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Matoušková Z, Orsághová K, Srb P, Pytelková J, Kukačka Z, Buša M, Hajdušek O, Šíma R, Fábry M, Novák P, Horn M, Kopáček P, Mareš M. An Unusual Two-Domain Thyropin from Tick Saliva: NMR Solution Structure and Highly Selective Inhibition of Cysteine Cathepsins Modulated by Glycosaminoglycans. Int J Mol Sci 2024; 25:2240. [PMID: 38396918 PMCID: PMC10889554 DOI: 10.3390/ijms25042240] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/12/2023] [Revised: 02/02/2024] [Accepted: 02/10/2024] [Indexed: 02/25/2024] Open
Abstract
The structure and biochemical properties of protease inhibitors from the thyropin family are poorly understood in parasites and pathogens. Here, we introduce a novel family member, Ir-thyropin (IrThy), which is secreted in the saliva of Ixodes ricinus ticks, vectors of Lyme borreliosis and tick-borne encephalitis. The IrThy molecule consists of two consecutive thyroglobulin type-1 (Tg1) domains with an unusual disulfide pattern. Recombinant IrThy was found to inhibit human host-derived cathepsin proteases with a high specificity for cathepsins V, K, and L among a wide range of screened cathepsins exhibiting diverse endo- and exopeptidase activities. Both Tg1 domains displayed inhibitory activities, but with distinct specificity profiles. We determined the spatial structure of one of the Tg1 domains by solution NMR spectroscopy and described its reactive center to elucidate the unique inhibitory specificity. Furthermore, we found that the inhibitory potency of IrThy was modulated in a complex manner by various glycosaminoglycans from host tissues. IrThy was additionally regulated by pH and proteolytic degradation. This study provides a comprehensive structure-function characterization of IrThy-the first investigated thyropin of parasite origin-and suggests its potential role in host-parasite interactions at the tick bite site.
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Affiliation(s)
- Zuzana Matoušková
- Institute of Organic Chemistry and Biochemistry, Czech Academy of Sciences, Flemingovo n. 2, 16610 Praha, Czech Republic; (Z.M.); (K.O.); (M.B.); (M.F.); (M.H.)
- Department of Biochemistry, Faculty of Science, Charles University, Hlavova 8, 12800 Praha, Czech Republic
| | - Katarína Orsághová
- Institute of Organic Chemistry and Biochemistry, Czech Academy of Sciences, Flemingovo n. 2, 16610 Praha, Czech Republic; (Z.M.); (K.O.); (M.B.); (M.F.); (M.H.)
- First Faculty of Medicine, Charles University, Katerinska 32, 12108 Praha, Czech Republic
| | - Pavel Srb
- Institute of Organic Chemistry and Biochemistry, Czech Academy of Sciences, Flemingovo n. 2, 16610 Praha, Czech Republic; (Z.M.); (K.O.); (M.B.); (M.F.); (M.H.)
| | - Jana Pytelková
- Institute of Organic Chemistry and Biochemistry, Czech Academy of Sciences, Flemingovo n. 2, 16610 Praha, Czech Republic; (Z.M.); (K.O.); (M.B.); (M.F.); (M.H.)
| | - Zdeněk Kukačka
- Institute of Microbiology, Czech Academy of Sciences, Prumyslova 595, 25250 Vestec, Czech Republic
| | - Michal Buša
- Institute of Organic Chemistry and Biochemistry, Czech Academy of Sciences, Flemingovo n. 2, 16610 Praha, Czech Republic; (Z.M.); (K.O.); (M.B.); (M.F.); (M.H.)
| | - Ondřej Hajdušek
- Institute of Parasitology, Biology Centre, Czech Academy of Sciences, Branisovska 31, 37005 Ceske Budejovice, Czech Republic
| | - Radek Šíma
- Institute of Parasitology, Biology Centre, Czech Academy of Sciences, Branisovska 31, 37005 Ceske Budejovice, Czech Republic
- Biopticka Laborator, Mikulasske Namesti 4, 32600 Plzen, Czech Republic
| | - Milan Fábry
- Institute of Organic Chemistry and Biochemistry, Czech Academy of Sciences, Flemingovo n. 2, 16610 Praha, Czech Republic; (Z.M.); (K.O.); (M.B.); (M.F.); (M.H.)
