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Oboge H, Riitho V, Nyamai M, Omondi GP, Lacasta A, Githaka N, Nene V, Aboge G, Thumbi SM. Safety and efficacy of toll-like receptor agonists as therapeutic agents and vaccine adjuvants for infectious diseases in animals: a systematic review. Front Vet Sci 2024; 11:1428713. [PMID: 39355141 PMCID: PMC11442433 DOI: 10.3389/fvets.2024.1428713] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/06/2024] [Accepted: 08/20/2024] [Indexed: 10/03/2024] Open
Abstract
Introduction Strengthening global health security relies on adequate protection against infectious diseases through vaccination and treatment. Toll-like receptor (TLR) agonists exhibit properties that can enhance immune responses, making them potential therapeutic agents or vaccine adjuvants. Methods We conducted an extensive systematic review to assess the efficacy of TLR agonists as therapeutic agents or vaccine adjuvants for infectious diseases and their safety profile in animals, excluding rodents and cold-blooded animals. We collected qualitative and available quantitative data on the efficacy and safety outcomes of TLR agonists and employed descriptive analysis to summarize the outcomes. Results Among 653 screened studies, 51 met the inclusion criteria. In this review, 82% (42/51) of the studies used TLR agonists as adjuvants, while 18% (9/51) applied TLR agonist as therapeutic agents. The predominant TLR agonists utilized in animals against infectious diseases was CpG ODN, acting as a TLR9 agonist in mammals, and TLR21 agonists in chickens. In 90% (46/51) of the studies, TLR agonists were found effective in stimulating specific and robust humoral and cellular immune responses, thereby enhancing the efficacy of vaccines or therapeutics against infectious diseases in animals. Safety outcomes were assessed in 8% (4/51) of the studies, with one reporting adverse effects. Discussion Although TLR agonists are efficacious in enhancing immune responses and the protective efficacy of vaccines or therapeutic agents against infectious diseases in animals, a thorough evaluation of their safety is imperative to in-form future clinical applications in animal studies. Systematic review registration https://www.crd.york.ac.uk/prospero/display_record.php?RecordID=323122.
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Affiliation(s)
- Harriet Oboge
- Department of Public Health Pharmacology and Toxicology, Faculty of Veterinary Medicine, University of Nairobi, Nairobi, Kenya
- Centre for Epidemiological Modelling and Analysis, University of Nairobi, Nairobi, Kenya
- Paul G. Allen School for Global Health, Washington State University, Pullman, WA, United States
- Animal and Human Health, International Livestock Research Institute, Nairobi, Kenya
- Feed the Future Innovation Lab for Animal Health, Washington State University, Pullman, WA, United States
| | - Victor Riitho
- Centre for Epidemiological Modelling and Analysis, University of Nairobi, Nairobi, Kenya
- Institute of Tropical and Infectious Diseases, University of Nairobi, Nairobi, Kenya
| | - Mutono Nyamai
- Centre for Epidemiological Modelling and Analysis, University of Nairobi, Nairobi, Kenya
- Paul G. Allen School for Global Health, Washington State University, Pullman, WA, United States
- Feed the Future Innovation Lab for Animal Health, Washington State University, Pullman, WA, United States
| | - George P Omondi
- Feed the Future Innovation Lab for Animal Health, Washington State University, Pullman, WA, United States
- Department of Clinical Studies, Faculty of Veterinary Medicine, University of Nairobi, Nairobi, Kenya
| | - Anna Lacasta
- Animal and Human Health, International Livestock Research Institute, Nairobi, Kenya
- Feed the Future Innovation Lab for Animal Health, Washington State University, Pullman, WA, United States
