Dataset Information

Proteomics informed by transcriptomics for a qualitative and quantitative analysis of the sialoproteome of adult Ornithodoros moubata ticks.

ABSTRACT:

Background

The argasid tick Ornithodoros moubata is the main vector in mainland Africa of African swine fever virus and the spirochete Borrelia duttoni, which causes human relapsing fever. The elimination of populations of O. moubata would contribute to the prevention and control of these two serious diseases. Anti-tick vaccines are an eco-friendly and sustainable means of eliminating tick populations. Tick saliva forms part of the tick-host interface, and knowledge of its composition is key to the identification and selection of vaccine candidate antigens. The aim of the present work is to increase the body of data on the composition of the saliva proteome of adult O. moubata ticks, particularly of females, since in-depth knowledge of the O. moubata sialome will allow the identification and selection of novel salivary antigens as targets for tick vaccines.

Methods

We analysed samples of female and male saliva using two different mass spectrometry (MS) approaches: data-dependent acquisition liquid chromatography-tandem MS (LC-MS/MS) and sequential window acquisition of all theoretical fragment ion spectra-MS (SWATH-MS). To maximise the number of proteins identified, a proteomics informed by transcriptomics analysis was applied using the O. moubata salivary transcriptomic dataset previously obtained by RNA-Seq.

Results

SWATH-MS proved to be superior to LC-MS/MS for the study of female saliva, since it identified 61.2% more proteins than the latter, the reproducibility of results was enhanced with its use, and it provided a quantitative picture of salivary components. In total, we identified 299 non-redundant proteins in the saliva of O. moubata, and quantified the expression of 165 of these in both male and female saliva, among which 13 were significantly overexpressed in females and 40 in males. These results indicate important quantitative differences in the saliva proteome between the sexes.

Conclusions

This work expands our knowledge of the O. moubata sialome, particularly that of females, by increasing the number of identified novel salivary proteins, which have different functions at the tick-host feeding interface. This new knowledge taken together with information on the O. moubata sialotranscriptome will allow a more rational selection of salivary candidates as antigen targets for tick vaccine development.

SUBMITTER: Oleaga A

PROVIDER: S-EPMC8356541 | biostudies-literature |

REPOSITORIES: biostudies-literature

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Project description:BackgroundThe argasid tick Ornithodoros erraticus is the main vector of tick-borne human relapsing fever (TBRF) and African swine fever (ASF) in the Mediterranean Basin. The prevention and control of these diseases would greatly benefit from the elimination of O. erraticus populations, and anti-tick vaccines are envisaged as an effective and sustainable alternative to chemical acaricide usage for tick control. Ornithodoros erraticus saliva contains bioactive proteins that play essential functions in tick feeding and host defence modulation, which may contribute to host infection by tick-borne pathogens. Hence, these proteins could be candidate antigen targets for the development of vaccines aimed at the control and prevention of O. erraticus infestations and the diseases this tick transmits. The objective of the present work was to obtain and characterise the proteome of the saliva of O. erraticus adult ticks as a means to identify and select novel salivary antigen targets.MethodsA proteomics informed by transcriptomics (PIT) approach was applied to analyse samples of female and male saliva separately using the previously obtained O. erraticus sialotranscriptome as a reference database and two different mass spectrometry techniques, namely liquid chromatography-tandem mass spectrometry (LC-MS/MS) in data-dependent acquisition mode and sequential window acquisition of all theoretical fragment ion spectra MS (SWATH-MS).ResultsUp to 264 and 263 proteins were identified by LC-MS/MS in the saliva of O. erraticus female and male ticks, respectively, totalling 387 non-redundant proteins. Of these, 224 were further quantified by SWATH-MS in the saliva of both male and female ticks. Quantified proteins were classified into 23 functional categories and their abundance compared between sexes. Heme/iron-binding proteins, protease inhibitors, proteases, lipocalins and immune-related proteins were the categories most abundantly expressed in females, while glycolytic enzymes, protease inhibitors and lipocalins were the most abundantly expressed in males. Ninety-seven proteins were differentially expressed between the sexes, of which 37 and 60 were overexpressed in females and males, respectively.ConclusionsThe PIT approach demonstrated its usefulness for proteomics studies of O. erraticus, a non-model organism without genomic sequences available, allowing the publication of the first comprehensive proteome of the saliva of O. erraticus reported to date. These findings confirm important quantitative differences between sexes in the O. erraticus saliva proteome, unveil novel salivary proteins and functions at the tick-host feeding interface and improve our understanding of the physiology of feeding in O. erraticus ticks. The integration of O. erraticus sialoproteomic and sialotranscriptomic data will drive a more rational selection of salivary candidates as antigen targets for the development of vaccines aimed at the control of O. erraticus infestations and the diseases it transmits.

