长角血蜱和微小扇头蜱的形态与分子生物学鉴定

目的 建立鉴定长角血蜱和微小扇头蜱的形态学和分子生物学相结合的方法.方法 采集自湖北和河南省布尼亚新病毒疫区家养动物体表寄生的蜱及草丛、灌木中的蜱;先以形态学鉴定,后用PCR方法扩增得到蜱的12S rDNA,测序后进行同源性和系统进化分析.结果 形态学方法鉴定采集到两种蜱:长角血蜱(Haemaphysalis longicornis)和微小扇头蜱(Rhipicephalus microplus).蜱的12S rDNA经克隆、测序,用PAUP 4.0软件构建系统发生树,湖北、河南省两种蜱的12S rDNA序列分别与长角血蜱和微小扇头蜱聚类,与形态学鉴定结果一致.结论 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.     

Cloning and characterization of Rhipicephalus appendiculatus voraxinα and its effect as anti-tick vaccine

Male tick-derived voraxinα and voraxinβ, a pair of testicular proteins, are transferred to female via copulation to stimulate female blood feeding in the tick Amblyomma hebraeum (A. hebraeum). Immunized animals with recombinant (r-)voraxinα and voraxinβ have been shown as highly resistant to the tick infestation. In this study, we describe the cloning and characterization of voraxinα homologue from the tick Rhipicephalus appendiculatus (R. appendiculatus), the major vector for East Coast fever in Eastern Africa. The sequence analysis of the R. appendiculatus voraxinα indicated that the deduced amino acid sequence had high similarity with voraxinα of the tick A. hebraeum and Dermacentor variabilis, suggesting that voraxinα is conserved in different tick genera. Quantitative RT-PCR and Western blotting analysis showed that male voraxinα was predominantly expressed in testis and its expression was induced by blood feeding. R. appendiculatus voraxinα was not secreted into the host during tick feeding and was detected in mated female hemolymph as measured by Western blotting. Preliminary vaccination of rabbits with r-voraxinα elicited the humoral immunity and conferred protective immunity against female ticks, resulting in the reduced fed weight. These results suggest that r-voraxinα could be a good candidate as anti-tick vaccine.     

Genetic analysis of ticks belonging to the Rhipicephalus sanguineus group in Latin America

Phylogenetic analyses based on mitochondrial 16S rDNA sequences were generated from Rhipicephalus sanguineus group specimens collected in 29 localities among 9 Latin-American countries, plus ticks collected in South Africa, Spain, and Italy. Sequences from Latin America generated six different haplotypes (A, B, C, D, E, and F). Phylogenetic analyses generated trees that segregated our tick sequences into two distinct clades: one is represented by haplotypes A–C, and South African R. sanguineus and Rhipicephalus turanicus ticks; the second clade is represented by haplotypes D–F, and European R. sanguineus and R. turanicus ticks. When haplotypes A–F are plotted in the Latin America map according to their geographical coordinates, it is clearly seen that haplotypes D–F are restricted to the southern portion of this continent, whereas haplotypes A–C are distributed in areas between northern Mexico and Brazil (except for the extreme south of this last country, where haplotype E was present). Hence, our phylogenetic analyses separated New World specimens of R. sanguineus into two distinct clades, one represented by tropical and subtropical populations (haplotypes A–C), here designated as the ‘tropical’ species. On the other hand, haplotypes D–F are here designated as the ‘temperate’ species because of their distribution in the southern portion of South America. Until recently, it was assumed that the R. sanguineus group was represented by a single species in the New World, namely R. sanguineus. While the present results coupled with recent studies support the presence of at least two species under the taxon R. sanguineus in the New World, they also show that even in the Old World, the taxon R. sanguineus might be represented by more than one species, since our phylogenetic analysis segregated European and South African R. sanguineus ticks into two distinct clades. The same can be applied for Spanish and South African R. turanicus.     

Bovine anaplasmosis and tick‐borne pathogens in cattle of the Galapagos Islands

A cross‐sectional study was conducted to determine the species of Anaplasma spp. and estimate its prevalence in cattle of the three main cattle‐producing Galapagos Islands (Santa Cruz, San Cristóbal and Isabela) using indirect PCR assays, genetic sequencing and ELISA . Ticks were also collected from cattle and scanned for 47 tick‐borne pathogens in a 48 × 48 real‐time PCR chip. A mixed effects logistic regression was performed to identify potential risk factors explaining Anaplasma infection in cattle. A. phagocytophilum was not detected in any of the tested animals. Genetic sequencing allowed detection of A. platys ‐like strains in 11 (36.7%) of the 30 Anaplasma spp.‐positive samples analysed. A. marginale was widespread in the three islands with a global between‐herd prevalence of 100% [89; 100]_95%CI and a median within‐herd prevalence of 93%. A significant association was found between A. marginale infection and age with higher odds of being positive for adults (OR = 3.3 [1.2; 9.9]_{95% Bootstrap CI} ). All collected ticks were identified as Rhipicephalus microplus. A. marginale , Babesia bigemina , Borrelia theileri and Francisella ‐like endosymbiont were detected in tick pools. These results show that the Galapagos Islands are endemic for A. marginale .     

