The effect of the control of endo- and ectoparasites on weight gains in crossbred cattle (<Emphasis Type="Italic">Bos taurus taurus</Emphasis> × <Emphasis Type="Italic">Bos taurus indicus</Emphasis>) in the central region of Brazil

Endo- and ectoparasite infections are among the most important causes of disease and production losses in beef cattle in tropical and subtropical regions. Nevertheless, most treatments are given without epidemiological information and without evaluating their effect on the development of the animals. In this work we present the results of a study of the effect of treatments against endo- and ectoparasites in crossbred steers, during three cycles of field trials in the Brazilian Cerrado region. Three anthelmintic treatments during the winter and three acaricidal treatments during the spring/summer provided significant additional weight gain in three and two experimental trials, respectively. In the trials, steers treated for gastrointestinal nematodes gained a mean of 33 kg more and those treated for ectoparasites had additional mean weight gains of 13 kg compared with non-treated steers.     

中国七省(区)牛蜱的种类鉴定及其携带无形体的分子检测

为了确定牛体表寄生硬蜱的种类及其携带无形体的状况,从河南、湖南、海南、四川、贵州、广东和广西采集牛体表寄生硬蜱572只,通过形态学和分子生物学方法对硬蜱进行种类鉴定;同时用PCR方法检测硬蜱体中无形体感染情况。经形态学和分子生物学鉴定,结果 572只牛硬蜱均为微小扇头蜱,且存在A、B、C等3个分支。基于无形体的16S rRNA基因序列分析的结果表明,微小扇头蜱携带无形体,其阳性率为38.8%(222/572),其中边缘无形体、山羊无形体、扁平无形体和嗜吞噬细胞无形体分别为23.6%(135/572)、7.3%(15/572)、5.3%(42/572)、2.6%(30/572),仅在湖南的牛蜱中发现存在无形体混合感染情况。微小扇头蜱C分支的发现尚属首次,且以边缘无形体感染率最高。     

微小牛蜱Bm86基因的克隆与原核表达

根据已发表的Bm86基因序列,设计表达型引物,利用RT-PCR技术,从微小牛蜱饥饿幼蜱的研磨物中扩增Bm86基因,将PCR产物连入pGEM-T Easy载体,构建重组克隆载体pGEM-T easy-Bm86.测序分析表明:克隆的微小牛蜱Bm86基因序列与GenBank上登录的Bm86基因的核苷酸和氨基酸序列的同源性分别为97%和95.6%.然后对重组克隆载体pGEM-T easy-Bm86进行双酶切,获得带有粘性末端的Bm86基因片段,并将此片段定向亚克隆入原核表达载体pGEX-4T-1,构建重组原核表达载体pGEX-4T-1-Bm86,将其转化到BL21宿主菌中,用IPTG进行诱导表达.SDS-PAGE检测表明表达产物为分子量为88 Ku的融合蛋白,目的蛋白约占蛋白总量的39%,表达量约为1.08 mg/mL.Western blot分析表明此表达产物能被兔抗微小牛蜱阳性血清所识别.     

Distribution and Identification of Ixodid Tick Species on Livestock in Northern Pakistan

Identification of lxodid tick species on livestock in two districts, viz., D.I. Khan and Lakki Marwat of Northern Pakistan were made during the period from March to November 2009 through animals＇ survey and questionnaire. The main tick species were Amblyomma （14.3%）, Boophilus microplus （l 8.5%） and Hyalomma anatolicum and H. dromedarii （67.2%）. Out of 3009 collected ticks, the highest number of female （88.7%） and the lowest of males （ l 1.3%） belong to Boophilus; the lowest number of female （92.4%） and the highest of males （77.5%） belong to Amblyomma. However, cows were more susceptible than buffaloes and camels ranked third to ticks infestation. Moreover, cows, buffalos, goats and sheep harbored mixed infestation （had more than one type of ticks）, however, camels and donkey harbored single infestation （had only one type of tick）. An emerging ethno-veterinary or traditional remedy is poultry keeping for ticks＇ elimination in Lakki Marwat. The results of this research will be helped in taking appropriate measures to reduce tick infestation and to improve management practices. Hence, it will help to increase farm productivity and farmers income.     