| | - Petr Novák
- Institute of Microbiology, Czech Academy of Sciences, Prumyslova 595, 25250 Vestec, Czech Republic
| | - Martin Horn
- Institute of Organic Chemistry and Biochemistry, Czech Academy of Sciences, Flemingovo n. 2, 16610 Praha, Czech Republic; (Z.M.); (K.O.); (M.B.); (M.F.); (M.H.)
| | - Petr Kopáček
- Institute of Parasitology, Biology Centre, Czech Academy of Sciences, Branisovska 31, 37005 Ceske Budejovice, Czech Republic
| | - Michael Mareš
- Institute of Organic Chemistry and Biochemistry, Czech Academy of Sciences, Flemingovo n. 2, 16610 Praha, Czech Republic; (Z.M.); (K.O.); (M.B.); (M.F.); (M.H.)
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Hajdusek O, Kopacek P, Perner J. Experimental platforms for functional genomics in ticks. CURRENT OPINION IN INSECT SCIENCE 2023; 59:101102. [PMID: 37586557 DOI: 10.1016/j.cois.2023.101102] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/20/2023] [Revised: 08/08/2023] [Accepted: 08/10/2023] [Indexed: 08/18/2023]
Abstract
Ticks are blood-feeding ectoparasites that devastate cattle farming and are an omnipresent nuisance to pets and humans, posing a threat of pathogen transmission. Laboratory experimental models can be instrumental in the search for molecular targets of novel acaricides or vaccines. Mainly, though, the experimental models represent invaluable tools for broadening our basic understanding of key processes of tick blood-feeding physiology and vector competence. In order to understand the function of a single component within the full complexity of a feeding tick, genetic or biochemical interventions are used for systemic phenotypisation. In this work, we summarise current experimental modalities that represent powerful approaches for determining biological functions of tick molecular components.
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Affiliation(s)
- Ondrej Hajdusek
- Institute of Parasitology, Biology Centre of the Czech Academy of Sciences, Branisovska 31, 370 05 Ceske Budejovice, Czech Republic
| | - Petr Kopacek
- Institute of Parasitology, Biology Centre of the Czech Academy of Sciences, Branisovska 31, 370 05 Ceske Budejovice, Czech Republic
| | - Jan Perner
- Institute of Parasitology, Biology Centre of the Czech Academy of Sciences, Branisovska 31, 370 05 Ceske Budejovice, Czech Republic.
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Ma H, Lao Y, Liu S, Ai J, Sun X, Zhang W, Kang M, Li J, Sun Y. The diurnal salivary glands transcriptome of Dermacentor nuttalli from the first four days of blood feeding. Ticks Tick Borne Dis 2023; 14:102178. [PMID: 37001418 DOI: 10.1016/j.ttbdis.2023.102178] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/16/2022] [Revised: 02/25/2023] [Accepted: 03/14/2023] [Indexed: 03/31/2023]
Abstract
The ixodid tick Dermacentor nuttalli is distributed from southern Siberia to North China and is a vector of many pathogens. This species can have severe impacts on animal husbandry and human health. To date, the control of D. nuttalli is limited to the use of acaricides such as organophosphorus, synthetic pyrethroids and amidine pesticides. There are no environmentally friendly or reliable prevention and control measures, and little is known regarding key antigens involved in blood feeding. Salivary glands are major tissues involved in the blood feeding and pathogen transmission of ticks. Therefore, this study focused on salivary glands tissue to identify the dominant antigens of D. nuttalli involved in tick feeding. For this, high-throughput RNA sequencing (RNA-seq) was used for analysis. The transcriptome of female D. nuttalli ticks was assembled and characterized, and differentially expressed genes (DEGs) were identified in the salivary glands of ticks that had not fed (0 h) and of ticks after 24, 48, 72 and 96 h of feeding. There were 22,802,784, 22,275,013, 26,629,453, 24,982,389, and 22,596,230 high-quality clean reads obtained from salivary glands tissues at the five different blood feeding time points. The total number of annotated unigenes was 100,347. The differences in gene expression between different time points were compared, and functional enrichment was performed. Quantitative reverse transcription PCR (RT‒qPCR) was used to validate the RNA-seq results, the results of which showed that the differences in expressed transcripts presented similar trends. Among the identified DEGs, the most numerous were those with catalytic and binding activities and those involved in diverse metabolic pathways and cellular processes. The expression patterns of homologous and family-member proteins throughout the blood feeding period exhibited significant differences, strongly suggesting that the transcriptome composition is highly dynamic and likely subjected to important variation throughout the life cycle. Studies of gene sequences in D. nuttalli will greatly increase the information on tick protective antigens, which could potentially function as effective vaccine candidates or drug targets for the development of environmentally friendly acaricides.