| | - Naftaly Githaka
- Animal and Human Health, International Livestock Research Institute, Nairobi, Kenya
- Feed the Future Innovation Lab for Animal Health, Washington State University, Pullman, WA, United States
| | - Vishvanath Nene
- Animal and Human Health, International Livestock Research Institute, Nairobi, Kenya
- Feed the Future Innovation Lab for Animal Health, Washington State University, Pullman, WA, United States
| | - Gabriel Aboge
- Department of Public Health Pharmacology and Toxicology, Faculty of Veterinary Medicine, University of Nairobi, Nairobi, Kenya
- Institute of Tropical and Infectious Diseases, University of Nairobi, Nairobi, Kenya
| | - S M Thumbi
- Centre for Epidemiological Modelling and Analysis, University of Nairobi, Nairobi, Kenya
- Paul G. Allen School for Global Health, Washington State University, Pullman, WA, United States
- Feed the Future Innovation Lab for Animal Health, Washington State University, Pullman, WA, United States
- Institute of Immunology and Infection Research, School of Biological Sciences, University of Edinburgh, Edinburgh, United Kingdom
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Tawana M, Onyiche TE, Ramatla T, Mtshali S, Thekisoe O. Epidemiology of Ticks and Tick-Borne Pathogens in Domestic Ruminants across Southern African Development Community (SADC) Region from 1980 until 2021: A Systematic Review and Meta-Analysis. Pathogens 2022; 11:pathogens11080929. [PMID: 36015049 PMCID: PMC9414594 DOI: 10.3390/pathogens11080929] [Citation(s) in RCA: 5] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/04/2022] [Revised: 04/14/2022] [Accepted: 04/15/2022] [Indexed: 11/16/2022] Open
Abstract
Ticks are hematophagous ectoparasites that are capable of infesting a wide range of mammals, including domestic animals, ruminants, wildlife, and humans across the world, and they transmit disease-causing pathogens. Numerous individual epidemiological studies have been conducted on the distribution and prevalence of ticks and tick-borne diseases (TBDs) in the Southern African Developing Community (SADC) region, but no effort has been undertaken to synchronize findings, which would be helpful in the implementation of consolidated tick control measures. With the aim of generating consolidated pooled prevalence estimates of ticks and TBDs in the SADC region, we performed a systematic review and meta-analysis of published articles using the PRISMA 2020 guidelines. A deep search was performed on five electronic databases, namely, PubMed, ScienceDirect, Google Scholar, AJOL, and Springer Link. Of the 347 articles identified, only 61 of the articles were eligible for inclusion. In total, 18,355 tick specimens were collected, belonging to the genera Amblyomma, Haemaphysalis, Hyalomma, and Rhipicephalus (including Boophilus) across several countries, including South Africa (n = 8), Tanzania (n = 3), Zambia (n = 2), Zimbabwe (n = 2), Madagascar (n = 2), Angola (n = 2), Mozambique (n = 1), and Comoros (n = 1). The overall pooled prevalence estimate (PPE) of TBPs in livestock was 52.2%, with the highest PPE in cattle [51.2%], followed by sheep [45.4%], and goats [29.9%]. For bacteria-like and rickettsial TBPs, Anaplasma marginale had the highest PPE of 45.9%, followed by A. centrale [14.7%], A. phagocytophilum [2.52%], and A. bovis [0.88%], whilst Ehrlichia ruminantium had a PPE of 4.2%. For piroplasmids, Babesia bigemina and B. bovis had PPEs of 20.8% and 20.3%, respectively. Theileria velifera had the highest PPE of 43.0%, followed by T. mutans [29.1%], T. parva [25.0%], and other Theileria spp. [14.06%]. Findings from this study suggest the need for a consolidated scientific approach in the investigation of ticks, TBPs, and TBDs in the whole SADC region, as most of the TBDs are transboundary and require a regional control strategy.