Application of PCR assays to determine the genotype of Babesia bovis parasites isolated from cattle with clinical babesiosis soon after vaccination against tick fever

OBJECTIVE: To demonstrate the value of PCR assays to determine the genotypes of Babesia bovis in cattle with clinical signs of babesiosis within 3 weeks after vaccination against tick fever. DESIGN: Samples from 5 cases of babesiosis in cattle soon after vaccination against tick fever were analysed in two PCR assays. PROCEDURE: Parasite DNA was purified from blood taken from cattle with signs of babesiosis within 3 weeks of vaccination against tick fever. DNA was also prepared from the tissues of animals that died of babesiosis. Two PCR assays that amplify repeat sequences of DNA within the B bovis genes, Bv80 and BvVA1, were used to differentiate the genotypes of field isolates and vaccine strains of B bovis. RESULTS: One of the five cases of babesiosis was found to be caused by a vaccine strain, but PCR analyses showed that the predominant isolate in the other four cases was not the vaccine strain. CONCLUSIONS: PCR assays on the DNA of B bovis obtained from the blood or tissues of cattle clinically affected with tick fever within 3 weeks after vaccination are useful to distinguish between vaccine strains and field isolates as the source of infection.     

微小牛蜱Bm86基因的真核表达

采用RT-PCR技术从微小牛蜱饥饿幼蜱破解物中扩增到Bm86基因，将其与巴斯德毕赤酵母分泌型表达载体pPlC9K重组构建了重组表达载体pPIC9K-Bm86，测序正确后将其用SacⅠ内切酶线性化后采用电穿孔法转化巴斯德毕赤酵母菌Gs115，经G418抗性筛选高拷贝重组菌株后用甲醇诱导表达，SDSPAGE和Western-blotting分析结果表明，诱导表达的培养上清液中表达出具有反应活性的68ku重组Bm86蛋白，目的蛋白约占培养上清液中蛋白总量的32％以上，诱导96h目的蛋白的表达量为0．36mg／mL。     

微小牛蜱一个抗菌多肽编码基因的克隆和表达

为了进行抗蜱及蜱传病疫苗的研究,本研究根据微小牛蜱巴西株报道的一种抗菌多肽核苷酸序列设计引物,从微小牛蜱中国安徽株克隆到该抗菌多肽基因,全长383bp,编码110个氨基酸残基,该蛋白预测的分子量为12.2ku,等电点为4.87.经同源性比较,该微小牛蜱巴西株抗菌多肽基因有100%的相同性.经RT-PCR分析表明,该基因在微小牛蜱卵、幼蜱、半饱血雌蜱、饱血雌蜱和雄蜱这几个阶段均有表达.将该基因亚克隆到pET-28a( )表达载体,转化BL21(DE3)宿主菌,经IPTG诱导,可成功表达.重组融合蛋白大小为15ku左右,与预期大小一致.初步体外抗菌试验表明,重组蛋白具有一定的抗菌活性.Western-blot显示,兔抗微小牛蜱唾液抗体能够识别重组表达蛋白.     

An estimate of the economic effects of cattle tick (Boophilus microplus) infestation on Queensland dairy farms

OBJECTIVE: To establish the cost to the Queensland dairy industry of cattle tick infestation and its control, excluding the costs incurred from control measures directed specifically at tick fever and morbidity and mortality arising from tick fever. STUDY DESIGN: Economic models are described that have been based on empirical data relating to liveweight and milk yield loss, and on a survey of control practices and tick infestation. The first two models were designed to estimate costs of control and losses resulting from tick infestation on a single dairy farm. The third model developed estimates of the cost of tick infestation for each of four regions within the tick-infested area of Queensland. RESULTS: The overall cost to the Queensland dairy industry of the cattle tick (excluding the costs associated specifically with tick fever) and based on 1998 management practices, was $4,096,000 per annum. About 49% of this cost was related to the costs of control and 51% to losses in production. CONCLUSION: Cattle tick infestation represents a significant impost on dairy producers in Queensland, and although the actual cost will change as deregulation results in economic changes in the industry, infestations of ticks will continue to be expensive to control.     

Vaccine potential of a tick vitellin-degrading enzyme (VTDCE)

VTDCE (Vitelin-Degrading Cysteine Endopeptidase) is a peptidase with an active role in Rhipicephalus (Boophilus) microplus embryogenesis. VTDCE is found in the tick's eggs and was shown to be the most active protein in vitellin (VT) hydrolysis of the three peptidases already characterized in R. microplus eggs (Boophilus Yolk pro-cathepsin (BYC), Tick Heme Binding Aspartic Proteinase (THAP) and VTDCE). VTDCE activity was assessed in vitro using the natural substrate and a synthetic substrate (N-Cbz-Phe-Arg-MCA). The activity was inhibited by anti-VTDCE antibodies. In the present study, it was shown that VTDCE acts differently from BYC and THAP in VT hydrolysis and that the vaccination of bovines with VTDCE induces a partial protective immune response against R. microplus infestation. Immunized bovines challenged with R. microplus larvae presented an overall protection of 21%, and a reduction in the weight of fertile eggs of 17.6% was observed. The data obtained indicate that VTDCE seems to be important for tick physiology, and that it induces partial protective immune response when inoculated in bovines. This suggests that VTDCE can be useful to improve the protective capacity observed for other antigens.