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Guerrib F, Ning C, Mateos-Hernandéz L, Rakotobe S, Park Y, Hajdusek O, Perner J, Vancová M, Valdés JJ, Šimo L. Dual SIFamide receptors in Ixodes salivary glands. INSECT BIOCHEMISTRY AND MOLECULAR BIOLOGY 2023:103963. [PMID: 37257628 DOI: 10.1016/j.ibmb.2023.103963] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/08/2022] [Revised: 05/05/2023] [Accepted: 05/13/2023] [Indexed: 06/02/2023]
Abstract
Salivary glands are vital to tick feeding success and also play a crucial role in tick-borne pathogen transmission. In previous studies of Ixodes scapularis salivary glands, we demonstrated that saliva-producing type II and III acini are innervated by neuropeptidergic axons which release different classes of neuropeptides via their terminals (Šimo et al., 2009b, 2013). Among these, the neuropeptide SIFamide-along with its cognate receptor-were postulated to control the basally located acinar valve via basal epithelial and myoepithelial cells (Vancová et al., 2019). Here, we functionally characterized a second SIFamide receptor (SIFa_R2) from the I. scapularis genome and proved that it senses a low nanomolar level of its corresponding ligand. Insect SIFamide paralogs, SMYamides, also activated the receptor but less effectively compared to SIFamide. Bioinformatic and molecular dynamic analyses suggested that I. scapularis SIFamide receptors are class A GPCRs where the peptide amidated carboxy-terminus is oriented within the receptor binding cavity. The receptor was found to be expressed in Ixodes ricinus salivary glands, synganglia, midguts, trachea, and ovaries, but not in Malpighian tubules. Investigation of the temporal expression patterns suggests that the receptor transcript is highly expressed in unfed I. ricinus female salivary glands and then decreases during feeding. In synganglia, a significant transcript increase was detected in replete ticks. In salivary gland acini, an antibody targeting the second SIFamide receptor recognized basal epithelial cells, myoepithelial cells, and basal granular cells in close proximity to the SIFamide-releasing axon terminals. Immunoreactivity was also detected in specific neurons distributed throughout various I. ricinus synganglion locations. The current findings, alongside previous reports from our group, indicate that the neuropeptide SIFamide acts via two different receptors that regulate distinct or common cell types in the basal region of type II and III acini in I. ricinus salivary glands. The current study investigates the peptidergic regulation of the I. ricinus salivary gland in detail, emphasizing the complexity of this system.
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Affiliation(s)
- Fetta Guerrib
- ANSES, INRAE, Ecole Nationale Vétérinaire d'Alfort, UMR BIPAR, Laboratoire de Santé Animale, 94700, Maisons-Alfort, France
| | - Caina Ning
- ANSES, INRAE, Ecole Nationale Vétérinaire d'Alfort, UMR BIPAR, Laboratoire de Santé Animale, 94700, Maisons-Alfort, France
| | - Lourdes Mateos-Hernandéz
- ANSES, INRAE, Ecole Nationale Vétérinaire d'Alfort, UMR BIPAR, Laboratoire de Santé Animale, 94700, Maisons-Alfort, France
| | - Sabine Rakotobe
- ANSES, INRAE, Ecole Nationale Vétérinaire d'Alfort, UMR BIPAR, Laboratoire de Santé Animale, 94700, Maisons-Alfort, France
| | - Yoonseong Park
- Entomolgy department, Kansas State University, 123 Waters Hall, 66506-4004, Manhattan, KS, USA
| | - Ondrej Hajdusek
- Institute of Parasitology, Biology Centre, Czech Academy of Sciences, Branišovská 31, 37005, České Budějovice, Czech Republic
| | - Jan Perner
- Institute of Parasitology, Biology Centre, Czech Academy of Sciences, Branišovská 31, 37005, České Budějovice, Czech Republic
| | - Marie Vancová
- Institute of Parasitology, Biology Centre, Czech Academy of Sciences, Branišovská 31, 37005, České Budějovice, Czech Republic; Faculty of Science, University of South Bohemia, České Budějovice, 37005, Czech Republic
| | - James J Valdés
- Institute of Parasitology, Biology Centre, Czech Academy of Sciences, Branišovská 31, 37005, České Budějovice, Czech Republic
| | - Ladislav Šimo
- ANSES, INRAE, Ecole Nationale Vétérinaire d'Alfort, UMR BIPAR, Laboratoire de Santé Animale, 94700, Maisons-Alfort, France.
