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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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Tjale MA, Liebenberg J, Steyn H, Van Kleef M, Pretorius A. Transcriptome analysis of Ehrlichia ruminantium in the ruminant host at the tick bite site and in the tick vector salivary glands. Ticks Tick Borne Dis 2020; 12:101646. [PMID: 33508537 DOI: 10.1016/j.ttbdis.2020.101646] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/12/2020] [Revised: 12/18/2020] [Accepted: 12/19/2020] [Indexed: 10/22/2022]
Abstract
Heartwater is a non-contagious tick-borne disease of domestic and wild ruminants. Data regarding the complex processes involved during pathogen-vector-host interaction during Ehrlichia ruminantium infection is lacking and could be improved with knowledge associated with gene expression changes in both the pathogen and the host. Thus, in the current study, we aimed to identify E. ruminantium genes that are up-regulated when the pathogen enters the host and before the disease is established. Identification of such genes/proteins may aid in future vaccine development strategies against heartwater. RNA-sequencing was used to identify E. ruminantium genes that were exclusively expressed at the tick bite site in sheep skin biopsies (SB) and in adult tick salivary glands (SG). RNA was extracted from pooled samples of the SB or SG collected at different time points during tick attachment and prior to disease manifestation. Ribosomal RNA (rRNA) was removed and the samples were sequenced. Several E. ruminantium genes were highly expressed in all the samples while others were exclusively expressed in each. It was concluded that E. ruminantium genes that were exclusively expressed in the SB or both SB and SG when compared to the transcriptome datasets from bovine elementary bodies (BovEBs) from cell culture may be considered as early antigenic targets of host immunity. In silico immunogenic epitope prediction analysis and preliminary characterization of selected genes in vitro using ELIspot assay showed that they could possibly be ideal targets for future vaccine development against heartwater, however, further epitope characterization is still required.
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Affiliation(s)
- Mabotse A Tjale
- Department of Veterinary Tropical Disease, Faculty of Veterinary Science, University of Pretoria, Private Bag X04, Onderstepoort 0110, South Africa; Agricultural Research Council - Onderstepoort Veterinary Research, Private Bag X5, Onderstepoort 0110, South Africa.
| | - Junita Liebenberg
- Agricultural Research Council - Onderstepoort Veterinary Research, Private Bag X5, Onderstepoort 0110, South Africa
| | - Helena Steyn
- Agricultural Research Council - Onderstepoort Veterinary Research, Private Bag X5, Onderstepoort 0110, South Africa
| | - Mirinda Van Kleef
- Department of Veterinary Tropical Disease, Faculty of Veterinary Science, University of Pretoria, Private Bag X04, Onderstepoort 0110, South Africa; Agricultural Research Council - Onderstepoort Veterinary Research, Private Bag X5, Onderstepoort 0110, South Africa
| | - Alri Pretorius
- Department of Veterinary Tropical Disease, Faculty of Veterinary Science, University of Pretoria, Private Bag X04, Onderstepoort 0110, South Africa; Agricultural Research Council - Onderstepoort Veterinary Research, Private Bag X5, Onderstepoort 0110, South Africa
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A multi-epitope DNA vaccine co-administered with monophosphoryl lipid A adjuvant provides protection against tick transmitted Ehrlichia ruminantium in sheep. Vaccine 2019; 37:4354-4363. [PMID: 31248684 DOI: 10.1016/j.vaccine.2019.06.027] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/22/2019] [Revised: 06/10/2019] [Accepted: 06/11/2019] [Indexed: 01/25/2023]
Abstract
Previously, a heartwater experimental DNA vaccine provided 100% protection following laboratory challenge with Ehrlichia ruminantium administered by needle but not against an E. ruminantium tick challenge in the field. A multi-epitope DNA vaccine incorporating both CD4+ and CD8+ cytotoxic T lymphocytes epitopes could provide a better alternative. In this study, we investigated the use of multi-epitope DNA vaccines against an E. ruminantium experimental tick challenge in sheep. The multi-epitope DNA vaccines were delivered via the intramuscular route and intradermal route using the gene gun in the presence of monophosphoryl lipid A (MPL) adjuvant, which was either applied topically to the gene gun inoculation site or co-administered with the vaccine via the intramuscular route. Initially two constructs namely, pSignal plus and pLamp were tested with MPL applied topically only and no protection was obtained in this formulation. However, when pLamp was co-administered with MPL via the intramuscular route in addition to topical application, its protective efficiency improved to protect 60% of the sheep against tick challenge. In this formulation, the vaccine induced enhanced activation of memory T cell responses both before and after challenge with variations amongst the different sheep possibly due to their different genetic backgrounds. In conclusion, this study showed that a heartwater multi-epitope DNA vaccine, co-administered with MPL adjuvant can protect sheep following a laboratory E. ruminantium tick challenge.
