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Pretorius A, Nefefe T, Thema N, Liebenberg J, Steyn H, van Kleef M. Screening for immune biomarkers associated with infection or protection against Ehrlichia ruminantium by RNA-sequencing analysis. Microb Pathog 2024; 189:106588. [PMID: 38369169 DOI: 10.1016/j.micpath.2024.106588] [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: 11/02/2023] [Revised: 01/11/2024] [Accepted: 02/15/2024] [Indexed: 02/20/2024]
Abstract
Heartwater is one of the most economically important tick-borne fatal diseases of livestock. The disease is caused by the bacteria Ehrlichia ruminantium transmitted by Amblyomma ticks. Although there is evidence that interferon-gamma controls E. ruminantium growth and that cellular immune responses are protective, an effective recombinant vaccine for this disease is lacking. Analyses of markers associated with infection as well as protection will lead to a better understanding of the E. ruminantium immune response and corresponding pathways induced in sheep peripheral blood mononuclear cells (PBMC) will assist in development of such a vaccine. In this study, Biomarkers of infection (BMI) were identified as uniquely expressed genes during primary infection and biomarkers of protection (BMP) associated with immune to heartwater were identified post challenge. Sheep were experimentally infected and challenged with E. ruminantium infected ticks. The immune phenotypic and transcriptome profile of their PBMC were compared to their own naïve PBMC collected before infection. The study revealed 305 differentially expressed genes (DEGs) as BMI, of these 17 were upregulated at all three time-points investigated. These DEGs, form part of the bacterial invasion of epithelial cells Kyoto Encyclopaedia of Genes and Genomes (KEGG) pathway, and others detected from day 1 post infection and are considered predictive markers for early heartwater infection in ruminants. Similarly, a total of 332 DEGs were identified as BMP, of these 100 were upregulated and 75 were downregulated at all three time-points investigated. However, at D1PC most DEGs were downregulated (n = 1312) that correlated with a reduction in the % CD4 and CD8 T cells detected with flow cytometry. KEGG pathway analyses showed complete down regulation of T cell specific pathways possibly due to homing of immune cells to the site of infection after acquired immunity developed. At D4PC, expression levels of most of these downregulated genes increased and by D6PC they were upregulated. This indicates that the sampling time-point for biomarker analyses is important when results for acquired immune responses are inferred. This data identified DEGs that could be considered as biomarkers of protective immunity that can be used for identification of vaccine antigens and provides a strong foundation to further development of heartwater recombinant vaccines.
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Affiliation(s)
- A Pretorius
- Agricultural Research Council -Onderstepoort Veterinary Research, Private Bag X05, Onderstepoort, 0110, South Africa; Department of Veterinary Tropical Diseases, University of Pretoria, Private Bag X04, Onderstepoort, 0110, South Africa.
| | - T Nefefe
- Agricultural Research Council -Onderstepoort Veterinary Research, Private Bag X05, Onderstepoort, 0110, South Africa; Department of Veterinary Tropical Diseases, University of Pretoria, Private Bag X04, Onderstepoort, 0110, South Africa
| | - N Thema
- Agricultural Research Council -Onderstepoort Veterinary Research, Private Bag X05, Onderstepoort, 0110, South Africa
| | - J Liebenberg
- Agricultural Research Council -Onderstepoort Veterinary Research, Private Bag X05, Onderstepoort, 0110, South Africa
| | - H Steyn
- Agricultural Research Council -Onderstepoort Veterinary Research, Private Bag X05, Onderstepoort, 0110, South Africa
| | - M van Kleef
- Agricultural Research Council -Onderstepoort Veterinary Research, Private Bag X05, Onderstepoort, 0110, South Africa; Department of Veterinary Tropical Diseases, University of Pretoria, Private Bag X04, Onderstepoort, 0110, South Africa
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Abbas MN, Jmel MA, Mekki I, Dijkgraaf I, Kotsyfakis M. Recent Advances in Tick Antigen Discovery and Anti-Tick Vaccine Development. Int J Mol Sci 2023; 24:ijms24054969. [PMID: 36902400 PMCID: PMC10003026 DOI: 10.3390/ijms24054969] [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: 12/31/2022] [Revised: 02/28/2023] [Accepted: 03/01/2023] [Indexed: 03/08/2023] Open
Abstract
Ticks can seriously affect human and animal health around the globe, causing significant economic losses each year. Chemical acaricides are widely used to control ticks, which negatively impact the environment and result in the emergence of acaricide-resistant tick populations. A vaccine is considered as one of the best alternative approaches to control ticks and tick-borne diseases, as it is less expensive and more effective than chemical controls. Many antigen-based vaccines have been developed as a result of current advances in transcriptomics, genomics, and proteomic techniques. A few of these (e.g., Gavac® and TickGARD®) are commercially available and are commonly used in different countries. Furthermore, a significant number of novel antigens are being investigated with the perspective of developing new anti-tick vaccines. However, more research is required to develop new and more efficient antigen-based vaccines, including on assessing the efficiency of various epitopes against different tick species to confirm their cross-reactivity and their high immunogenicity. In this review, we discuss the recent advancements in the development of antigen-based vaccines (traditional and RNA-based) and provide a brief overview of recent discoveries of novel antigens, along with their sources, characteristics, and the methods used to test their efficiency.
