Vaccinomics Approach to Tick Vaccine Development
Ticks are blood-feeding arthropod ectoparasites that transmit disease-causing pathogens to humans and animals worldwide. Vaccines using tick antigens have proven to be cost-effective and environmental friendly for the control of vector infestations and pa
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Introduction Ticks are blood-feeding arthropod ectoparasites that transmit disease causing pathogens to humans and animals worldwide [1– 3]. Tick–host–pathogen interactions have evolved trough dynamic processes involving genetic traits of hosts, pathogens and ticks that mediate their development and survival [2–4]. In the early 1990s, a cost-effective alternative for cattle tick (Rhipicephalus microplus and R. annulatus) control became commercially available with BM86-based tick antigen vaccines reducing the use of acaricides and the problems associated with them such as selection of acaricide-resistant ticks and the contamination of the environment and animal products with pesticide residues [5]. However, new vaccines are needed for efficient control of vector infestations and pathogen infection and transmission [6]. Vaccinomics is based on the integration of “omics” technologies such as immunogenomics, transcriptomics, and proteomics with systems biology and bioinformatics for the development of next-generation vaccines [7]. As described here, the integration of various omics technologies towards discovering candidate tick protective antigens is important for development of next-generation tick vaccines. As a model we used the deer tick, Ixodes scapularis, and the transmitted pathogenic rickettsia, Anaplasma phagocytophilum, the causative agent of human, canine, and equine granulocytic anaplasmosis and tick-borne fever of ruminants.
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Materials All reagents used for buffer preparations need to be of analytical grade. The solutions are prepared with ultrapure water and stored at 4 °C, except for the solutions containing SDS that are stored at
Sunil Thomas (ed.), Vaccine Design: Methods and Protocols, Volume 2: Vaccines for Veterinary Diseases, Methods in Molecular Biology, vol. 1404, DOI 10.1007/978-1-4939-3389-1_19, © Springer Science+Business Media New York 2016
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20 °C to avoid detergent precipitation. Reagents for protein digestions and mass spectrometry analysis need to be of liquid chromatography–mass spectrometry (LC-MS) grade. 2.1
Tick Samples
Ticks are collected after feeding on vertebrate hosts, including both domestic and wild animals. After repletion, ticks are processed 1–3 h after collection. In some cases, ticks could be stored at −20 °C or in 70 % ethanol at 4 °C until processed (see Note 1). I. scapularis ticks are obtained from laboratory colonies. Larvae and nymphs are fed on rabbits and adults are fed on sheep. Off-host ticks are maintained in a 12 h light: 12 h dark photoperiod at 22–25 °C and 95 % relative humidity. Ticks are infected with A. phagocytophilum by feeding on a sheep inoculated intravenously with A. phagocytophilum (human NY18 isolate)-infected HL-60 cells [8]. Ticks (N = 100–500) are removed from the sheep 7 days after infestation, held in the humidity chamber for 4 days and dissected for DNA, RNA and protein extraction from whole internal tissues (nymphs) or midguts and salivary glands (adult females). Uninfected ticks are prepared in
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