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Mendoza FJ, Pérez-Écija A, Kappmeyer LS, Suarez CE, Bastos RG. New insights in the diagnosis and treatment of equine piroplasmosis: pitfalls, idiosyncrasies, and myths. Front Vet Sci 2024; 11:1459989. [PMID: 39205808 PMCID: PMC11349644 DOI: 10.3389/fvets.2024.1459989] [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: 07/05/2024] [Accepted: 07/29/2024] [Indexed: 09/04/2024] Open
Abstract
Equine piroplasmosis (EP) is a global tick-borne disease of equids caused by the intraerythrocytic apicomplexan parasites Theileria equi and Babesia caballi, and the more recently discovered Theileria haneyi. These parasites can be transmitted by several tick species, including Dermacentor, Hyalomma, and Rhipicephalus, but iatrogenic and vertical transmission are also common. Clinical signs of EP include poor performance, fever, icterus, abortions, among others, and peracute or acute forms of infection are associated with high mortality in non-endemic areas. EP is a reportable disease and represents an important barrier for the international trade of horses and other equids, causing disruption of international equine sports. Tick control measures, serological and molecular diagnostic methods, and parasiticidal drugs are currently used against EP, while vaccines remain unavailable. Since most acaricides used in equids are non-environmentally friendly and linked to drug resistances, this is considered as an unsustainable approach. Imidocarb dipropionate (ID) and buparvaquone (BPQ) are currently the main drugs used to control the disease. However, while ID has several side and toxic effects and recurrent failures of treatment have been reported, BPQ is less effective in the clearance of T. equi infection and not available in some countries. Thus, novel alternative and effective therapeutics are needed. While current trade regulations require testing equids for EP before exportation, the lack of standardized PCR tests and limitations of the currently recommended serological assays entail a risk of inaccurate diagnosis. Hereby, we propose a combination of standardized PCR-based techniques and improved serological tests to diminish the risks of exporting EP-infected animals making equid international trade safer. In addition, this review discusses, based on scientific evidence, several idiosyncrasies, pitfalls and myths associated with EP, and identifies weaknesses of current methods of control and gaps of research, as initial steps toward developing novel strategies leading to control this disease.
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Affiliation(s)
- Francisco J. Mendoza
- Department of Animal Medicine and Surgery, College of Veterinary Medicine, University of Cordoba, Cordoba, Spain
| | - Alejandro Pérez-Écija
- Department of Animal Medicine and Surgery, College of Veterinary Medicine, University of Cordoba, Cordoba, Spain
| | - Lowell S. Kappmeyer
- Animal Disease Research Unit, Agricultural Research Service, United States Department of Agriculture (USDA), Pullman, WA, United States
| | - Carlos E. Suarez
- Animal Disease Research Unit, Agricultural Research Service, United States Department of Agriculture (USDA), Pullman, WA, United States
- Department of Veterinary Microbiology and Pathology, College of Veterinary Medicine, Washington State University, Pullman, WA, United States
| | - Reginaldo G. Bastos
- Animal Disease Research Unit, Agricultural Research Service, United States Department of Agriculture (USDA), Pullman, WA, United States
- Department of Veterinary Microbiology and Pathology, College of Veterinary Medicine, Washington State University, Pullman, WA, United States
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Dorrego A, Camino E, Gago P, Buendia-Andres A, Acurio K, Gonzalez S, de Juan L, Cruz-Lopez F. Haemato-biochemical characterization of equine piroplasmosis asymptomatic carriers and seropositive, real-time PCR negative horses. Vet Parasitol 2023; 323:110046. [PMID: 37826971 DOI: 10.1016/j.vetpar.2023.110046] [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: 06/06/2023] [Revised: 10/04/2023] [Accepted: 10/04/2023] [Indexed: 10/14/2023]
Abstract
Equine piroplasmosis (EP) is caused by Theileria equi and Babesia caballi, transmitted by tick vectors. Horses can suffer an acute, subacute, and chronic forms of the disease, with clinical signs such as poor performance, fever, pale mucosal membranes, and jaundice. The diagnosis of EP subclinical cases is complex due to the sensitivity of real-time PCR and the limited parasite load in some carriers, making it challenging to differentiate them from seropositive, PCR negative (S+PCR-) individuals. This study aimed to describe haematological and biochemical changes in asymptomatic EP carriers, EP S+PCR- horses and control horses (EP seronegative and PCR negative). It also investigated potential haemato-biochemical markers to aid in distinguishing true EP carriers alongside molecular and serological tests. A comprehensive haematology and biochemistry profile was conducted on 410 sera and EDTA blood samples, comprising 130 EP positives by real-time PCR and competitive ELISA (cELISA) (carriers), 130 EP negatives by real-time PCR but positive to cELISA (S+PCR-) and 150 EP negative horses to real-time PCR and c-ELISA (controls). Our study confirmed that a haematological and biochemistry profile could help to differentiate between EP carriers/S+PCR- from healthy horses. Carriers and S+PCR- horses showed significant increases in the white blood cell count (WBC), high total proteins (TP) and total globulins (GLOB) concentration, and liver function markers compared to controls. Additionally, the evaluation of uric acid (UA) suggested oxidative stress in carrier horses. However, no useful haemato-biochemical diagnostic markers were identified to aid the challenging differentiation of EP carriers and S+PCR- horses, highlighting the need for improvement in molecular/serological diagnosis for these horses.