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Affiliation(s)
- Mpho Tawana
- Unit for Environmental Sciences and Management, North-West University, Potchefstroom 2531, South Africa
| | - ThankGod E. Onyiche
- Department of Veterinary Parasitology and Entomology, University of Maiduguri, Maiduguri 600230, Nigeria
| | - Tsepo Ramatla
- Unit for Environmental Sciences and Management, North-West University, Potchefstroom 2531, South Africa
- Correspondence: ; Tel.: +27-18-299-2521
| | - Sibusiso Mtshali
- Foundational Research and Services, South African National Biodiversity Institute, National Zoological Gardens, Pretoria 0001, South Africa
- University of Limpopo, Private Bag X1106, Sovenga 0727, South Africa
| | - Oriel Thekisoe
- Unit for Environmental Sciences and Management, North-West University, Potchefstroom 2531, South Africa
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Allan FK, Peters AR. Safety and Efficacy of the East Coast Fever Muguga Cocktail Vaccine: A Systematic Review. Vaccines (Basel) 2021; 9:vaccines9111318. [PMID: 34835249 PMCID: PMC8623010 DOI: 10.3390/vaccines9111318] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/21/2021] [Revised: 10/27/2021] [Accepted: 10/29/2021] [Indexed: 12/04/2022] Open
Abstract
Immunisation of livestock with high quality vaccines is considered an essential approach to controlling many animal diseases. The only currently available commercial vaccine to protect cattle from East Coast fever (ECF), a tick-borne disease caused by Theileria parva, is an unconventional “infection and treatment method” (ITM) involving administration of a combination of live T. parva isolates, referred to as the “Muguga cocktail”, and simultaneous treatment with long-acting oxytetracycline. Veterinary vaccine research and development typically involves studies designed to demonstrate vaccine quality, safety, and efficacy; however, as there were no such purpose-designed registration studies conducted for the Muguga cocktail, evidence for safety and efficacy is solely based on that which is available in the clinical literature. An extensive systematic review was conducted to analyse the evidence available in the literature in order to establish the safety and efficacy of the Muguga cocktail vaccine. A combination of meta-analyses and narrative summaries was conducted. A total of 61 studies met the criteria to be included in the systematic review. The majority of studies demonstrated or reported in favour of the vaccine with regards to safety and efficacy of the Muguga cocktail vaccine. Proximity to buffalo often resulted in reduced vaccine efficacy, and reports of shed and transmission of vaccine components affected the overall interpretation of safety. Better understanding of control options for this devastating livestock disease is important for policymakers and livestock keepers, enabling them to make informed decisions with regards to the health of their animals and their livelihoods.
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Goh S, Kolakowski J, Holder A, Pfuhl M, Ngugi D, Ballingall K, Tombacz K, Werling D. Development of a Potential Yeast-Based Vaccine Platform for Theileria parva Infection in Cattle. Front Immunol 2021; 12:674484. [PMID: 34305904 PMCID: PMC8297500 DOI: 10.3389/fimmu.2021.674484] [Citation(s) in RCA: 7] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/01/2021] [Accepted: 06/10/2021] [Indexed: 01/05/2023] Open
Abstract
East Coast Fever (ECF), caused by the tick-borne apicomplexan parasite Theileria parva, remains one of the most important livestock diseases in sub-Saharan Africa with more than 1 million cattle dying from infection every year. Disease prevention relies on the so-called "Infection and Treatment Method" (ITM), which is costly, complex, laborious, difficult to standardise on a commercial scale and results in a parasite strain-specific, MHC class I-restricted cytotoxic T cell response. We therefore attempted to develop a safe, affordable, stable, orally applicable and potent subunit vaccine for ECF using five different T. parva schizont antigens (Tp1, Tp2, Tp9, Tp10 and N36) and Saccharomyces cerevisiae as an expression platform. Full-length Tp2 and Tp9 as well as fragments of Tp1 were successfully expressed on the surface of S. cerevisiae. In vitro analyses highlighted that recombinant yeast expressing Tp2 can elicit IFNγ responses using PBMCs from ITM-immunized calves, while Tp2 and Tp9 induced IFNγ responses from enriched bovine CD8+ T cells. A subsequent in vivo study showed that oral administration of heat-inactivated, freeze-dried yeast stably expressing Tp2 increased total murine serum IgG over time, but more importantly, induced Tp2-specific serum IgG antibodies in individual mice compared to the control group. While these results will require subsequent experiments to verify induction of protection in neonatal calves, our data indicates that oral application of yeast expressing Theileria antigens could provide an affordable and easy vaccination platform for sub-Saharan Africa. Evaluation of antigen-specific cellular immune responses, especially cytotoxic CD8+ T cell immunity in cattle will further contribute to the development of a yeast-based vaccine for ECF.