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Trentelman JJA, de Vogel FA, Colstrup E, Sima R, Coumou J, Koetsveld J, Klouwens MJ, Nayak A, Ersoz J, Barriales D, Tomás-Cortázar J, Narasimhan S, Hajdusek O, Anguita J, Hovius JW. Identification of novel conserved Ixodes vaccine candidates; a promising role for non-secreted salivary gland proteins. Vaccine 2022; 40:7593-7603. [PMID: 36357287 DOI: 10.1016/j.vaccine.2022.10.032] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/10/2022] [Revised: 10/09/2022] [Accepted: 10/13/2022] [Indexed: 11/10/2022]
Abstract
Ixodes ricinus and Ixodes scapularis are the main vectors for the causative agents of Lyme borreliosis and a wide range of other pathogens. Repeated tick-bites are known to lead to tick rejection; a phenomenon designated as tick immunity. Tick immunity is mainly directed against tick salivary gland proteins (TSGPs) and has been shown to partially protect against experimental Lyme borreliosis. TSGPs recognized by antibodies from tick immune animals could therefore be interesting candidates for an anti-tick vaccine, which might also block pathogen transmission. To identify conserved Ixodes TSGPs that could serve as a universal anti-tick vaccine in both Europe and the US, a Yeast Surface Display containing salivary gland genes of nymphal I. ricinus expressed at 24, 48 and 72 h into tick feeding was probed with either sera from rabbits repeatedly exposed for 24 h to I. ricinus nymphal ticks and/or sera from rabbits immune to I. scapularis. Thus, we identified thirteen TSGP vaccine candidates, of which ten were secreted. For vaccination studies in rabbits, we selected six secreted TSGPs, five full length and one conserved peptide. None of these proteins hampered tick feeding. In contrast, vaccination of guinea pigs with four non-secreted TSGPs - two from the current and two from a previous human immunoscreening - did significantly reduce tick attachment and feeding. Therefore, non-secreted TSGPs appear to be involved in the development of tick immunity and are interesting candidates for an anti-tick vaccine.
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Affiliation(s)
- Jos J A Trentelman
- Center for Experimental and Molecular Medicine, Amsterdam Infection and Immunity, Amsterdam UMC, Location Academic Medical Center, University of Amsterdam, Amsterdam, the Netherlands.
| | - Fons A de Vogel
- Center for Experimental and Molecular Medicine, Amsterdam Infection and Immunity, Amsterdam UMC, Location Academic Medical Center, University of Amsterdam, Amsterdam, the Netherlands
| | - Emil Colstrup
- Center for Experimental and Molecular Medicine, Amsterdam Infection and Immunity, Amsterdam UMC, Location Academic Medical Center, University of Amsterdam, Amsterdam, the Netherlands
| | - Radek Sima
- Biology Centre, Institute of Parasitology, Czech Academy of Sciences, Ceske Budejovice, Czech Republic; Biopticka laborator s.r.o., Plzen, Czech Republic
| | - Jeroen Coumou
- Center for Experimental and Molecular Medicine, Amsterdam Infection and Immunity, Amsterdam UMC, Location Academic Medical Center, University of Amsterdam, Amsterdam, the Netherlands
| | - Joris Koetsveld
- Center for Experimental and Molecular Medicine, Amsterdam Infection and Immunity, Amsterdam UMC, Location Academic Medical Center, University of Amsterdam, Amsterdam, the Netherlands
| | - Michelle J Klouwens
- Center for Experimental and Molecular Medicine, Amsterdam Infection and Immunity, Amsterdam UMC, Location Academic Medical Center, University of Amsterdam, Amsterdam, the Netherlands
| | - Abhijeet Nayak
- Center for Experimental and Molecular Medicine, Amsterdam Infection and Immunity, Amsterdam UMC, Location Academic Medical Center, University of Amsterdam, Amsterdam, the Netherlands
| | - Jasmin Ersoz
- Center for Experimental and Molecular Medicine, Amsterdam Infection and Immunity, Amsterdam UMC, Location Academic Medical Center, University of Amsterdam, Amsterdam, the Netherlands
| | - Diego Barriales
- CIC bioGUNE-Basque Research & Technology Alliance, Derio 48160, Spain
| | - Julen Tomás-Cortázar