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Affiliation(s)
- Abel Dorrego
- VISAVET Health Surveillance Centre, Universidad Complutense, Madrid, Spain
| | | | - Paloma Gago
- VISAVET Health Surveillance Centre, Universidad Complutense, Madrid, Spain; Animal Health Department, Facultad de Veterinaria, Universidad Complutense, Madrid, Spain
| | | | - Kiara Acurio
- VISAVET Health Surveillance Centre, Universidad Complutense, Madrid, Spain
| | - Sergio Gonzalez
- VISAVET Health Surveillance Centre, Universidad Complutense, Madrid, Spain
| | - Lucia de Juan
- VISAVET Health Surveillance Centre, Universidad Complutense, Madrid, Spain; Animal Health Department, Facultad de Veterinaria, Universidad Complutense, Madrid, Spain
| | - Fatima Cruz-Lopez
- VISAVET Health Surveillance Centre, Universidad Complutense, Madrid, Spain.
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Cocco R, Rizzo M, Carta C, Arfuso F, Piccione G, Luridiana S, Crovace A, Passino ES, Sechi S. Immune and Inflammatory Response of Donkeys (Equus asinus) Tested Positive to Tick-borne Pathogens. J Equine Vet Sci 2023; 120:104190. [PMID: 36509242 DOI: 10.1016/j.jevs.2022.104190] [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: 10/12/2022] [Revised: 12/02/2022] [Accepted: 12/06/2022] [Indexed: 12/13/2022]
Abstract
Among infection diseases transmitted by arthropods, the equine vector-borne diseases transmitted by ticks represent an emerging problem worldwide due to their morbidity and mortality and, in some cases, to their zoonotic relevance. Understanding the host immune/inflammatory response to the pathogens is crucial to develop effective methods of diagnosis, control and treatment. This study aimed to evaluate red blood cells (RBC), hematocrit (Hct), hemoglobin concentration (Hb), mean cell volume (MCV), mean cell hemoglobin content (MCH), mean cell hemoglobin (MCHC), platelets (PLT), white blood cells (WBC), leukocytes populations, and serum protein pattern of Sardinian donkeys scored positive to tick-borne pathogens. Thirty donkeys were dived in five groups, six subjects each: Group 1, tested negative to pathogens (control group); Group 2, donkeys infected by Theileria equi; Group 3, donkeys infected by Ehrlichia equi; Group 4, donkeys infected by Rickettsia Rickettsii; Group 5, donkeys co-infected by T. equi, E. equi and R. Rickettsii. From donkeys blood samples were collected and haematological and serum protein profiles were assessed. One-way ANOVA showed lower red blood cells, haemoglobin, platelets, lymphocytes and neutrophils values, and higher eosinophils, basophils, serum total proteins, α2-, β- and γ- globulins values in donkeys infected by one or more pathogens compared to control group (P < .05). The study highlighted an immune and inflammatory response of donkeys positive to E. equi, T. equi, and R. Rickettsii and represents a starting point for further investigations in the field to fill the gaps currently existing on the complex interwoven relationship between the pathogen and host immune and inflammatory response in equids.
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Affiliation(s)
- Raffaella Cocco
- Department of Veterinary Sciences, University of Sassari, Sassari, Italy
| | - Maria Rizzo
- Department of Veterinary Sciences, University of Messina, Polo University Annunziata, Messina, Italy
| | - Carlo Carta
- Department of Veterinary Sciences, University of Sassari, Sassari, Italy
| | - Francesca Arfuso
- Department of Veterinary Sciences, University of Messina, Polo University Annunziata, Messina, Italy
| | - Giuseppe Piccione
- Department of Veterinary Sciences, University of Messina, Polo University Annunziata, Messina, Italy.
| | | | - Alberto Crovace
- Department of Veterinary Sciences, University of Sassari, Sassari, Italy
| | | | - Sara Sechi
- Department of Veterinary Sciences, University of Sassari, Sassari, Italy
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Sears KP, Knowles DP, Fry LM. Clinical Progression of Theileria haneyi in Splenectomized Horses Reveals Decreased Virulence Compared to Theileria equi. Pathogens 2022; 11:pathogens11020254. [PMID: 35215197 PMCID: PMC8879895 DOI: 10.3390/pathogens11020254] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/18/2022] [Revised: 02/11/2022] [Accepted: 02/15/2022] [Indexed: 02/01/2023] Open
Abstract
The global importance of the hemoparasite Theileria haneyi to equine health was recently shown by its resistance to imidocarb dipropionate (ID) and its interference with T. equi clearance by ID in some co-infected horses. Genetic characterization of T. haneyi revealed marked genomic reduction compared to T. equi, and initial experiments demonstrated reduced clinical severity in spleen-intact horses. Furthermore, in early experiments, splenectomized horses survived T. haneyi infection and progressed to an asymptomatic carrier state, in stark contrast to the high fatality rate of T. equi in splenectomized horses. Thus, we hypothesized that T. haneyi is less virulent than T. equi. To objectively assess virulence, clinical data from nine splenectomized, T. haneyi-infected horses were evaluated and compared to published data on T. equi-infected, splenectomized horses. Seven of eight splenectomized, T. haneyi-infected horses survived. Further, in six horses co-infected with T. equi and T. haneyi, only horses cleared of T. equi by ID survived splenectomy and became asymptomatic carriers. The reduced virulence of T. haneyi in splenectomized horses instructs why T. haneyi was, until recently, undetected. This naturally occurring comparative reduction in virulence in a natural host provides a foundation for defining virulence mechanisms of theileriosis and Apicomplexa in general.
