Comparative efficacy of rHaa86 and rBm86 against Hyalomma anatolicum anatolicum and Rhipicephalus (Boophilus) microplus.

Entomology Laboratory, Parasitology Division, Indian Veterinary Research Institute, Izatnagar, Uttar Pradesh, India.
Parasite Immunology (Impact Factor: 2.21). 02/2012; 34(6):297-301. DOI: 10.1111/j.1365-3024.2012.01356.x
Source: PubMed

ABSTRACT Hyalomma anatolicum anatolicum and Rhipicephalus (Boophilus) microplus are the most economically important tick species in India and other tropical and subtropical regions of the world and transmit pathogens causing animal and human diseases. We demonstrated that vaccination of animal by rHaa86 could be used for the control of both H. a. anatolicum and R. (B.) microplus infestations. By comparing the efficacy of rHaa86 and rBm86, it was observed that vaccine based on rHaa86 will be more effective in controlling homologous challenge infestations (68·7% against larvae and 45·8% against adults). The results of this trial demonstrated that species-specific antigens are the better choice for vaccine development and could serve as an effective tool for the integrated control of H. a. anatolicum.

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    ABSTRACT: Tick vaccines are important component of integrated pest management for sustainable control of tick and tick born diseases. Immune responses against rHaa86 (homologue of Bm86) recombinant Hyalomma tick antigen were determined in experimental crossbred calves. The humoral antibody responses of the calves were measured against rHaa86 in an optimized ELISA format. The expression of the interferon gamma (IFN-γ), was also evaluated in the culture supernatant of blood culture from blood samples of the experimental calves. The expression patterns were studied after stimulating the blood cells in vitro with rHaa86 antigen and subsequently optical density was measured against IFN-γ. The results were expressed as stimulation indices. All the rHaa86 immunized animal showed strong humoral antibody response just after 1st vaccination and reach to pick after 2nd booster and thereafter maintained up to days 120 from post primary immunization. The humoral antibody response was dominated by IgG1 against IgG2 throughout the period of antibody monitoring. The standard graph of bovine recombinant IFN-γ was plotted which showed a significant difference in SI and OD value up to 200 pg/ml. The lowest detectable value of IFN-γ was 20 pg/ml and SI at this level is 1.16 which is greater than maximum SI calculated from individual calf. The IFN-γ response never reached at significant level and the IgG1 response was dominated over IgG2 response throughout the period of experiment. Since IgG2 and IFN-γ are interlinked, the present study established the Th2 response as a possible mode of mechanism of conferring antibody mediated protection against challenged ticks.
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    ABSTRACT: The tick Rhipicephalus (Boophilus) microplus is a blood-sucking ectoparasite of cattle that severely impairs livestock production. Studies on tick immunological control address mostly single-antigen vaccines. However, from the commercial standpoint, so far no single-antigen vaccine has afforded appropriate protection against all R. microplus populations. In this context, multi-antigen cocktails have emerged as a way to enhance vaccine efficacy. In this work, a multi-antigenic vaccine against R. microplus was analyzed under field conditions in naturally infested cattle. The vaccine was composed by three tick recombinant proteins from two tick species that in previous single-vaccination reports provided partial protection of confined cattle against R. microplus infestations: vitellin-degrading cysteine endopeptidase (VTDCE) and boophilus yolk pro-cathepsin (BYC) from R. microplus, and glutathione S-transferase from Haemaphysalis longicornis (GST-Hl). Increased antibody levels against three proteins were recorded after immunizations, with a distinct humoral immune response dynamics for each protein. Compared to the control group, a statistically significant lower number of semi-engorged female ticks were observed in vaccinated cattle after two inoculations. This reduction persisted for 3 months, ranging from 35.3 to 61.6%. Furthermore, cattle body weight gain was significantly higher in vaccinated animals when compared to control cattle. Compared to the single-antigen vaccines composed by VTDCE, BYC or GST-Hl, this three-antigen vaccine afforded higher protection levels against R. microplus infestations.
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    ABSTRACT: With an aim to evaluate the protective potentiality of rBm86 against Rhipicephalus (Boophilus) microplus Indian Veterinary Research Institute (IVRI)-I line and Hyalomma anatolicum anatolicum IVRI-II line infestations on crossbred (Bos indicus × Bos taurus) calves, 20 animals of 3 months of age were randomly divided in to four equal groups and maintained in tick-proof conditions. Animals of groups 1 and 2 were immunized with 2 ml of rBm86 (100 μg)-based vaccine (procured from Revetmex S.A. de C.V, Mexico City, Mexico) thrice at 30 days interval. Animals of groups 3 and 4 were kept as negative control and inoculated with PBS only. Each animal of group 1 and 3 was challenged with 7-day-old 50 unfed adults of H. anatolicum anatolicum (1:1, male and female), and each animal of groups 2 and 4 was challenged with 6-8-day-old R. (B.) microplus larvae obtained from 50 mg of eggs, on 17th day of the last immunization. The efficacy of rBm86 against tick infestations was determined as percentage reduction in number of adults dropped (DT%), engorged body weight (DR%), egg masses (DO%), and immunogen efficacy (E%). The calculated data were 11.8, 10.8, 15.0, and 25.1 %, respectively, for DT, DR, DO, and E% against H. anatolicum anatolicum infestation, while in the case of R. (B.) microplus infestation, the corresponding data were 6.4, 11.24, 40.7, and 44.5 %, respectively. The results indicated partial effectiveness of rBm86 antigen(s) in imparting protection against homologous and heterologous challenge infestations of Indian ticks. The results indicated identification of more effective antigen(s) for the development of vaccine against economically important tick species in India.
    Parasitology Research 03/2012; 111(2):629-35. · 2.85 Impact Factor

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