- CIC bioGUNE-Basque Research & Technology Alliance, Derio 48160, Spain; UCD Conway Institute, University College Dublin, Belfield, Dublin 4, Ireland
| | - Sukanya Narasimhan
- Section of Infectious Diseases, Department of Internal Medicine, Yale University, New Haven, CT, USA
| | - Ondrej Hajdusek
- Biology Centre, Institute of Parasitology, Czech Academy of Sciences, Ceske Budejovice, Czech Republic
| | - Juan Anguita
- CIC bioGUNE-Basque Research & Technology Alliance, Derio 48160, Spain; Ikerbasque, Basque Foundation for Science, Bilbao 48012, Spain
| | - Joppe W Hovius
- Center for Experimental and Molecular Medicine, Amsterdam Infection and Immunity, Amsterdam UMC, Location Academic Medical Center, University of Amsterdam, Amsterdam, the Netherlands
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Schäfer M, Pfaff F, Höper D, Silaghi C. Early Transcriptional Changes in the Midgut of Ornithodoros moubata after Feeding and Infection with Borrelia duttonii. Microorganisms 2022; 10:microorganisms10030525. [PMID: 35336101 PMCID: PMC8948914 DOI: 10.3390/microorganisms10030525] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/17/2022] [Accepted: 02/22/2022] [Indexed: 12/16/2022] Open
Abstract
Studies on tick-pathogen-host interactions are helping to identify candidates for vaccines against ticks and tick-borne diseases and to discover potent bioactive tick molecules. The tick midgut is the main tissue involved in blood feeding and, moreover, the first organ to have contact with pathogens ingested through the blood meal. As little is known about the molecular biology of feeding and tick defence mechanisms against microorganisms, but important for understanding vector-pathogen interactions, we explored the early transcriptional changes in the midgut of Ornithodoros moubata after feeding and in response to challenge with the relapsing-fever spirochete Borrelia duttonii using the Ion S5XL platform. Besides transcripts with metabolic function and immune-related transcripts we discovered numerous putative and uncharacterized protein sequences. Overall, our analyses support previous studies and provides a valuable reference database for further functional proteomic analysis of midgut proteins of O. moubata.
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Affiliation(s)
- Mandy Schäfer
- Institute of Infectology, Friedrich-Loeffler-Institut, 17493 Greifswald-Insel Riems, Germany;
- Correspondence:
| | - Florian Pfaff
- Institute of Diagnostic Virology, Friedrich-Loeffler-Institut, 17493 Greifswald-Insel Riems, Germany; (F.P.); (D.H.)
| | - Dirk Höper
- Institute of Diagnostic Virology, Friedrich-Loeffler-Institut, 17493 Greifswald-Insel Riems, Germany; (F.P.); (D.H.)
| | - Cornelia Silaghi
- Institute of Infectology, Friedrich-Loeffler-Institut, 17493 Greifswald-Insel Riems, Germany;
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Perner J, Kucera M, Frantova H, Urbanova V, Kopacek P, Sima R. Lyme disease transmission by severely impaired ticks. Open Biol 2022; 12:210244. [PMID: 35167765 PMCID: PMC8846998 DOI: 10.1098/rsob.210244] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/09/2023] Open
Abstract
It has been demonstrated that impairing protein synthesis using drugs targeted against tRNA amino acid synthetases presents a promising strategy for the treatment of a wide variety of parasitic diseases, including malaria and toxoplasmosis. This is the first study evaluating tRNA synthetases as potential drug targets in ticks. RNAi knock-down of all tested tRNA synthetases had a strong deleterious phenotype on Ixodes ricinus feeding. Our data indicate that tRNA synthetases represent attractive, anti-tick targets warranting the design of selective inhibitors. Further, we tested whether these severely impaired ticks were capable of transmitting Borrelia afzelii spirochaetes. Interestingly, biologically handicapped I. ricinus nymphs transmitted B. afzelii in a manner quantitatively sufficient to develop a systemic infection in mice. These data suggest that initial blood-feeding, despite the incapability of ticks to fully feed and salivate, is sufficient for activating B. afzelii from a dormant to an infectious mode, enabling transmission and dissemination in host tissues.