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Affiliation(s)
- Kelly P. Sears
- Department of Clinical Science, Carlson College of Veterinary Medicine, Oregon State University, Corvallis, OR 97331-4801, USA;
- Department of Veterinary Microbiology and Pathology, Washington State University, College of Veterinary Medicine, Pullman, WA 99164-6630, USA;
| | - Donald P. Knowles
- Department of Veterinary Microbiology and Pathology, Washington State University, College of Veterinary Medicine, Pullman, WA 99164-6630, USA;
| | - Lindsay M. Fry
- Department of Veterinary Microbiology and Pathology, Washington State University, College of Veterinary Medicine, Pullman, WA 99164-6630, USA;
- USDA—ARS, Animal Disease Research Unit, Pullman, WA 99164-6630, USA
- Correspondence: ; Tel.: +1-509-595-1822
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Nadal C, Marsot M, Le Metayer G, Boireau P, Guillot J, Bonnet SI. Spatial and Temporal Circulation of Babesia caballi and Theileria equi in France Based on Seven Years of Serological Data. Pathogens 2022; 11:227. [PMID: 35215171 PMCID: PMC8876836 DOI: 10.3390/pathogens11020227] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/07/2022] [Revised: 01/25/2022] [Accepted: 02/07/2022] [Indexed: 02/05/2023] Open
Abstract
Caused by two blood parasites, Babesia caballi and Theileria equi, equine piroplasmosis is a tick-borne disease that poses major health and economic issues for the equine industry. Our objective was to gain insight into the spatio-temporal variations of parasite circulation in France, where the disease is known to be enzootic, but has been the subject of few studies. Seroprevalence was assessed for each parasite thanks to 16,127 equine sera obtained between 1997 and 2003 from all over France and analysed through complement fixation tests. Results indicated that 13.2% (5-27% depending on the region) of horses were seropositive for T. equi and 9.5% (3-25%) for B. caballi. Regardless of the year, horses from the southern regions of France were the most affected by B. caballi or T. equi infection, while the proportion of horses having antibodies against T. equi increased over time. These results highlight the heterogeneity of the circulation of both piroplasms, which may be linked with ecological diversity and vector distribution. Our data provide baseline information regarding the sero-epidemiology of B. caballi and T. equi infection in horses in France, making it now possible to select regions for future studies on risk factors, and design and implement effective targeted measures against equine piroplasms.
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Affiliation(s)
- Clémence Nadal
- Epidemiology Unit, Laboratory for Animal Health, University Paris Est, ANSES, 94700 Paris, France; (C.N.); (M.M.)
- ANSES, INRAE, Ecole Nationale Vétérinaire d’Alfort, UMR BIPAR, Laboratory for Animal Health, 94700 Paris, France
| | - Maud Marsot
- Epidemiology Unit, Laboratory for Animal Health, University Paris Est, ANSES, 94700 Paris, France; (C.N.); (M.M.)
| | - Gaël Le Metayer
- Parasitology Department, Ecole Nationale Vétérinaire d’Alfort, 94700 Paris, France; (G.L.M.); (J.G.)
- Veterinary Clinic of La Cère, 15800 Polminhac, France
| | - Pascal Boireau
- Laboratory for Animal Health, University Paris Est, ANSES, 94700 Paris, France;
| | - Jacques Guillot
- Parasitology Department, Ecole Nationale Vétérinaire d’Alfort, 94700 Paris, France; (G.L.M.); (J.G.)