Project description:Anti-tick vaccines have proved to be an effective and sustainable method for the control of tick infestations and tick-borne diseases with clear advantages over the application of chemical acaricides (Šmit and Postma, 2016; de la Fuente, 2018; Ndawula and Tabor, 2020). Moreover, the efficacy of acaricide application against Ornithodoros ticks is seriously limited owing to their endophilic/nidicolous life style, which make these ticks less accessible to the chemical acaricides (Astigaraga et al., 1995). Success in tick vaccine development is largely dependent on identification of new and highly protective tick antigens. Searching of new candidate protective antigens is currently being approached among tick molecules that play important biological functions at the tick-host interface, and more precisely among the salivary and intestinal proteins involved in biological processes specifically evolved by ticks to adapt to haematophagy (de la Fuente et al., 2016; Oleaga et al., 2021; Pérez-Sánchez et al., 2021). Accordingly, next-generation sequencing (NGS) and high-throughput proteomics technologies are been used to explore the transcriptome and proteome of the salivary glands/saliva and midguts of an increasing number of tick species and obtain the corresponding sialomes and mialomes (Chmelař et al., 2016; Almeida-Martins et al., 2020; Mans et al., 2020; Oleaga et al., 2021). These studies have identified a wealth of tick molecules related to tick haematophagy, tick-host interplay and pathogen transmission, which can then be scrutinized and filtered in vaccinomics pipelines for selecting candidate protective antigens (Chmelař et al., 2016; Maruyama et al., 2017; Antunes et al., 2018; de la Fuente et al., 2018; Ren et al., 2019; Couto et al., 2021). Similarly, we were also interested in characterizing the O. erraticus sialome. As far as O. erraticus saliva must contain all the bioactive molecules that the tick need to successfully feed, decoding its composition will lead to the discovery of new antigen targets for developing vaccines for the control and prevention of O. erraticus infestations and the diseases it transmits. Accordingly, the objective of the present work was to obtain the proteome of the saliva of O. erraticus adult ticks. For this, we have used a proteomics informed by transcriptomics approach to analyse female and male saliva separately using two different mass spectrometry approaches: liquid chromatography-tandem mass spectrometry (LC-MS/MS) in data-dependent acquisition (DDA) mode, and Sequential Window Acquisition of all Theoretical fragment ion spectra Mass Spectrometry (SWATH MS). SWATH MS is a specific variant of data-independent acquisition (DIA) methods that combines deep proteome coverage capabilities with quantitative consistency and accuracy (Ludwig et al., 2018). Here we reported the identification of 387 non-redundant proteins in the saliva of O. erraticus adult ticks as well as a qualitative and quantitative comparison of the saliva protein composition between both sexes. The integration of O. erraticus sialoproteomic and sialotranscriptomic datasets facilitate a better understanding of the physiology of feeding in O. erraticus and will drive the discovery of new and more effective antigen targets for development of anti-tick vaccines.

Project description:IntroductionOrnithodoros erraticus and Ornithodoros moubata are the main vectors of African swine fever virus (ASFV) and the human relapsing fever spirochetes Borrelia hispanica and Borrelia crocidurae in the Mediterranean region and Borrelia duttoni in continental Africa. Manipulation of the tick microbiome has been shown to reduce vector fitness and competence in tick vectors, suggesting that the identification of key microbial players associated with tick tissues can inform interventions such as anti-microbiota vaccines to block pathogen development in the midgut and/or salivary glands.MethodsIn this study, we analyzed and compared the microbiome of the salivary glands and midgut of O. erraticus and O. moubata. For the taxonomic and functional characterization of the tissue-specific microbiome, we used 16S rRNA amplicon sequencing and prediction of metabolic profiles using PICRUSt2. Co-occurrence networks were built to characterize the community assembly and identify keystone taxa in each tick species.ResultsOur results revealed differences in the composition, diversity, and assembly of the bacterial microbiome of salivary glands and midgut within each tick species, but differences were more noticeable in O. moubata. Differences were also found in the microbiome of each tissue, salivary gland and midgut, between species. However, the 'Core Association Networks (CAN)' analysis revealed conserved patterns of interacting taxa in tissues within and between tick species. Different keystone taxa were identified in O. erraticus and O. moubata tissues, but Muribaculaceae and Alistipes were found as keystone taxa in the salivary glands of both tick species which justifies their use as anti-microbiota vaccine candidates to alter the microbiome and reduce tick fitness and/or block pathogen transmission. The high similarity of predicted metabolic pathways profiles between tissues of the two tick species suggests that taxonomic variability of the microbiome is not associated with significant changes in microbial functional profiles.ConclusionWe conclude that the taxonomic structure of the microbiome in O. erraticus and O. moubata is tissue-specific, suggesting niche partitioning of bacterial communities associated to these soft ticks. However, shared keystone taxa and conserved patterns of interacting taxa between tissues and tick species suggest the presence of key microbial players that could be used as anti-microbiota vaccine candidates to affect tick physiology and/or pathogen colonization.