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Thema N, Tshilwane S, Pretorius A, Son L, Smith R, Steyn H, Liebenberg J, van Kleef M. Identification and characterisation of conserved epitopes of E. ruminantium that activate Th1 CD4+ T cells: Towards the development of a multi-epitope vaccine. Mol Immunol 2019; 107:106-114. [DOI: 10.1016/j.molimm.2018.12.012] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/19/2018] [Revised: 11/06/2018] [Accepted: 12/09/2018] [Indexed: 01/21/2023]
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Thema N, Tshilwane S, Son L, Smith R, Faber F, Steyn H, van Kleef M, Liebenberg J, Pretorius A. Ehrlichia ruminantium antigens and peptides induce cytotoxic T cell responses in vitro. Vet Immunol Immunopathol 2019; 207:1-9. [DOI: 10.1016/j.vetimm.2018.11.012] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/19/2018] [Revised: 10/25/2018] [Accepted: 11/18/2018] [Indexed: 01/31/2023]
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Nefefe T, Liebenberg J, van Kleef M, Steyn HC, Pretorius A. Innate immune transcriptomic evaluation of PBMC isolated from sheep after infection with E. ruminantium Welgevonden strain. Mol Immunol 2017; 91:238-248. [PMID: 28988038 DOI: 10.1016/j.molimm.2017.09.018] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/27/2017] [Revised: 08/18/2017] [Accepted: 09/27/2017] [Indexed: 12/30/2022]
Abstract
Heartwater is a tick-borne non-infectious fatal disease of wild and domestic ruminants caused by the bacterium Ehrlichia ruminantium, transmitted by Amblyomma ticks. Although there is evidence that interferon-gamma (IFN-γ) controls E. ruminantium growth and that cellular immune responses could be protective, an effective recombinant vaccine for this disease is lacking. An overall analysis of which immune pathways are up- or down-regulated in sheep peripheral blood mononuclear cells is expected to lead to a better understanding of the global immune response of sheep to E. ruminantium infection. Therefore, a systems biology oriented approach following the infection with E. ruminantium was investigated from peripheral blood mononuclear cells to aid recombinant vaccine development. In this study, heartwater naïve sheep were infected and challenged by allowing E. ruminantium infected ticks to feed on them. After primary infection, all the animals were treated with antibiotic during the resulting febrile response. Blood was collected daily for E. ruminantium detection by qPCR (pCS20 assay). The pCS20 assay only detected the pathogen in the blood one day prior to and during the febrile stage of infection confirming infection of the sheep. IFN-γ real-time PCR indicated that this cytokine was expressed at specific time points: post infection, during the febrile stage of the disease and after challenge. These were used as a guide to select samples for transcriptome sequencing. This paper focuses on transcripts that are associated with innate activating pathways that were identified to be up- and down-regulated after primary infection and the subsequent challenge. These included the CD14 monocyte marker, toll-like receptor (TLR), nod-like receptor, chemokine, cytosolic and cytokine-cytokine interaction receptor pathways. In particular, TLR4, TLR9 and CD14 were activated together with DNA detection pathways, suggesting that vaccine formulations may be improved if CpG motifs and lipopolysaccharides are included. This data indicates that innate immune activation, perhaps by using adjuvants, should be an important component for consideration during future heartwater recombinant vaccine development.