- Dermatology Parasitology Mycology Departement, Ecole Nationale Vétérinaire de Nantes, Oniris, 44307 Nantes, France
| | - Sarah I. Bonnet
- ANSES, INRAE, Ecole Nationale Vétérinaire d’Alfort, UMR BIPAR, Laboratory for Animal Health, 94700 Paris, France
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Santos AC, Nogueira CEW, Dos Santos Suñe Moraes B, Müller V, Mousquer MA, Leite FPL. Immune response of adult horses, pregnant mares and foals to an experimental vaccine with recombinant EMA-2 protein of Theileria equi. Res Vet Sci 2021; 139:186-192. [PMID: 34343932 DOI: 10.1016/j.rvsc.2021.07.013] [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: 03/24/2021] [Revised: 06/28/2021] [Accepted: 07/13/2021] [Indexed: 10/20/2022]
Abstract
Equine theileriosis, caused by the Theileria equi protozoan, is a disease of worldwide importance. T. equi expresses surface proteins, of which the EMA-2 protein is a promising antigen for vaccine use. The aim of this study was to evaluate the immune response of adult horses, pregnant mares, and foals to an experimental EMA-2 protein of recombinant T. equi vaccine. A total of 46 horses were used in this study for vaccine trials and challenges. Twelve geldings, 14 pregnant mares, and 14 foals were divided into vaccinated and control groups. Total serum specific anti-rEMA-2 IgG, IgG subclasses, and transcription of cytokines related to the immune response were evaluated. For the vaccine challenge, six six-month-old foals were divided into vaccinated and control groups. For the challenge, blood from a horse with theileriosis was transfused to the foals. Geldings and pregnant mares maintained anti-rEMA-2 IgG levels at 130 and 140 days after vaccination, respectively. The most-detected IgG subclasses in vaccinated were IgG3/5, IgG4/7, and IgG1. IL2, IL10, IL12, IL17, IFN-γ, and TNF-α were the most-transcribed cytokines in PBMCs of vaccinated horses stimulated with rEMA-2. Challenge with T. equi demonstrated that vaccinated foals had an increase of 33% in total IgG four days after blood transfusion, while control foals had no significant response, suggesting that vaccine antibodies may have recognized EMA-2 protein of the native T. equi antigen. T. equi recombinant EMA-2 was shown to be a promising vaccine antigen by inducing humoral and cellular immunity similar to that observed in natural parasite infections.
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Affiliation(s)
- Alice Corrêa Santos
- Centro de Desenvolvimento Tecnológico, Biotecnologia, Pelotas, Rio Grande do Sul, Brazil
| | - Carlos Eduardo Wayne Nogueira
- Departamento de Clínicas Veterinária, Faculdade de Medicina Veterinária, Universidade Federal de Pelotas, Pelotas, Rio Grande do Sul, Brazil
| | - Bruna Dos Santos Suñe Moraes
- Departamento de Clínicas Veterinária, Faculdade de Medicina Veterinária, Universidade Federal de Pelotas, Pelotas, Rio Grande do Sul, Brazil
| | - Vitória Müller
- Centro de Desenvolvimento Tecnológico, Biotecnologia, Pelotas, Rio Grande do Sul, Brazil
| | - Mariana Andrade Mousquer
- Departamento de Clínicas Veterinária, Faculdade de Medicina Veterinária, Universidade Federal de Pelotas, Pelotas, Rio Grande do Sul, Brazil
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Imidocarb Dipropionate Lacks Efficacy against Theileria haneyi and Fails to Consistently Clear Theileria equi in Horses Co-Infected with T. haneyi. Pathogens 2020; 9:pathogens9121035. [PMID: 33321715 PMCID: PMC7764667 DOI: 10.3390/pathogens9121035] [Citation(s) in RCA: 12] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/12/2020] [Revised: 12/05/2020] [Accepted: 12/08/2020] [Indexed: 12/27/2022] Open
Abstract
Control of Theileria equi, the primary cause of equine theileriosis, is largely reliant on acaracide use and chemosterilization with imidocarb dipropionate (ID). However, it is currently unknown if ID is effective against Theileria haneyi, the recently identified second causative agent of equine theileriosis, or if the drug maintains effectiveness against T. equi in the presence of T. haneyi co-infection. The purpose of this study was to address these questions using ID treatment of the following three groups of horses: (1) five T. haneyi infected horses; (2) three T. haneyi-T. equi infected horses; and (3) three T. equi-T. haneyi infected horses. Clearance was first evaluated using nPCR for each Theileria sp. on peripheral blood samples. ID failed to clear T. haneyi in all three groups of horses, and failed to clear T. equi in two of three horses in group two. For definitive confirmation of infection status, horses in groups two and three underwent splenectomy post-treatment. The T. equi-nPCR-positive horses in group two developed severe clinical signs and were euthanized. Remaining horses exhibited moderate signs consistent with T. haneyi. Our results demonstrate that ID therapy lacks efficacy against T. haneyi, and T. haneyi-T. equi co-infection may interfere with ID clearance of T. equi.
