNA条形码技术可成功扩增蝇类的COⅠ基因,其分子鉴定与形态学鉴定结果完全一致,尤其适用于微量组织样本的鉴定。     

Molecular characterization of a novel Rickettsia species from Ixodes scapularis in Texas.

A novel Rickettsia species of undetermined pathogenicity was detected in Ixodes scapularis. DNA sequencing showed the highest nucleotide sequence similarities with R. australis for the 17 kDa gene, R. helvetica for gltA, and R. montana for rompA. The new organism, provisionally designated as genotype Cooleyi, is highly divergent in three conserved genes from recognized Rickettsia species.     

Identification of protective antigens for the control of Ixodes scapularis infestations using cDNA expression library immunization

Identification of antigens that induce an immune response against tick infestations is required for the development of vaccines against these economically important ectoparasites. In order to identify protective antigens, we constructed a cDNA expression library from a continuous Ixodes scapularis cell line (IDE8) that was initially derived from tick embryos. cDNA clones were subjected to several rounds of screening in which mice were immunized with individual pools and then challenge-exposed by allowing I. scapularis larvae to feed on the immunized and control mice. Immunity against tick infestation was determined by the reduction in the ability of the larvae to feed to repletion and molt to the nymphal stage. Individual clones in pools that induced immunity to larval infestations were partially sequenced and grouped according to their putative protein function by comparison with sequence databases. The screening identified several individual antigens that induced a protective immune response against I. scapularis infestations. Our studies demonstrated for the first time that cDNA expression library immunization (ELI) combined with sequence analysis is a powerful and efficient tool for identification of candidate antigens for use in vaccines against ticks.     

A ten-year study of tick biting in Mississippi: implications for human disease transmission

To determine exactly which tick species bit people in Mississippi, information was gathered on ticks involved in human biting cases for the ten-year period, January 1, 1990-December 31, 1999. Specimens were identified by the author and, in most cases, confirmed by personnel at the Institute of Arthropodology and Parasitology, Georgia Southern University. A total of 119 ticks were recovered from 73 humans during the study period. Seven tick species were represented; most common included the lone star tick, Amblyomma americanum, the gulf coast tick, A. maculatum, the American dog tick, Dermacentor variabilis, and the black-legged deer tick, Ixodes scapularis. Interestingly, no immature Ixodes scapularis were collected. there were several unusual records. Twelve larvae of Amblyomma tuberculatum, a species associated with the gopher tortoise, were removed from a patient. Two Dermacentor albipictus larvae were collected from an elderly woman with no travel history except her backyard. One Dermacentor sp. nymph, removed from a man in central MS, was not even a North American species. One adult female Dermacentor variabilis was involved in a clinical case of tick paralysis. These findings indicate that, although we know which tick species are common human biters, unusual/unreported tick-human interactions may be more common than we think.     

Genetic and morphological characterization of Ixodes apronophorus from Western Siberia,Russia

Genetic variability of I. apronophorus from Western Siberia, Russia was examined using the nuclear internal transcribed spacer 2 (ITS2) and mitochondrial 16S rRNA and cytochrome c oxidase subunit 1 (cox1) genes and compared to those of Ixodes persulcatus and Ixodes trianguliceps from the same site. The I. apronophorus sequences demonstrated the highest nucleotide and haplotype diversity for both mitochondrial genes, whereas I. persulcatus was more variable in the nuclear ITS2. Phylogenetic analysis of the molecular sequence data showed that I. apronophorus differed from other Ixodes species, including Romanian I. apronophorus. The level of identity between 16S rRNA gene sequences of Siberian and Romanian I. apronophorus was only 91%; these sequences did not form a monophyletic group, indicating that I. apronophorus from Siberia and Romania could be different tick species. The analysis of morphological features of the Siberian I. apronophorus confirmed their consistency with those for the previously described I. apronophorus species. Based on the 16S rRNA and ITS2 sequences, Siberian I. apronophorus clustered together with Ixodes kazakstani and Ixodes scapularis, which are the recognized members of the Ixodes ricinus-I. persulcatus species complex within the subgenus Ixodes, and can be assigned to this complex.     