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Affiliation(s)
- Jan Perner
- Institute of Parasitology, Biology Centre of the Czech Academy of Sciences, Ceske Budejovice 37005, Czech Republic
| | - Matej Kucera
- Institute of Parasitology, Biology Centre of the Czech Academy of Sciences, Ceske Budejovice 37005, Czech Republic
| | - Helena Frantova
- Institute of Parasitology, Biology Centre of the Czech Academy of Sciences, Ceske Budejovice 37005, Czech Republic
| | - Veronika Urbanova
- Institute of Parasitology, Biology Centre of the Czech Academy of Sciences, Ceske Budejovice 37005, Czech Republic
| | - Petr Kopacek
- Institute of Parasitology, Biology Centre of the Czech Academy of Sciences, Ceske Budejovice 37005, Czech Republic
| | - Radek Sima
- Institute of Parasitology, Biology Centre of the Czech Academy of Sciences, Ceske Budejovice 37005, Czech Republic
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Ferreira Leal B, Sanchez Ferreira CA. Ticks and antibodies: May parasite density and tick evasion influence the outcomes following immunization protocols? Vet Parasitol 2021; 300:109610. [PMID: 34735848 DOI: 10.1016/j.vetpar.2021.109610] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/03/2021] [Revised: 09/07/2021] [Accepted: 10/19/2021] [Indexed: 11/30/2022]
Abstract
Ticks are a major concern to human health and livestock worldwide, being responsible for economic losses that go beyond billions of US dollars per year. This scenario instigates the development of vaccines against these ectoparasites, emphasized by the fact that the main method of controlling ticks still relies on the use of acaricides, what increases costs and may affect the environment as well as human and animal health. The first commercial vaccines against ectoparasites were produced against the tick Rhipicephalus microplus and their efficacy were based on antibodies. Many additional attempts have been conducted to produce protective immune responses against ticks by immunization with specific antigens and the antibody response has usually been the main target of evaluation. But some controversy still populates the roles possibly performed by humoral responses in tick-mammalian host relationships. This review focuses on the analysis of specific aspects concerning antibodies and ticks, especially the influence of parasite density and evasion/modulation. The immunization trials already described against R. microplus were also compiled and analyzed based on the characteristics of the molecules tested, protocols of immunization and tick challenge. Within these issues, it is discussed if or when antibody levels can be directly correlated with the development of tick resistance, and whether anti-tick protective immune responses generated by infestations may become ineffective under a different tick density. Also, higher titers of antibodies can be correlated with protection or susceptibility to tick infestations, what may be altered following continuous or repeated infestations and differ greatly comparing hosts with distinct genetic backgrounds. Regarding evasion, ticks present a sophisticated mechanism for dealing with antibodies, including Immunoglobulin Binding Proteins (IGBPs), that capture, transport and inject them back into the host, while keeping their properties within the parasite. The comparison of immunization protocols shows a total of 22 molecules already tested in cattle vaccination trials against R. microplus, with the predominance of concealed and dual antigens as well as marked differences in tick challenge schemes. The presence of an antibody evasion apparatus and variable levels of tick resistance when facing different densities of parasites are concerns that should be considered when testing vaccine candidates. Ultimately, more refinement may be necessary to effectively design a cocktail vaccine with tick molecules, which may be needed to be altered and combined in non-competing immune contexts to be universally secure and protective.
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Affiliation(s)
- Bruna Ferreira Leal
- Laboratório de Imunologia e Microbiologia, Pontifícia Universidade Católica do Rio Grande do Sul (PUCRS), Av. Ipiranga, 6681, 90619-900, Porto Alegre, RS, Brazil.
| | - Carlos Alexandre Sanchez Ferreira
- Laboratório de Imunologia e Microbiologia, Pontifícia Universidade Católica do Rio Grande do Sul (PUCRS), Av. Ipiranga, 6681, 90619-900, Porto Alegre, RS, Brazil.
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