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Song J, Song R, Wang P, Zhang Y, Yan Y, Zhou J, Chahan B, Liao M. Preparation of Monoclonal Antibody Against EMA-1 and Development of Rapid Serological Detection Method for Theileria equi Infection, Xinjiang, China. J Parasitol 2020; 106:283-290. [PMID: 32296849 DOI: 10.1645/19-98] [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] [Indexed: 11/10/2022] Open
Abstract
The erythrocytic-stage surface protein equi merozoite antigen 1 (EMA-1) of Theileria equi is a major candidate for the development of a diagnostic antigen for equine piroplasmosis. In this study, BALB/c mice were immunized with purified recombinant EMA-1 to prepare monoclonal antibody (mAb) against T. equi EMA-1, and 1 mAb 5H2 was obtained that showed good reaction with infected red blood cells (RBC) in the indirect immunofluorescence assay (IFA). To develop a rapid serological detection method for T. equi infection in Xinjiang Uygur Autonomous Region, China, recombinant EMA-1 originating from the local T. equi strain and the mAb to EMA-1 were employed to develop an immunochromatographic test (ICT) to detect antibodies to T. equi in horse sera. The ICT showed high sensitivity and specificity and no cross-reaction with Babesia caballi. Ninety-two horse serum samples collected from Ili, Xinjiang, were tested by ICT and compared with the detection results of a commercial ELISA kit. The results showed that 56 of 92 (61%) serum samples were seropositive according to the ICT assay, and 50 (54%) samples were seropositive according to the ELISA kit. The ICT had a high coincidence (91.3%) but was more sensitive than the reference ELISA kit. To confirm whether the horses were infected by T. equi, 30 blood DNA samples from 92 horses were examined by PCR. The results showed that 14 of 30 (47%) horses were confirmed to be infected with T. equi by PCR, while 16 of 30 (53%) horses were seropositive by ICT. All PCR-positive horses were ICT-positive. The findings indicate that T. equi is endemic in Ili, Xinjiang, and that the ICT is reliable as a serological diagnosis method. The ICT developed in this study could be an efficient diagnostic tool to detect T. equi infection in horses in the Xinjiang area.
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Affiliation(s)
- Jingjing Song
- Parasites Laboratory, Veterinary College, Xinjiang Agricultural University, Nongda East 311, Urumqi, Xinjiang, 830052, P. R. China
| | - Ruiqi Song
- Parasites Laboratory, Veterinary College, Xinjiang Agricultural University, Nongda East 311, Urumqi, Xinjiang, 830052, P. R. China
| | - Panju Wang
- Parasites Laboratory, Veterinary College, Xinjiang Agricultural University, Nongda East 311, Urumqi, Xinjiang, 830052, P. R. China
| | - Yang Zhang
- Parasites Laboratory, Veterinary College, Xinjiang Agricultural University, Nongda East 311, Urumqi, Xinjiang, 830052, P. R. China
| | - Yan Yan
- Key Laboratory of Animal Virology of Ministry of Agriculture, Zhejiang University, Hangzhou, 310058, P. R. China
| | - Jiyong Zhou
- Key Laboratory of Animal Virology of Ministry of Agriculture, Zhejiang University, Hangzhou, 310058, P. R. China
| | - Bayin Chahan
- Parasites Laboratory, Veterinary College, Xinjiang Agricultural University, Nongda East 311, Urumqi, Xinjiang, 830052, P. R. China
| | - Min Liao
- Key Laboratory of Animal Virology of Ministry of Agriculture, Zhejiang University, Hangzhou, 310058, P. R. China
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Vianna AM, Santos AC, Cunha RC, de Souza Stori de Lara AP, Weege GB, Leivas Leite FP. Antigenicity assessment of the Theileria equi merozoite antigen (EMA-2) expressed in Pichia pastoris in mice and horses. Exp Parasitol 2019; 206:107757. [PMID: 31494216 DOI: 10.1016/j.exppara.2019.107757] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/13/2019] [Revised: 09/02/2019] [Accepted: 09/03/2019] [Indexed: 11/18/2022]
Abstract
Equine theileriosis is a severe equine disease caused by the protozoan Theileria equi, which is prevalent in tropical and subtropical areas. In this study, a recombinant equi merozoite antigen-2 (rEMA-2) of T. equi was used as an immunogen. Two groups of 10 mice each were divided into control and vaccinated groups. Sixty mares seronegative for theileriosis were divided in two groups, one vaccinated and another group as a control animal. Mice and mares of the vaccinated groups were inoculated with 150 μL of the vaccine containing 50 μg of rEMA-2 and 2 mL of the vaccine containing 200 μg of rEMA-2, respectively, at days 0 and 21. The immunogenicity of rEMA-2 was evaluated by ELISA and fluorescent antibody test (IFAT) using serum from vaccinated mice, mares and antigenicity in naturally infected horse. At every point throughout the ELISA study, there were significant differences between the vaccinated and control groups (p < 0.05). The vaccine induced 3- and 4-fold IgG increases in mice at the 14th and 28th day, respectively, compared to the control group. The horses' IgG dynamics showed a significant (p < 0.05) increase in the total IgG titer as early as day 7, which increased until day 28 at which time a more significant (p < 0.001) IgG titer was observed. In evaluating the isotypes, we observed a trend similar to that of total IgG, where IgG(T) (IgG3-5) were significantly (p < 0.05) more elevated than the other isotypes analyzed, followed by IgGb (IgG4-7) and IgGa (IgG1). Positive fluorescence was detected by IFAT, suggesting that the protein is immunogenic and conserves some epitopes identical to the native T. equi antigens present in the equine blood smear. Thus, our results suggest that rEMA-2 can be a promising vaccinal antigen.
