Vaccine 30 (2012) 3453–3458 Contents lists available at ScienceDirect Vaccine journal homepage: www.elsevier.com/locate/vaccine Efficacy of Rhipicephalus (Boophilus) microplus Bm86 against Hyalomma dromedarii and Amblyomma cajennense tick infestations in camels and cattle Manuel Rodríguez-Valle a,∗,1, Amar Taoufik b, Mario Valdés c, Carlos Montero a, Ibrahim Hassan d, Shawgi Mohammed Hassan e, Frans Jongejan b,f, Jose de la Fuente g,h a Centro de Ingenieria Genetic and Biotecnologia, Habana, Cuba b Utrecht Centre for Tick-borne Diseases (UCTD), Faculty of Veterinary Medicine, Utrecht University, Yalelaan 1, 3583 CL Utrecht, The Netherlands c Centro Nacional de Parasitología, San Antonio de los Ba˜nos, Habana, Cuba d Department of Microbiology and Parasitology, University of Nyala, Sudan e Department of Parasitology, University of Khartoum, Sudan f Department of Veterinary Tropical Diseases, Faculty of Veterinary Science, University of Pretoria, PO Box. X04, Onderstepoort 0110, South Africa g Department of Veterinary Pathobiology, Centre for Veterinary Health Sciences, Oklahoma State University, Stillwater, OK 74078-2007, USA h Instituto de Investigación en Recursos Cinegéticos IREC (CSIC-UCLM-JCCM), Ronda de Toledo s/n, 13005 Ciudad Real, Spain article info abstract Article history: The recombinant Bm86-based tick vaccines have shown their efficacy for the control of cattle ticks, Received 5 January 2012 Rhipicephalus (Boophilus) microplus and R. annulatus infestations. However, cattle ticks often co-exist Received in revised form 13 February 2012 with multi-host ticks such as Hyalomma and Amblyomma species, thus requiring the control of multiple Accepted 8 March 2012 tick infestations for cattle and other hosts. Vaccination trials using a R. microplus recombinant Bm86- Available online 22 March 2012 based vaccine were conducted in cattle and camels against Hyalomma dromedarii and in cattle against Amblyomma cajennense immature and adult ticks. The results showed an 89% reduction in the number of Keywords: H. dromedarii nymphs engorging on vaccinated cattle, and a further 32% reduction in the weight of the Rhipicephalus microplus Hyalomma dromedarii surviving adult ticks. In vaccinated camels, a reduction of 27% and 31% of tick engorgement and egg mass Amblyomma cajennense weight, respectively was shown, while egg hatching was reduced by 39%. However, cattle vaccination Tick with Bm86 did not have an effect on A. cajennense tick infestations. These results showed that Bm86 Vaccine vaccines are effective against R. microplus and other tick species but improved vaccines containing new Bm86 antigens are required to control multiple tick infestations. Cattle © 2012 Elsevier Ltd. All rights reserved. Camels 1. Introduction ferent cattle tick strains [9] and in other tick species [10–14] as Bm86 orthologs. During 1993–1997, two vaccines using recom- Bm86 is a membrane-bound glycoprotein on the surface of R. binant Bm86 were registered for use in Latin American countries microplus gut cells [1]. In 1995, the antigen Bm86 was re-cloned (GavacTM) and Australia (TickGARDTM) [6,15–17] and had similar from an Argentinean strain of R. microplus and designated as Bm95 efficacy for the control of cattle tick infestations [18]. These tick [2]. Antibodies produced in vaccinated cattle bind to Bm86 in the vaccines constitute the only example of commercial vaccines for tick gut and are thought to cause damage mainly by the com- the control of ectoparasites and led the way for research on the plement pathway, but this mechanism is still poorly understood development of vaccines for arthropod vectors of pathogens that [3,4]. The result of Bm86 vaccination is the reduction in the num- affect human and animal health [18]. ber and weight of engorged ticks, the egg laying capacity and the In many regions, R. microplus shares its habitat with other Rhipi- egg fertility, which ultimately reduces tick populations and the cephalus tick species such as R. annulatus, R. decoloratus and R. geigyi prevalence of tick-borne pathogens [5–8]. Bm86 is present in dif- and other multi-host tick species such as those belonging to the Hyalomma and Amblyomma genera which are major constraints to animal production in some regions [19–21]. The camel tick, H. dromedarii is a two host tick distributed in ∗ Corresponding author at: Queensland Alliance for Agriculture & Food Innovation the North, North East, East and Sahara-Sahel regions of Africa that (QAAFI), Queensland Biosciences Precinct, The University of Queensland, DEEDI, GPO occasionally uses three hosts [19,22]. Camels are the principal host Box 6097, St Lucia, Qld 4067, Australia. Tel.: +61 0 7 3255 4529. of the H. dromedarii adults with some records also showing that E-mail address: [email protected] (M. Rodríguez-Valle). cattle and goats are also susceptible [23]. The immature stages can 1 306 Carmody Rd (Building 80 Loading Dock, off Services Road), St. Lucia, Qld 4072, Australia. parasitize rodents, leporids, hedgehogs and birds [23]. In addition, 0264-410X/$ – see front matter © 2012 Elsevier Ltd. All rights