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Affiliation(s)
- Shan Goh
- Department of Pathobiology and Population Sciences, Royal Veterinary College, Hatfield, United Kingdom
| | - Jeannine Kolakowski
- Department of Pathobiology and Population Sciences, Royal Veterinary College, Hatfield, United Kingdom
| | - Angela Holder
- Department of Pathobiology and Population Sciences, Royal Veterinary College, Hatfield, United Kingdom
| | - Mark Pfuhl
- Faculty of Life Science and Medicine, King's College London, London, United Kingdom
| | - Daniel Ngugi
- Department of Pathobiology and Population Sciences, Royal Veterinary College, Hatfield, United Kingdom
| | | | - Kata Tombacz
- Department of Pathobiology and Population Sciences, Royal Veterinary College, Hatfield, United Kingdom
| | - Dirk Werling
- Department of Pathobiology and Population Sciences, Royal Veterinary College, Hatfield, United Kingdom
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Oundo JW, Villinger J, Jeneby M, Ong’amo G, Otiende MY, Makhulu EE, Musa AA, Ouso DO, Wambua L. Pathogens, endosymbionts, and blood-meal sources of host-seeking ticks in the fast-changing Maasai Mara wildlife ecosystem. PLoS One 2020; 15:e0228366. [PMID: 32866142 PMCID: PMC7458302 DOI: 10.1371/journal.pone.0228366] [Citation(s) in RCA: 12] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/13/2020] [Accepted: 07/27/2020] [Indexed: 01/07/2023] Open
Abstract
The role of questing ticks in the epidemiology of tick-borne diseases in Kenya's Maasai Mara National Reserve (MMNR), an ecosystem with intensified human-wildlife-livestock interactions, remains poorly understood. We surveyed the diversity of questing ticks, their blood-meal hosts, and tick-borne pathogens to understand potential effects on human and livestock health. By flagging and hand-picking from vegetation in 25 localities, we collected 1,465 host-seeking ticks, mostly Rhipicephalus and Amblyomma species identified by morphology and molecular analysis. We used PCR with high-resolution melting (HRM) analysis and sequencing to identify Anaplasma, Babesia, Coxiella, Ehrlichia, Rickettsia, and Theileria pathogens and blood-meal remnants in 231 tick pools. We detected blood-meals from humans, wildebeest, and African buffalo in Rh. appendiculatus, goat in Rh. evertsi, sheep in Am. gemma, and cattle in Am. variegatum. Rickettsia africae was detected in Am. gemma (MIR = 3.10) that had fed on sheep and in Am. variegatum (MIR = 250) that had fed on cattle. We found Rickettsia spp. in Am. gemma (MIR = 9.29) and Rh. evertsi (MIR = 200), Anaplasma ovis in Rh. appendiculatus (MIR = 0.89) and Rh. evertsi (MIR = 200), Anaplasma bovis in Rh. appendiculatus (MIR = 0.89), and Theileria parva in Rh. appendiculatus (MIR = 24). No Babesia, Ehrlichia, or Coxiella pathogens were detected. Unexpectedly, species-specific Coxiella sp. endosymbionts were detected in all tick genera (174/231 pools), which may affect tick physiology and vector competence. These findings show that ticks from the MMNR are infected with zoonotic R. africae and unclassified Rickettsia spp., demonstrating risk of African tick-bite fever and other spotted-fever group rickettsioses to locals and visitors. The protozoan pathogens identified may also pose risk to livestock production. The diverse vertebrate blood-meals of questing ticks in this ecosystem including humans, wildlife, and domestic animals, may amplify transmission of tick-borne zoonoses and livestock diseases.
