Comparative vaccination of cattle against Boophilus microplus with recombinant antigen Bm86 alone or in combination with recombinant Bm91

Cattle were vaccinated either with a single recombinant tick antigen, Bm86 or with a combination of two recombinant antigens, Bm86 and Bm91 from the tick Boophilus microplus . In three experiments, the responses of cattle to subsequent challenge with the tick were assessed. The addition of the Bm91 antigen enhanced the efficacy of the vaccination over that with Bm86 alone to a statistically significant degree. Moreover, co-vaccination with two antigens did not impair the response of cattle to the Bm86 antigen. Finally, responses of individual cattle to the two antigens were independent. All of these results may be relevant to the increase in efficacy expected from a dual antigen vaccine.     

微小牛蜱凝血酶抑制剂的分离纯化与活性研究

从半饱吸血的微小牛蜱(Boophilusmicroplus)唾液腺中分离纯化到了一种凝血酶抑制剂,用飞行质谱测定该抑制剂的分子量为6752Da,不同于已知的从蜱类来源的丝氨酸蛋白酶抑制剂。这是世界上首次报道的从微小牛蜱唾液腺分离出来的凝血酶抑制剂。该抑制剂对凝血酶表现强烈的抑制活性,对激活的第X因子和胰蛋白酶具有微弱的抑制活性。     

Ultrastructural Analysis of the Oocytes of Female Rhipicephalus sanguineus (Latreille, 1806) (Acari: Ixodidae) Ticks Subjected to the Action of Azadirachta indica A. Juss (Neem)

The present study provides ultrastructural information about the acaricidal effects of neem (Azadirachta indica A. Juss) on the ovaries of R. sanguineus engorged females. In general, the main damage caused in the oocytes was alteration in the shape of the cell and of the germinal vesicle, ring-shaped nucleolus, cytoplasmic vacuolation, and disorganization of the organelles and of the cell membranes (including the chorion), all of which indicate that these cells could be in the process of death. The results showed that azadirachtin would be an efficient acaricide agent for inhibiting and/or neutralizing the reproduction process of R. sanguineus females, impairing the reproductive ability of this species.     

Monoclonal antibody neutralizes the sporozoite stage of different Theileria parva stocks

Summary Monoclonal antibodies were raised against sporozoites of Theileria parva. One of these antibodies (MAbDi) neutralized the infectivity of sporozoites for lymphocytes in vitro and for cattle in vivo. Neutralization seemed to occur by blocking sporozoite entry into the cell. MAbDi neutralized sporozoites of four unrelated stocks of T. parva , indicating the presence of a common antigenic determinant which may be important in initiating protective immunity.     

微小牛蜱磷酸丙糖异构酶基因片段的克隆与原核表达

为克隆和表达微小牛蜱磷酸丙糖异构酶(triosephosphate isomerase,Tim)编码基因,提取微小牛蜱成虫总RNA,采用RT-PCR方法扩增目的基因,将其连入pMD-18T载体,经酶切和测序鉴定后,将正确的目的基因与pET-28a表达载体连接,并转入大肠埃希菌(E.coli)Rosetta(DE3)中,异丙基-β-D-硫代半乳糖苷(IPTG)诱导表达后,经十二烷基硫酸钠-聚丙烯酰胺凝胶电泳(SDS-PAGE)鉴定分析。结果发现,克隆所得的微小牛蜱成虫tim基因片段长度为750bp(登录号为JX112888),其中开放阅读框为750 bp,编码249个氨基酸,与微小牛蜱胚胎中克隆出的tim基因序列的同源性为99%。SDS-PAGE结果显示,重组蛋白Tim相对分子质量(Mr)约为27 000。     

从云南蝙蝠及牛蜱中分离出两株森林脑炎病毒

1990年7月从捕自云南省临沦地区的微小牛蜱及大马蟑蝠脑组织中分离出两株病毒。对其进行了理化特性、电子显微镜、交叉血凝抑制、间接免疫荧光、交叉中和等试验的检测鉴定,结果表明这两株病毒为蜱媒森林脑炎病毒。对我省森林脑炎流行病学的研究具有重要参考价值。     