reserved. doi:10.1016/j.vaccine.2012.03.020 3454 M. Rodríguez-Valle et al. / Vaccine 30 (2012) 3453–3458 H. dromedarii is a vector of bacteria [24], protozoa [25], rickettsia of vaccinated and control cattle was determined by ELISA [36]. The [26], and viruses [27]. In the Americas, Rocky Mountain spotted titres of anti-Bm86 IgG were very high in the vaccinated group after fever caused by Rickettsia rickettsii is transmitted by A. cajennese, the last immunization with Bm86, as it is reported in the literature Dermacentor andersoni, D. variablis and R. sanguineus [28]. The Rick- [17]. ettsia amblyommii is transmitted by A. cajennese in Brazil [29]. Ten weeks after vaccination, a cage containing approximately Recombinant Bm86 continues to be the most effective anti- 1500 H. dromedarii larvae (three months old) was glued onto the gen against tick infestations. The protective efficacy of vaccination back of each calf. Engorged nymphs were collected separately from with Bm86-based vaccines has been shown an effect on the con- each calf and reapplied to the same calves in a similar way. Moulted trol of tick infestations by Hyalomma anatolicum anatolicum, R. unfed adult ticks applied were five months old. Tick infestations annulatus, R. decoloratus and H. dromedarii [10,30–32]. Close to were monitored daily. Engorged adults tick were collected, counted 100% control of R. annulatus infestations has been observed using and weighed. Female ticks were incubated at 28 ◦C and 85% relative Bm86 cattle vaccination in different trials [10,30,31,33]. In contrast, humidity for egg laying and weight. Bm86 has shown partial or no protection against some R. microplus strains from different geographic regions and other tick species 2.3. Experiment 2: Bm86 vaccination against H. dromedarii [10,18,30,34,35]. The effect of Bm86 vaccination against different infestations in camels tick species can be further characterized by conducting trials using Bm86 orthologs on different animal breeds or hosts. Also, the com- Experiment 2 was conducted at the University of Khartoum, bination of different Bm86 orthologs in animal trials could assist Sudan. Seven naïve male camels (Camelus dromedarius) aged 2–2.5 to understand the protective host immune response against tick years old were used in the study. Camels were obtained from a tick infestations. free area geographically localized at the arid zone on the Sahara In this study, vaccination trials were conducted to character- on the northern part of Sudan. Camels were randomly divided into ize the effect of Bm86 vaccination in cattle and camels against H. vaccinated and control groups with four and three animals each, dromedarii and in cattle against A. cajennense immature and adult respectively. Camels were vaccinated with Bm86 while controls ticks. These results expand our knowledge of the effect of Bm86- were not vaccinated. Vaccinated camels received 2 ml intramus- based vaccines in controlling tick infestations and suggest the need cular inoculations of 100 ␮g of recombinant Bm86 in Montanide for Bm86 orthologs or new antigens for the control of multiple tick 888 (GavacTM, Heber Biotec) and equivalent boosters on weeks four species infestations in some regions. and seven. The control group was given phosphate-buffered saline (PBS) solution emulsified in Montanide 888. Ten weeks after the first inoculation, a cotton bag was glued around one ear of each of 2. Materials and methods the camels in both experimental group and 40 laboratory reared unfed H. dromedarii adults (20 females and 20 males two weeks 2.1. Tick species old) were placed in each bag. Ticks were daily checked throughout the feeding period and the fully engorged females that dropped H. dromedarii larvae used in Experiment 1 were originally col- within each cotton bag were collected and immediately weighed. lected from camels in Morocco and maintained at the Faculty of The female ticks were then separately incubated at 28 ◦C and 85% Veterinary Medicine, Utrecht University under controlled condi- relative humidity for egg laying and the weight of individual egg tions at 28 ◦C and 85% relative humidity prior to calf infestation. batches were recorded for each female. Engorged female H. dromedarii were collected at the central live- stock market, Khartoum State, Sudan, and kept feeding on goats 2.4. Experiment 3: Bm86 vaccination against A. cajennense until reared to the subsequent adult stage. Unfed adult ticks were infestations in calves kept in the laboratory prior to the infestation of camels in Experi- ment 2. Experiment 3 was conducted at The Centro Nacional de Par- A colony of A. cajennense was initiated from adult ticks collected asitología, San Antonio de los Banos,˜ Havana, Cuba. Seven naïve from cattle at a farm in Pinar del Río Province of Cuba, in 1999 and calves (Holstein-Friesian) were randomly divided into a vaccinated maintained for 18 months in the Laboratory of the Centro Nacional group containing four cattle (A-46, A-54, V-106 and V-109) and con- de Parasitología, San Antonio de los Banos,˜ Havana, Cuba, on cattle trol group of three calves (R-91, R-94 and R-100).