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Affiliation(s)
- Muhammad Nadeem Abbas
- State Key Laboratory of Silkworm Genome Biology, Southwest University, Chongqing 400716, China
| | - Mohamed Amine Jmel
- Laboratory of Genomics and Proteomics of Disease Vectors, Institute of Parasitology, Biology Centre, Czech Academy of Sciences, 37005 Ceske Budejovice, Czech Republic
| | - Imen Mekki
- Laboratory of Genomics and Proteomics of Disease Vectors, Institute of Parasitology, Biology Centre, Czech Academy of Sciences, 37005 Ceske Budejovice, Czech Republic
| | - Ingrid Dijkgraaf
- Department of Biochemistry, CARIM, Maastricht University, 6229 ER Maastricht, The Netherlands
| | - Michail Kotsyfakis
- Laboratory of Genomics and Proteomics of Disease Vectors, Institute of Parasitology, Biology Centre, Czech Academy of Sciences, 37005 Ceske Budejovice, Czech Republic
- Correspondence:
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Ngoepe TA, Pretorius A, Steyn HC, Van Kleef M. Th1 and Th2 epitopes of Cowdria polymorphic gene 1 of Ehrlichia ruminantium. Onderstepoort J Vet Res 2023; 90:e1-e15. [PMID: 37042556 PMCID: PMC10091069 DOI: 10.4102/ojvr.v90i1.2070] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/02/2022] [Revised: 11/03/2022] [Accepted: 11/17/2022] [Indexed: 02/05/2023] Open
Abstract
Cowdria polymorphic gene 1 (cpg1, Erum2510, ERUM_RS01380) has been shown to induce 30% and 100% protection in sheep immunised by deoxyribonucleic acid (DNA) prime combined with DNA boost and DNA prime combined with protein boost, respectively, against heartwater infection via needle challenge. To localise its antigenic regions for inclusion in a multi-epitope DNA vaccine against heartwater, Erum2510 was cleaved into five overlapping subfragments. These subfragments were expressed individually in an Escherichia coli host expression system and evaluated for their ability to induce proliferative responses, Th1 and Th2 cytokines (interferon gamma [IFN-γ] and interleukin 4 [IL-4]) via enzyme-linked immunospot (ELISpot), quantitative real time polymerase chain reaction (qRT-PCR) and flow cytometry. Recombinant (r)proteins 3 and 4 were shown to induce immunodominant Th1 and Th2 immune responses characterised by the secretion of effector cytokines IFN-γ and IL-4 in addition to differential messenger ribonucleic acid (mRNA) expression of tumour necrosis factor (TNF), IL-2, IL-1, IL-18, IL-10, transforming growth factor (TGF), granulocyte-macrophage colony-stimulating factor (GM-CSF) and inducible nitric oxide synthase (iNOS). Thirty-seven overlapping synthetic peptides (16 mer) spanning the lengths of these immunodominant rproteins were synthesised and assayed. A peptide pool comprising p9 and p10 derived from rprotein 3 induced a Th1-biased immune response. A peptide pool comprising p28 and p29 derived from rprotein 4 induced a mixed Th1 and Th2 immune response characterised by secretion of IFN-γ and differential mRNA expression of IL-1, IL-2, IL-10, IL-12, iNOS, TGF, TNF and GM-CSF. Only one of the peptides (p29) induced secretion of IL-4. Phenotypic analysis showed significant activation of cluster of differentiation 8+ (CD8+), cluster of differentiation 4+ (CD4+) and B+ lymphocyte populations. Findings suggest that Erum2510 rproteins and synthetic peptides can induce both cellular and humoral immune responses, thereby implicating their importance in protection against heartwater.Contribution: This study will facilitate the design of an effective multi-epitope DNA vaccine against heartwater that will contribute to control this economically important disease in sub-Saharan Africa and beyond.
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Affiliation(s)
- Tlou A Ngoepe
- Department of Immunology, Agricultural Research Council-Onderstepoort Veterinary Research, Pretoria, South Africa; and, Department of Veterinary Tropical Diseases, Faculty of Veterinary Science, University of Pretoria, Pretoria, South Africa; and, Department of Immunology, Faculty of Health Sciences, University of Pretoria, Pretoria,.