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Affiliation(s)
- Joseph Wang’ang’a Oundo
- International Centre of Insect Physiology and Ecology (icipe), Nairobi, Kenya
- School of Biological Sciences, University of Nairobi, Nairobi, Kenya
| | - Jandouwe Villinger
- International Centre of Insect Physiology and Ecology (icipe), Nairobi, Kenya
| | - Maamun Jeneby
- International Centre of Insect Physiology and Ecology (icipe), Nairobi, Kenya
- Institute of Primate Research, National Museums of Kenya, Nairobi, Kenya
| | - George Ong’amo
- School of Biological Sciences, University of Nairobi, Nairobi, Kenya
| | | | - Edward Edmond Makhulu
- International Centre of Insect Physiology and Ecology (icipe), Nairobi, Kenya
- Department of Biochemistry and Molecular Biology, Egerton University, Egerton, Kenya
| | - Ali Abdulahi Musa
- International Centre of Insect Physiology and Ecology (icipe), Nairobi, Kenya
- Department of Medical Laboratory Sciences, Kenyatta University, Nairobi, Kenya
| | - Daniel Obado Ouso
- International Centre of Insect Physiology and Ecology (icipe), Nairobi, Kenya
| | - Lillian Wambua
- International Centre of Insect Physiology and Ecology (icipe), Nairobi, Kenya
- School of Biological Sciences, University of Nairobi, Nairobi, Kenya
- * E-mail:
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Mukolwe LD, Odongo DO, Byaruhanga C, Snyman LP, Sibeko-Matjila KP. Analysis of p67 allelic sequences reveals a subtype of allele type 1 unique to buffalo-derived Theileria parva parasites from southern Africa. PLoS One 2020; 15:e0231434. [PMID: 32598384 PMCID: PMC7323972 DOI: 10.1371/journal.pone.0231434] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/23/2020] [Accepted: 06/13/2020] [Indexed: 11/18/2022] Open
Abstract
East Coast fever (ECF) and Corridor disease (CD) caused by cattle- and buffalo-derived T. parva respectively are the most economically important tick-borne diseases of cattle in the affected African countries. The p67 gene has been evaluated as a recombinant subunit vaccine against ECF, and for discrimination of T. parva parasites causing ECF and Corridor disease. The p67 allele type 1 was first identified in cattle-derived T. parva parasites from East Africa, where parasites possessing this allele type have been associated with ECF. Subsequent characterization of buffalo-derived T. parva parasites from South Africa where ECF was eradicated, revealed the presence of a similar allele type, raising concerns as to whether or not allele type 1 from parasites from the two regions is identical. A 900 bp central fragment of the gene encoding p67 was PCR amplified from T. parva DNA extracted from blood collected from cattle and buffalo in South Africa, Mozambique, Kenya, Tanzania and Uganda, followed by DNA sequence analysis. Four p67 allele types previously described were identified. A subtype of p67 allele type 1 was identified in parasites from clinical cases of CD and buffalo from southern Africa. Notably, p67 allele type 1 sequences from parasites associated with ECF in East Africa and CD in Kenya were identical. Analysis of two p67 B-cell epitopes (TpM12 and AR22.7) revealed amino acid substitutions in allele type 1 from buffalo-derived T. parva parasites from southern Africa. However, both epitopes were conserved in allele type 1 from cattle- and buffalo-derived T. parva parasites from East Africa. These findings reveal detection of a subtype of p67 allele type 1 associated with T. parva parasites transmissible from buffalo to cattle in southern Africa.
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Affiliation(s)
- Lubembe D. Mukolwe
- Vectors and Vector-borne Diseases Research Programme, Department of Veterinary Tropical Diseases, Faculty of Veterinary Science, University of Pretoria, Onderstepoort, South Africa
- Department of Veterinary Pathology, Microbiology & Parasitology, Faculty of Veterinary Medicine and Surgery, Egerton University, Egerton, Kenya
- * E-mail:
| | - David O. Odongo
- School of Biological Sciences, University of Nairobi, Nairobi, Kenya
| | - Charles Byaruhanga
- Vectors and Vector-borne Diseases Research Programme, Department of Veterinary Tropical Diseases, Faculty of Veterinary Science, University of Pretoria, Onderstepoort, South Africa
- National Agricultural Research Organization, Entebbe, Uganda
| | - Louwtjie P. Snyman
- Vectors and Vector-borne Diseases Research Programme, Department of Veterinary Tropical Diseases, Faculty of Veterinary Science, University of Pretoria, Onderstepoort, South Africa
- Durban Natural Science Museum, Durban, South Africa
| | - Kgomotso P. Sibeko-Matjila
- Vectors and Vector-borne Diseases Research Programme, Department of Veterinary Tropical Diseases, Faculty of Veterinary Science, University of Pretoria, Onderstepoort, South Africa
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