A seven-legged tick: Report of a morphological anomaly in Ixodes scapularis (Acari: Ixodidae) biting a human host from the Northeastern United States

Cases of morphological anomalies in the blacklegged tick, Ixodes scapularis (Acari: Ixodidae), have recently been reported from the Northeastern and upper Midwestern United States, potentially complicating identification of this important vector of human disease-causing pathogens. We hereby report a case of a morphological anomaly in I. scapularis, biting a human host residing in Norwich, Connecticut. Using a dichotomous morphological key, high-resolution and scanning electron microscopy images, as well as DNA sequencing, the tick was identified as an adult female I. scapularis with three legs on the left side of the abdomen versus four on the right side, which we believe is the first case of ectromely in an adult I. scapularis. Using diagnostic genes in polymerase chain reaction, the specimen tested positive for Borrelia burgdorferi sensu lato and Anaplasma phagocytophilum, the causative agents for Lyme disease and anaplasmosis, respectively, and also showed evidence of a rickettsial endosymbiont. Here we discuss recent reports of morphological anomalies in I. scapularis, and emphasize the significance of additional studies of teratology in this important tick species and its potential implications.     

A new species of tick,Ixodes (Ixodes) mojavensis (Acari: Ixodidae), from the Amargosa Valley of California

Ixodes (Ixodes) mojavensis, n. sp. (Acari: Ixodidae), is described from all parasitic stages collected from the endangered vole Microtus californicus scirpensis Bailey, 1900 (Rodentia: Cricetidae), Mus musculus L. 1758 (Rodentia: Muridae), and Reithrodontomys megalotis (Baird; 1857) (Rodentia: Cricetidae) in the Amargosa Valley of California. When first collected in 2014, this tick was tentatively identified as Ixodes minor Neumann, 1902 because the nucleotide similarity between its 16S rDNA sequence and a homologous GenBank sequence from an I. minor from the eastern U.S. was 99.51%. Nevertheless, adults of I. mojavensis differ morphologically from I. minor by hypostomal dentition, absence of a spur on palpal segment I, and punctation patterns; nymphs by the shapes of basis capituli, auriculae, cervical grooves and external files of hypostomal denticles; and larvae by the length of idiosomal setae and hypostomal dentition. DNA sequencing of fragments of 4 different genes, 12S rDNA, 16S rDNA, cytochrome c oxidase subunit I (COI), and intergenic transcribed spacer 2 (ITS2) of I. mojavensis and of closely related species of Ixodes shows that the mitochondrial gene sequences of the new tick species are almost identical to the I. minor homologous genes. Phylogenetically, the two species do not cluster in mutually exclusive monophyletic clades. However, ITS2 sequences of I. mojavensis and I. minor diverge deeply (≥ 5.74% maximum likelihood divergence) and are as different as homologous genes from other recognized species. The discrepancy between the two sets of genes is suggestive of past mitochondrial introgression or incomplete mitochondrial lineage sorting.     

Ticks in the metropolitan area of Berlin,Germany

A high-resolution city map showing the geographic distribution of 12 tick species (Acari: Argasidae, Ixodidae) that have been recorded from the metropolitan area of Berlin, Germany is presented. A total of 237 tick locations was mapped. These include ten ixodid tick species: Dermacentor reticulatus, Haemaphysalis concinna, Hyalomma rufipes, Ixodes ricinus, Ixodes canisuga, Ixodes hexagonus, Ixodes arboricola, Ixodes frontalis, Ixodes trianguliceps and Rhipicephalus sanguineus sensu lato. The two tick species Hy. rufipes and R. sanguineus s.l. are not endemic to Berlin. Hyalomma rufipes ticks are introduced in Europe with migratory birds from Africa every spring. Rhipicephalus sanguineus s.l. are introduced to Central Europe with dogs that had travelled to or were imported from countries where this tick is endemic. In Germany, they are able to develop and reproduce inside heated buildings. Occurrences of two soft tick species, the pigeon tick Argas reflexus and the short-legged bat tick Carios vespertilionis were also mapped. Other tick species that are likely to be endemic to Berlin and its environs, but for which documented findings or geographical coordinates are lacking, are mentioned. These include the long-legged bat tick I. vespertilionis and the marten tick I. rugicollis documented in Brandenburg, the federal state surrounding Berlin. It can be assumed that if appropriate field studies are carried out, these tick species will also be found in the metropolitan area of Berlin. The high-resolution mapping of all tick species found in a city (like Berlin) forms the basis for further investigations into the impact of climate change and changing land use on ticks and tick-borne diseases, precisely in those habitats where most people will live in the future.     