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Affiliation(s)
- Ana Muñoz Vianna
- Laboratório de Bacteriologia, Núcleo de Biotecnologia, Centro de Desenvolvimento Tecnológico, Universidade Federal de Pelotas, Pelotas, 96010-900, Brazil.
| | - Alice Correa Santos
- Laboratório de Bacteriologia, Núcleo de Biotecnologia, Centro de Desenvolvimento Tecnológico, Universidade Federal de Pelotas, Pelotas, 96010-900, Brazil.
| | - Rodrigo Casquero Cunha
- Laboratório de Bacteriologia, Núcleo de Biotecnologia, Centro de Desenvolvimento Tecnológico, Universidade Federal de Pelotas, Pelotas, 96010-900, Brazil.
| | | | - Guilherme Borges Weege
- Departamento de Microbiologia e Parasitologia, Universidade Federal de Pelotas, Pelotas, RS, Brazil.
| | - Fábio Pereira Leivas Leite
- Laboratório de Bacteriologia, Núcleo de Biotecnologia, Centro de Desenvolvimento Tecnológico, Universidade Federal de Pelotas, Pelotas, 96010-900, Brazil; Departamento de Microbiologia e Parasitologia, Universidade Federal de Pelotas, Pelotas, RS, Brazil.
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10
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Onyiche TE, Suganuma K, Igarashi I, Yokoyama N, Xuan X, Thekisoe O. A Review on Equine Piroplasmosis: Epidemiology, Vector Ecology, Risk Factors, Host Immunity, Diagnosis and Control. INTERNATIONAL JOURNAL OF ENVIRONMENTAL RESEARCH AND PUBLIC HEALTH 2019; 16:E1736. [PMID: 31100920 PMCID: PMC6572709 DOI: 10.3390/ijerph16101736] [Citation(s) in RCA: 70] [Impact Index Per Article: 14.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 02/09/2019] [Revised: 04/18/2019] [Accepted: 04/20/2019] [Indexed: 11/25/2022]
Abstract
Equine Piroplasmosis (EP) is a tick-borne disease caused by apicomplexan protozoan parasites, Babesia caballi and Theileria equi. The disease is responsible for serious economic losses to the equine industry. It principally affects donkeys, horses, mules, and zebra but DNA of the parasites has also been detected in dogs and camels raising doubt about their host specificity. The disease is endemic in tropical and temperate regions of the world where the competent tick vectors are prevalent. Infected equids remain carrier for life with T. equi infection, whilst, infection with B. caballi is cleared within a few years. This review focuses on all aspects of the disease from the historical overview, biology of the parasite, epidemiology of the disease (specifically highlighting other non-equine hosts, such as dogs and camels), vector, clinical manifestations, risk factors, immunology, genetic diversity, diagnosis, treatment, and prevention.
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Affiliation(s)
- ThankGod E Onyiche
- Unit for Environmental Sciences and Management, North West University, Potchefstroom Campus, Private Bag X6001, Potchefstroom 2520, South Africa.
- Department of Veterinary Parasitology and Entomology, University of Maiduguri, P. M. B. 1069, Maiduguri 600230, Nigeria.
| | - Keisuke Suganuma
- National Research Center for Protozoan Diseases, Obihiro University of Agriculture and Veterinary Medicine, Obihiro, Hokkaido 080-8555, Japan.
| | - Ikuo Igarashi
- National Research Center for Protozoan Diseases, Obihiro University of Agriculture and Veterinary Medicine, Obihiro, Hokkaido 080-8555, Japan.
| | - Naoaki Yokoyama
- National Research Center for Protozoan Diseases, Obihiro University of Agriculture and Veterinary Medicine, Obihiro, Hokkaido 080-8555, Japan.
| | - Xuenan Xuan
- National Research Center for Protozoan Diseases, Obihiro University of Agriculture and Veterinary Medicine, Obihiro, Hokkaido 080-8555, Japan.
| | - Oriel Thekisoe
- Unit for Environmental Sciences and Management, North West University, Potchefstroom Campus, Private Bag X6001, Potchefstroom 2520, South Africa.
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Assessment of equine piroplasmids in the Nhecolândia sub-region of Brazilian Pantanal wetland using serological, parasitological, molecular, and hematological approaches. Ticks Tick Borne Dis 2019; 10:714-721. [PMID: 30876824 DOI: 10.1016/j.ttbdis.2019.03.002] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/25/2017] [Revised: 02/25/2019] [Accepted: 03/04/2019] [Indexed: 11/24/2022]
Abstract
Brazilian Pantanal is the world´s largest wetland ecosystem, where cattle's ranching is the most important economic activity. The objective of this study was to compile some epidemiological features on equine piroplasmids from the Nhecolândia sub-region of Pantanal wetland through the evaluation of the patterns of T. equi and B. caballi infections in different groups of horses; identification of the tick species that infest horses; and to study phylogenetic relationships among Theileria equi 18S rRNA gene sequences. During October 2015, blood and serum samples were collected from 170 horses in four different categories. Ticks, after identification, had their hemolymph and eggs examined for the presence of piroplasmid sporokinets. Also we searched parasites in the peripheral blood smears of the investigated horses. The number of red blood cells (RBCs) and the packed cell volume (PCV) were determined to test for anemia in the infected animals, and exposure to B. caballi and T. equi was evaluated by enzyme-linked immunosorbent assay. "Catch all primers" based on 18S rRNA gene were used in polymerase chain reactions (PCR) to detect equine piroplasmids, followed by three nested PCRs for the phylogenetic analysis. The serological results showed that 61.8% and 52.9% of the horses sampled were exposed to T. equi and B. caballi, respectively. Piroplasmid DNA was detected in 43.5% of the horses analyzed. Our sequencing revealed 98-100% identity with some sequences previously published in GenBank for T. equi, and microheterogeneity among others. We found that 51.2% of the animals sampled were infested with Dermacentor nitens, Amblyomma sculptum, and Rhipicephalus (Boophilus) microplus, singly or co-infested. Since positive and negative animals presented similar RBC and PCV values, and no sporokinets were found on blood smears, hemolymph and eggs of the ticks collected, we suggest that infected equines can act as asymptomatic carriers for piroplasmosis in the studied region. Our results together showed the enzootic characteristic of equine piroplasmids in Pantanal region highlighting the importance of using different methods for detection these parasites. Moreover, breeding mares and foals should be monitored since they displayed the greatest occurrences for molecular test (59.0% and 86.1% respectively) and tick infestations (87.2% and 63.9% respectively).