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Affiliation(s)
- T Nefefe
- Agricultural Research Council - Onderstepoort Veterinary Research, Private Bag X5, Onderstepoort, 0110, South Africa; Department of Veterinary Tropical Diseases, University of Pretoria, Private Bag X04, Onderstepoort, 0110, South Africa.
| | - J Liebenberg
- Agricultural Research Council - Onderstepoort Veterinary Research, Private Bag X5, Onderstepoort, 0110, South Africa
| | - M van Kleef
- Agricultural Research Council - Onderstepoort Veterinary Research, Private Bag X5, Onderstepoort, 0110, South Africa; Department of Veterinary Tropical Diseases, University of Pretoria, Private Bag X04, Onderstepoort, 0110, South Africa
| | - H C Steyn
- Agricultural Research Council - Onderstepoort Veterinary Research, Private Bag X5, Onderstepoort, 0110, South Africa
| | - A Pretorius
- Agricultural Research Council - Onderstepoort Veterinary Research, Private Bag X5, Onderstepoort, 0110, South Africa; Department of Veterinary Tropical Diseases, University of Pretoria, Private Bag X04, Onderstepoort, 0110, South Africa
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Tjale MA, Pretorius A, Josemans A, Kleef MV, Liebenberg J. Transcriptomic analysis of Ehrlichia ruminantium during the developmental stages in bovine and tick cell culture. Ticks Tick Borne Dis 2017; 9:126-134. [PMID: 29017825 DOI: 10.1016/j.ttbdis.2017.09.014] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/05/2017] [Revised: 09/15/2017] [Accepted: 09/18/2017] [Indexed: 01/06/2023]
Abstract
The use of bioinformatics tools to search for possible vaccine candidates has been successful in recent years. In an attempt to search for additional vaccine candidates or improve the current heartwater vaccine design, a genome-wide transcriptional profile of E. ruminantium (Welgevonden strain) replicating in bovine endothelial cells (BA886) and Ixodes scapularis embryonic tick cells (IDE8) was performed. The RNA was collected from the infective extracellular form, the elementary bodies (EBs) and vegetative intracellular form, reticulate bodies (RBs) and was used for transcriptome sequencing. Several genes previously implicated with adhesion, attachment and pathogenicity were exclusively up-regulated in the EBs from bovine and tick cells. Similarly, genes involved in adaptation or survival of E. ruminantium in the host cells were up-regulated in the RBs from bovine cells. Thus, it was concluded that those genes expressed in the EBs might be important for infection of mammalian and tick host cells and these may be targets for both cell and humoral mediated immune responses. Alternatively, those exclusively expressed in the RBs may be important for survival in the host cells. Exported or secreted proteins exclusively expressed at this stage are ideal targets for the stimulation of cytotoxic T-lymphocyte (CTL) immune responses in the host.
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Affiliation(s)
- Mabotse A Tjale
- Agricultural Research Council - Onderstepoort Veterinary Research, Private Bag X5, Onderstepoort 0110, South Africa; Department of Veterinary Tropical Diseases, Faculty of Veterinary Science, University of Pretoria, Private Bag X04, Onderstepoort 0110, South Africa.
| | - Alri Pretorius
- Agricultural Research Council - Onderstepoort Veterinary Research, Private Bag X5, Onderstepoort 0110, South Africa; Department of Veterinary Tropical Diseases, Faculty of Veterinary Science, University of Pretoria, Private Bag X04, Onderstepoort 0110, South Africa
| | - Antoinette Josemans
- Agricultural Research Council - Onderstepoort Veterinary Research, Private Bag X5, Onderstepoort 0110, South Africa
| | - Mirinda Van Kleef
- Agricultural Research Council - Onderstepoort Veterinary Research, Private Bag X5, Onderstepoort 0110, South Africa; Department of Veterinary Tropical Diseases, Faculty of Veterinary Science, University of Pretoria, Private Bag X04, Onderstepoort 0110, South Africa
| | - Junita Liebenberg
- Agricultural Research Council - Onderstepoort Veterinary Research, Private Bag X5, Onderstepoort 0110, South Africa.
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