Project description:In Europe, ticks are the most important vectors of diseases threatening humans, livestock, wildlife and companion animals. Nevertheless, genomic sequence information and functional annotation of proteins of the most important European tick, Ixodes ricinus, is limited. Here we present the first analysis of the I. ricinus genome and of the transcriptome of the unfed I. ricinus midgut. We combined and integrated data from genome, transcriptome and proteome. The de novo assembly of 1 billion paired-end sequences identified 6,415 putative genes providing an unprecedented insight into the I. ricinus genome. Mapping of our midgut mRNA reads to the assembled contigs let us estimate to cover around two third of the unique genomic sequences. In addition, more than 10,000 transcripts from naïve midgut were annotated functionally and/or locally. By combining the alignment-based with a motif-search based annotation approach, we could double the number of annotations throughout all groups without shifting the dataset. Moreover, 1,175 proteins expressed in the naïve midgut were identified by mass spectrometry confirming the high completeness of our transcriptome database, and 608 were significantly annotated for function and/or localization. This multiple-omics study vastly extends the publicly available DNA, RNA and protein databases for I. ricinus and ticks in general.
Project description:Here, we challenged rabbits with repeated feeding of Ixodes ricinus adults and observed the formation of specific antibodies against several tick salivary proteins. To identify the salivary antigens, isolated immunoglobulins from repeatedly infested rabbits were utilised for a pull-down from the saliva of pilocarpine-treated ticks. Eluted antigens were separated on 1D SDS-PAGE and analysed by peptide mass fingerprinting. To increase the authenticity of immunogens identified, we also performed, for the first time, de novo assembly of the sialome from I. ricinus females fed for six days, a timepoint used for pilocarpine-salivation.
Project description:The midgut of the tick is the most important tissue for the storage and digestion of host blood, which serves as the sole source of energy and nutrients for all tick development and reproduction. During feeding at each developmental stage, dynamic changes in the tick midgut epithelium reflect changes in physiological processes in this tissue. In addition, the midgut serves as the primary interface between the tick and tick-borne pathogens, which determines the vector competence of the tick. Several transcriptome data from Ixodes ricinus have been published, but few studies have examined tick proteomes. In contrast to transcriptome data, proteomics provides a deeper understanding of key cellular processes occurring in the investigated tissues. In this work, we present for the first time insight into proteomics of the midgut of I. ricinus nymph. Label-free quantitative proteomics was used to elucidate changes during blood meal and development in I. ricinus. A total of 1 534 I. ricinus-specific proteins were identified, with only a few host proteins detected. In addition, the proteins involved in the specific physiological processes of the tick were studied in detail to gain better insight into the ontogeny of the midgut of the nymph.
Project description:There has been an emergence and expansion of tick-borne diseases in Europe, Asia and North America in recent years, including Lyme disease, tick-borne encephalitis, and human anaplasmosis. The primary tick vectors implicated are hard ticks of the Ixodes genera. Although much is known about the host response to these bacterial and viral pathogens, there is limited knowledge of the cellular responses to infection within the tick vector. The bacterium Anaplasma phagocytophilum (A. phagocytophilum), is able to bypass apoptotic processes in ticks, enabling infection to proceed. However, the tick cellular responses to infection with the flaviviruses tick-borne encephalitis virus (TBEV) and louping ill virus (LIV), which cause tick-borne encephalitis and louping ill respectively, are less clear. Infection of an Ixodes ricinus (I. ricinus) tick cell line with the viruses LIV and TBEV, and the bacterium A. phagocytophilum, identified activation of common and distinct cellular pathways. In particular, commonly-upregulated genes included those that modulate apoptotic pathways (HSP70), putative anti-pathogen genes (FKBP and XBL1), and genes that influence the tick innate immune response, including selective activation of toll genes. These data provide an insight into potentially key genes involved in the tick cellular response to viral or bacterial infection.