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12
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Evolution and diversity of the EMA families of the divergent equid parasites, Theileria equi and T. haneyi. INFECTION GENETICS AND EVOLUTION 2019; 68:153-160. [DOI: 10.1016/j.meegid.2018.12.020] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/12/2018] [Revised: 12/04/2018] [Accepted: 12/17/2018] [Indexed: 11/30/2022]
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13
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Wise LN, Kappmeyer LS, Silva MG, White SN, Grause JF, Knowles DP. Verification of post-chemotherapeutic clearance of Theileria equi through concordance of nested PCR and immunoblot. Ticks Tick Borne Dis 2017; 9:135-140. [PMID: 28887100 DOI: 10.1016/j.ttbdis.2017.08.007] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/13/2017] [Revised: 07/24/2017] [Accepted: 08/17/2017] [Indexed: 11/27/2022]
Abstract
Certain countries including the United States remain non-endemic for particular infectious diseases such as equine piroplasmosis through import restrictions and surveillance. Endemic regions often employ premunition as the primary method to control disease, however in non-endemic countries, chemosterilization combined with methods to confirm parasite elimination are required to maintain disease-free status. The ability of imidocarb diproprionate (ID) to clear persistent Theileria equi infection from infected horses has been shown through the inability of treated horses to transmit via blood transfer. However, the common lengthy persistence of anti-T. equi antibody causes regulatory tests such as cELISA or IFA to remain positive for extended periods. Persistence of positive testing creates challenges for regulatory veterinary medicine and international trade. Concordance between nested polymerase chain reaction (nPCR) targeting the ema1 gene and immunoblotting (IB) measuring declination in anti-EMA1 and anti-EMA2 antibody were used to verify clearance of T. equi from 179 ID-treated horses. These data support the use of IB to demonstrate declining anti-EMA1 and EMA2 titers in T. equi-infected horses subsequent to successful ID treatment. Such data provide concordant support to a negative nPCR and allow for a more timely determination of effective ID clearance of T. equi. The post ID treatment results indicate that while nPCR was consistently negative by 14 days and cELISA generally remained positive after 1 year, immunoblot was on average negative after 4 months and 100% in agreement with nPCR.
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Affiliation(s)
- L N Wise
- Animal Disease Research Unit, Agricultural Research Service, U.S. Department of Agriculture, Pullman, WA, USA; School of Veterinary Medicine, St. George's University, True Blue, Grenada, W. I..