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Latif AA, Steyn HC, Josemans AI, Marumo RD, Pretorius A, Christo Troskie P, Combrink MP, Molepo LC, Haw A, Mbizeni S, Zweygarth E, Mans BJ. Safety and efficacy of an attenuated heartwater (Ehrlichia ruminantium) vaccine administered by the intramuscular route in cattle, sheep and Angora goats. Vaccine 2020; 38:7780-7788. [PMID: 33109388 DOI: 10.1016/j.vaccine.2020.10.032] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/17/2020] [Revised: 10/07/2020] [Accepted: 10/09/2020] [Indexed: 10/23/2022]
Abstract
Heartwater is an economically important tick-borne disease of ruminants in Africa. The current commercial vaccine uses live Ehrlichia ruminantium from blood of infected sheep, requires antibiotic treatment during infection, needs to be administered intravenously and does not protect against all South African isolates. An attenuated tissue culture vaccine not requiring antibiotic treatment and effective against different field strains in small groups of goats and sheep was reported previously. The objective of the present study was to test safety and efficacy of this vaccine administered by intramuscular (i.m.) inoculation in larger groups of sheep, Angora goats and cattle. Animals were vaccinated via intravenous (i.v.) and i.m. routes and received E. ruminantium homologous challenge by feeding of infected ticks or by i.v. inoculation of infected blood. For vaccine titration in sheep and goats, the optimum safe and efficacious dose was determined using 2 ml equivalent of 102-105 culture-derived live elementary bodies (EBs). Similarly, the vaccine was titrated in cattle using 5 ml containing 105-107 EBs. Seventy percent of i.v. vaccinated and 9.7% of i.m. vaccinated Angora goats receiving 105 EBs, developed severe reactions to vaccination and were treated. These treated animals and the remaining 90.3% of i.m.- vaccinated goats showed 100% protection against i.v. or tick challenge. Sheep and Angora goats vaccinated i.m. with 104 EBs had no vaccination reactions and were fully protected against i.v. or tick challenge. Similarly, vaccinated cattle (dose 106 EBs) did not react to vaccine inoculation and were fully protected against i.v. or tick homologous challenge. Control non-vaccinated animals reacted severely to challenge and required oxytetracycline treatment. This successfully demonstrated that Angora goats, sheep and cattle can be safely vaccinated with the attenuated E. ruminantium Welgevonden vaccine via the i.m. route, with no clinical reactions to vaccination and 100% protection against virulent i.v. and homologous tick challenge.
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Affiliation(s)
- Abdalla A Latif
- School of Life Sciences, University of KwaZulu-Natal, Durban, Westville, South Africa; Agricultural Research Council-Onderstepoort Veterinary Research, Onderstepoort 0110, South Africa.
| | - Helena C Steyn
- Agricultural Research Council-Onderstepoort Veterinary Research, Onderstepoort 0110, South Africa
| | - Antoinette I Josemans
- Agricultural Research Council-Onderstepoort Veterinary Research, Onderstepoort 0110, South Africa
| | - Ratselane D Marumo
- Agricultural Research Council-Onderstepoort Veterinary Research, Onderstepoort 0110, South Africa
| | - Alri Pretorius
- Agricultural Research Council-Onderstepoort Veterinary Research, Onderstepoort 0110, South Africa; The Department of Veterinary Tropical Diseases, University of Pretoria, Pretoria, South Africa
| | - P Christo Troskie
- Agricultural Research Council-Onderstepoort Veterinary Research, Onderstepoort 0110, South Africa
| | - Michael P Combrink
- Agricultural Research Council-Onderstepoort Veterinary Research, Onderstepoort 0110, South Africa
| | - Lefoka C Molepo
- Agricultural Research Council-Onderstepoort Veterinary Research, Onderstepoort 0110, South Africa
| | - Anna Haw
- Agricultural Research Council-Onderstepoort Veterinary Research, Onderstepoort 0110, South Africa
| | - Sikhumbuzo Mbizeni
- Agricultural Research Council-Onderstepoort Veterinary Research, Onderstepoort 0110, South Africa; Department of Agriculture and Animal Health, College of Agriculture & Environmental Sciences, University of South Africa, South Africa
| | - Erich Zweygarth
- The Department of Veterinary Tropical Diseases, University of Pretoria, Pretoria, South Africa
| | - Ben J Mans
- Agricultural Research Council-Onderstepoort Veterinary Research, Onderstepoort 0110, South Africa; The Department of Veterinary Tropical Diseases, University of Pretoria, Pretoria, South Africa; Department of Life and Consumer Sciences, College of Agriculture & Environmental Sciences, University of South Africa, South Africa
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