Heterogeneity in the effect of different ixodid tick species on human natural killer cell activity

Tick saliva plays a vital role in blood-feeding, including manipulation of the host response to tick infestation. Furthermore, a diverse number of tick-borne pathogens are transmitted to vertebrate hosts via tick saliva, some of which exploit the immunomodulatory activities of their vector's saliva. We report that salivary gland extracts (SGE) derived from Dermacentor reticulatus adult ticks induce a decrease in the natural killer (NK) activity of effector cells obtained from healthy human blood donors. The decrease was observed with SGE from both female and male D. reticulatus fed for either 3 or 5 days on mice, but no significant effect was observed with SGE from unfed ticks or ticks that had fed for 1 day. These results indicate that the tick anti-NK factor(s) is only active after blood-feeding has commenced. Microscopic examination revealed that the first step of NK activity, namely effector/target cell conjugate formation, was affected by SGE. The observed reduction in conjugate formation occurred when effector (but not target) cells were treated with SGE for 30 min, and the effect persisted after 12 h of treatment. Similar but less potent anti-NK activity was detected for SGE from Amblyomma variegatum and Haemaphysalis inermis. By contrast, SGE derived from Ixodes ricinus and Rhipicephalus appendiculatus female ticks did not decrease NK activity. The apparent absence of such activity in these two important vectors of tick-borne viruses suggests that control of NK cells does not play an important role in promoting virus transmission, at least for these particular species.     

Boutonneuse fever in Portugal: 1995-2000. Data of a state laboratory

From 1995 through 2000, 3239 clinical samples were tested for rickettsiosis at the Center for Vectors and Infectious Diseases Research – National Health Institute in Portugal. Boutonneuse fever due to R. conorii Malish or R. conorii Israel was laboratory confirmed in 374 samples (11.5%). Clinical and epidemiological features are discussed.     

Epidemiological uses of a population model for the tick Rhipicephalus appendiculatus

The spatial and temporal risk of tick-borne disease depends fundamentally on the distribution, abundance and seasonal dynamics of the vector ticks. The latter factor exerts a major quantitative influence on the transmission dynamics of tick-borne parasites. The population model for Rhipicephalus appendiculatus applies throughout the range of this tick in eastern Africa, and predicts all three fundamental risk factors on the basis of the local temperature and rainfall conditions. Satellite imagery can provide more detailed, real-time measures of environmental conditions over extensive areas than climatic data. There is preliminary evidence to suggest that the population model could be driven by satellite-derived surrogates of its climatic predictors, thus providing wide-scale predictive risk maps of theileriosis.     

Humoral immune responses of Hereford cattle vaccinated with midgut antigens of the cattle tick, Boophilus microplus

Vaccination of cattle with midgut membrane (GM) antigen derived from the cattle tick, Boophilus microplus, infected with the adjuvant Quil A, resulted in significant increases in total immunoglobulins, mainly in the IgG1 and IgG2 fractions of the serum. Analysis of the anti-GM antibody levels of vaccinated cattle showed that the levels of IgG, IgG1 and complement-fixing antibodies were significantly correlated to protection against infestation with cattle ticks. Anti-GM antibodies of the IgG2 and IgM isotype were not correlated to protection against infestation with cattle ticks. Anti-GM antibodies fixed complement (C') in the presence of GM, larval membrane antigen and live, midgut cells, but not in the presence of live, larval cells. Anti-GM antibodies were able to fix C' equally well in the presence of GM antigen and live, midgut cells. None of the antigens tested activated the alternate pathway of complement under the conditions tested. Levels of anti-GM IgG1 antibodies were used to develop a regression model for predicting levels of protection against infestation with cattle ticks in vaccinated cattle.