Abstract
BackgroundTick salivary constituents antagonize inflammatory, immune and hemostatic host responses, favoring tick blood feeding and the establishment of tick-borne pathogens in hosts during hematophagy. Amblyomma triste, A. cajennense and A. parvum ticks are very important in veterinary and human health because they are vectors of the etiological agents for several diseases. Insights into the tick salivary components involved in blood feeding are essential to understanding vector-pathogen-host interactions, and transcriptional profiling of salivary glands is a powerful tool to do so. Here, we functionally annotated the sialotranscriptomes of these three Amblyomma species, which allowed comparisons between these and other hematophagous arthropod species.MethodsmRNA from the salivary glands of A. triste, A. cajennense and A. parvum ticks fed on different host species were pyrosequenced on a 454-Roche platform to generate four A. triste (nymphs fed on guinea pigs and females fed on dogs) libraries, one A. cajennense (females fed on rabbits) library and one was A. parvum (females fed on dogs) library. Bioinformatic analyses used in-house programs with a customized pipeline employing standard assembly and alignment algorithms, protein databases and protein servers.ResultsEach library yielded an average of 100,000 reads, which were assembled to obtain contigs of coding sequences (CDSs). The sialotranscriptome analyses of A. triste, A. cajennense and A. parvum ticks produced 11,240, 4,604 and 3,796 CDSs, respectively. These CDSs were classified into over 100 distinct protein families with a wide range of putative functions involved in physiological and blood feeding processes and were catalogued in annotated, hyperlinked spreadsheets. We highlighted the putative transcripts encoding saliva components with critical roles during parasitism, such as anticoagulants, immunosuppressants and anti-inflammatory molecules. The salivary content underwent changes in the abundance and repertoire of many transcripts, which depended on the tick and host species.ConclusionsThe annotated sialotranscriptomes described herein richly expand the biological knowledge of these three Amblyomma species. These comprehensive databases will be useful for the characterization of salivary proteins and can be applied to control ticks and tick-borne diseases.Electronic supplementary materialThe online version of this article (doi:10.1186/1756-3305-7-430) contains supplementary material, which is available to authorized users.
Highlights
Tick salivary constituents antagonize inflammatory, immune and hemostatic host responses, favoring tick blood feeding and the establishment of tick-borne pathogens in hosts during hematophagy
As A. triste ticks were evaluated in four parasitological conditions, salivary glands (SGs) samples generated four pools designed NGP1 (47 nymphs fed on guinea pigs during first infestation) and NGP2 (90 nymphs fed on guinea pigs during second infestation) to designate the semi-engorged nymph samples; Amblyomma triste females fed on naïve dogs (FD1) (87 females fed on dogs during first infestation) and FD2 (47 females fed on dogs during second infestation) to designate the semi-engorged female samples
Overview of the annotated sialotranscriptomes of A. triste, A. parvum and A. cajennense ticks We generated and analyzed the transcriptional profile of salivary glands (SG) from three neotropical hard ticks belonging to the Amblyomma genus, obtained from six 454-based RNA-seq libraries: one library from A. parvum female ticks fed on dogs, one library from A. cajennense female ticks fed on rabbits and four libraries from A. triste ticks
Summary
Tick salivary constituents antagonize inflammatory, immune and hemostatic host responses, favoring tick blood feeding and the establishment of tick-borne pathogens in hosts during hematophagy. A. cajennense and A. parvum ticks are very important in veterinary and human health because they are vectors of the etiological agents for several diseases. There are 130 species of hard ticks of the genus Amblyomma (Acari: Ixodidae) [4], which has considerable medical and veterinary importance in the Americas and the Caribbean [5]. Due to its low parasitic specificity, it infests cattle, dogs, birds, capybaras [8,9,10] and humans [11] in the urban and peri-urban areas of Brazil, and it is the vector for Rickettsia rickettsii, the causative agent of spotted fever in South America [12]. Recent mitochondrial and nuclear DNA analyses suggest that A. cajennense is a complex of six species, such that A. sculptum is synonymous with A. cajennense ticks found in the coastal and central-western regions of Brazil [13,14]
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