Antibody levels to recombinant tick calreticulin increase in humans after exposure to Ixodes scapularis (Say) and are correlated with tick engorgement indices

The antibody responses of subjects who presented with a definite Ixodes scapularis (Say) tick bite were measured to determine the utility of the antibody response against recombinant tick calreticulin (rTC) as a biologic marker of tick exposure. Subjects bitten by I. scapularis evidenced an increase in anti-rTC antibody levels between visit 1 and visit 2 from 24.3 to 27.1 ng/microl serum (n = 88, p = 0.003), and levels remained elevated at visit 3 (p = 0.005). These anti-rTC antibody levels during visits 2 and 3 were significantly higher than those in four non-exposed controls. Tick engorgement indices, measured on the biting ticks, were found to be correlated with anti-rTC antibody levels (e.g., for visit 3: Pearson's r = 0.357, p = 0.001). Tick engorgement index (TEI), ratio of body length to scutal width, was identified to be the only independent predictor of anti-rTC antibody levels in linear regression models. Logistic regression revealed that a bite from an I. scapularis tick that became engorged (TEI >3.4) was a risk factor for anti-rTC antibody seropositivity (adjusted odds ratio for age and bite location = 7.4 (95% confidence interval 2.1-26.4)). The anti-rTC antibody test had a sensitivity of 0.50 and a specificity of 0.86 for a bite from I. scapularis that became engorged. Immunoblotting revealed that subjects made a specific anti-rTC antibody response.     

Humans infected with relapsing fever spirochete Borrelia miyamotoi, Russia

Borrelia miyamotoi is distantly related to B. burgdorferi and transmitted by the same hard-body tick species. We report 46 cases of B. miyamotoi infection in humans and compare the frequency and clinical manifestations of this infection with those caused by B. garinii and B. burgdorferi infection. All 46 patients lived in Russia and had influenza-like illness with fever as high as 39.5°C; relapsing febrile illness occurred in 5 (11%) and erythema migrans in 4 (9%). In Russia, the rate of B. miyamotoi infection in Ixodes persulcatus ticks was 1%-16%, similar to rates in I. ricinus ticks in western Europe and I. scapularis ticks in the United States. B. miyamotoi infection may cause relapsing fever and Lyme disease-like symptoms throughout the Holarctic region of the world because of the widespread prevalence of this pathogen in its ixodid tick vectors.     

Oral vaccination with vaccinia virus expressing the tick antigen subolesin inhibits tick feeding and transmission of Borrelia burgdorferi

Immunization with the Ixodes scapularis protein, subolesin, has previously been shown to protect hosts against tick infestation and to decrease acquisition of Anaplsma marginale and Babesia bigemina. Here we report the efficacy of subolesin, a conserved tick protein that can act as a regulator of gene expression, expressed from vaccinia virus for use as an orally delivered reservoir - targeted vaccine for prevention of tick infestation and acquisition/transmission of Borrelia burgdorferi to its tick and mouse hosts. We cloned subolesin into vaccinia virus and showed that it is expressed from mammalian cells infected with the recombinant virus in vitro. We then vaccinated mice by oral gavage. A single dose of the vaccine was sufficient for mice to generate antibody response to subolesin. Vaccination with the subolesin expressing vaccinia virus inhibited tick infestation by 52% compared to control vaccination with vaccinia virus and reduced uptake of B. burgdorferi among the surviving ticks that fed to repletion by 34%. There was a reduction in transmission of B. burgdorferi to uninfected vaccinated mice of 40% compared to controls. These results suggest that subolesin has potential as a component of a reservoir targeted vaccine to decrease B. burgdorferi, Babesia and Anaplasma species infections in their natural hosts.