The Emergence of Theileria parva in Jonglei State,South Sudan: Confirmation Using Molecular and Serological Diagnostic Tools

A cross‐sectional survey was carried out in four counties of Jonglei State, South Sudan, between May and June 2012 to determine the distribution and northern limit of Theileria parva, the causative agent of East Coast fever in cattle, and its tick vector Rhipicephalus appendiculatus, as a prerequisite to the deployment of relevant control strategies. A total of 1636 ticks, 386 serum samples and 399 blood samples were collected from indigenous, apparently healthy, cattle of different age groups. Tick species were identified morphologically, and the identity of R. appendiculatus was confirmed by DNA barcoding. Overall, the T. parva infection rate in R. appendiculatus was 25% as shown by nested PCR. ELISA was used to assess antibodies to T. parva, and the overall seroprevalence was 22.8%. PCR of the blood samples showed 55 (13.8%) were positive for T. parva. This is the first molecular confirmation of T. parva DNA in areas north of Juba, where it was previously known and established. The northern limit of T. parva was determined as N⁰06.17.792, about 242 Km north from Juba. Implication of this limit on the epidemiology and control of ECF is discussed.     

Protection against Boophilus annulatus infestations in cattle vaccinated with the B. microplus Bm86-containing vaccine Gavac

Tick infestations by Boophilus spp. constitute a major problem for the cattle industry in tropical and subtropical areas of the world. The use of traditional control methods has been only partially successful and tick infestations remain a serious problem. Recently, the gut antigen Bm86 was isolated from B. microplus. Recombinant preparations of this antigen have been used in vaccines for the control of B. microplus infestations. However, in several regions of the world, B. microplus coexists with other Boophilus species, mainly B. annulatus and B. decoloratus. Therefore, there is a need for the simultaneous control of infestations by different Boophilus species. To test the capacity of the P. pastoris-derived Bm86 antigen preparation (Gavac, Heber Biotec S.A., Havana) to control B. annulatus infestations, controlled experiments were conducted in Mexico and Iran. Cattle were vaccinated with Gavac or not vaccinated and then artificially infested with B. annulatus larvae. The results showed for the first time a high protection efficacy (>99.9%) of Gavac in the control of B. annulatus infestations. These results support the application of Bm86-containing vaccines for the control of Boophilus spp. infestations.     

我国常见蜱的生物学特性及其传播疾病研究进展

蜱是以吸食动物血液为生的寄生生物,可以传播多种病原体,引起宿主患病。我国蜱种多样,分布广泛,多种蜱具有医学重要性。现就我国常见蜱种的生物学特性及其可传播疾病作一综述。     

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.     

气候变化对我国微小扇头蜱分布区的影响

目的　分析影响我国微小扇头蜱地理分布的环境因子及微小扇头蜱在我国的潜在适生区,分析气候变化对我国微小扇头蜱分布的影响。方法　检索我国微小扇头蜱地理分布相关的国内外公开发表文献,提取地理位置信息。结合环境因子,应用ArcGIS 10.7软件和最大熵模型,对微小扇头蜱在我国的适生区分布和影响其分布的主导环境因子进行预测。结果　影响我国微小扇头蜱地理分布的主要气候因子中,贡献率> 10%的因子主要包括年平均降水量（38.2%）、最冷季度平均温度（28.4%）和最干月降水量（14.2%）。微小扇头蜱主要分布于我国南方地区,高、中、低适生区面积分别占我国国土面积的8.6%、13.1%和10.5%。最大熵模型预测结果表明,在2070年RCP 4.5气候条件下,全国微小扇头蜱适生区面积将增加39.98万km2,新增适生区主要位于甘肃省、宁夏回族自治区、青海省、河北省、陕西省、辽宁省、内蒙古自治区、山东省、四川省、西藏自治区等局部地区。质心转移结果表明,从当前到2070年,全国微小扇头蜱适生区整体向北方扩增。结论　气候变化影响我国微小扇头蜱分布区,年平均降水量可能是影响其分布的关键因素之一。     

上海市犬体表媒介蜱寄生情况初步调查

目的初步了解上海市犬体表蜱虫寄生情况。方法2011年3-12月,在上海市18个区(县)采用动物体表采集法捕获犬体表蜱类样本,将蜱虫样本带回实验室,在解剖显微镜下观察成蜱形态,通过形态学鉴定蜱种类。结果在上海市18个区(县)共调查犬1 950只,其中在嘉定、闵行、浦东、松江、黄浦、金山6个区的犬体表共捕获蜱虫328只,经实验室鉴定分为2属2种;宠物犬体表寄生的蜱种为血红扇头蜱和长角血蜱,实验犬和警犬体表寄生的蜱种为血红扇头蜱。结论血红扇头蜱是上海市犬体表寄生的优势蜱种,长角血蜱是新发现的寄生于上海市犬体表的硬蜱蜱种;应加强对媒介蜱的防控。