| | - L S Kappmeyer
- Animal Disease Research Unit, Agricultural Research Service, U.S. Department of Agriculture, Pullman, WA, USA
| | - M G Silva
- Animal Disease Research Unit, Agricultural Research Service, U.S. Department of Agriculture, Pullman, WA, USA; Department of Veterinary Microbiology and Pathology, College of Veterinary Medicine, Washington State University, Pullman, WA, USA
| | - S N White
- Animal Disease Research Unit, Agricultural Research Service, U.S. Department of Agriculture, Pullman, WA, USA; Department of Veterinary Microbiology and Pathology, College of Veterinary Medicine, Washington State University, Pullman, WA, USA
| | - J F Grause
- Animal and Plant Health Inspection Service, Veterinary Services, Science, Technology and Analysis Services, National Veterinary Services Laboratories, Ames, IA, USA
| | - D P Knowles
- Animal Disease Research Unit, Agricultural Research Service, U.S. Department of Agriculture, Pullman, WA, USA; Department of Veterinary Microbiology and Pathology, College of Veterinary Medicine, Washington State University, Pullman, WA, USA
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14
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Pasolini MP, Pagano TB, Costagliola A, Biase DD, Lamagna B, Auletta L, Fatone G, Greco M, Coluccia P, Vincenzo V, Pirozzi C, Raso GM, Santoro P, Manna G, Papparella S, Paciello O. Inflammatory Myopathy in Horses With Chronic Piroplasmosis. Vet Pathol 2017; 55:133-143. [PMID: 28718360 DOI: 10.1177/0300985817716262] [Citation(s) in RCA: 14] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/20/2022]
Abstract
Horses affected by chronic piroplasmosis may develop poor performance and muscle atrophy. Here we investigate the pathological and immunopathological aspects of myopathy occurring in chronic equine piroplasmosis. The study included 16 horses serologically positive for equine piroplasms presenting with clinical signs and supporting serum biochemical evidence of a myopathy. Skeletal muscle was evaluated by histopathology, immunohistochemistry, indirect immunofluorescence, and molecular detection of piroplasms and inflammatory cytokines in skeletal muscle. Histologic lesions included muscle fiber atrophy (100% of cases), degenerative changes (13/16, 81%), and perivascular perimysial and endomysial lymphocytic infiltrates (81% of cases). In 15 cases (94%), muscle fibers had strong immunostaining for major histocompatibility complex classes I and II. T lymphocyte populations were mainly CD3+, CD8+, and CD4+ in equal proportions, with a lower number of CD79α+ cells. The serum from affected horses was tested by indirect immunofluorescence for binding of IgG, IgM, or IgA to sections of normal equine muscle to detect circulating autoantibodies against muscle antigen(s). In all cases, distinct sarcolemmal staining was detected in sections incubated with serum from affected horses, in contrast to sections incubated with phosphate-buffered saline or equine control sera. Reverse transcription polymerase chain reaction (RT-PCR) testing of muscles from affected animals revealed a significant increase of interferon-γ, interleukin-12, and tumor necrosis factor-α gene expression compared to healthy controls. Theileria equi or Babesia caballi was not detected in samples of affected muscle by RT-PCR. Thus, inflammatory myopathy associated with equine piroplasmosis may involve an autoimmune pathogenesis with upregulation of inflammatory cytokines that may cause myofiber atrophy and degeneration.
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Affiliation(s)
- Maria P Pasolini
- 1 Unit of Surgery, Department of Veterinary Medicine and Animal Productions, University of Naples Federico II, Naples, Italy
| | - Teresa B Pagano
- 2 Unit of Pathology, Department of Veterinary Medicine and Animal Productions, University of Naples Federico II, Naples, Italy
| | - Alessandro Costagliola
- 2 Unit of Pathology, Department of Veterinary Medicine and Animal Productions, University of Naples Federico II, Naples, Italy
| | - Davide De Biase
- 2 Unit of Pathology, Department of Veterinary Medicine and Animal Productions, University of Naples Federico II, Naples, Italy
| | - Barbara Lamagna
- 1 Unit of Surgery, Department of Veterinary Medicine and Animal Productions, University of Naples Federico II, Naples, Italy
| | | | - Gerardo Fatone
- 1 Unit of Surgery, Department of Veterinary Medicine and Animal Productions, University of Naples Federico II, Naples, Italy
| | - Michele Greco
- 1 Unit of Surgery, Department of Veterinary Medicine and Animal Productions, University of Naples Federico II, Naples, Italy
| | - Pierpaolo Coluccia
- 1 Unit of Surgery, Department of Veterinary Medicine and Animal Productions, University of Naples Federico II, Naples, Italy
| | - Veneziano Vincenzo
- 3 Unit of Parasitology, Department of Veterinary Medicine and Animal Productions, University of Naples Federico II, Naples, Italy
| | - Claudio Pirozzi
- 4 Department of Pharmacy, University of Naples Federico II, Naples, Italy
| | | | | | - Giuseppe Manna
- 6 National Reference Centre for Equine Diseases, Istituto Zooprofilattico Sperimentale "M. Aleandri," Rome, Italy
| | - Serenella Papparella
- 2 Unit of Pathology, Department of Veterinary Medicine and Animal Productions, University of Naples Federico II, Naples, Italy
| | - Orlando Paciello
- 2 Unit of Pathology, Department of Veterinary Medicine and Animal Productions, University of Naples Federico II, Naples, Italy
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15
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Wise LN, Pelzel-McCluskey AM, Mealey RH, Knowles DP. Equine Piroplasmosis. Vet Clin North Am Equine Pract 2014; 30:677-93. [DOI: 10.1016/j.cveq.2014.08.008] [Citation(s) in RCA: 53] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/16/2022] Open
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Affiliation(s)
- Y. Tamzali
- Equine Internal Medicine; Université de Toulouse; INP, ENVT; France
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17
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Wise LN, Kappmeyer LS, Mealey RH, Knowles DP. Review of equine piroplasmosis. J Vet Intern Med 2013; 27:1334-46. [PMID: 24033559 DOI: 10.1111/jvim.12168] [Citation(s) in RCA: 159] [Impact Index Per Article: 14.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/05/2013] [Revised: 04/15/2013] [Accepted: 07/16/2013] [Indexed: 10/26/2022] Open
Abstract
Equine piroplasmosis is caused by one of 2 erythrocytic parasites Babesia caballi or Theileria equi. Although the genus of the latter remains controversial, the most recent designation, Theileria, is utilized in this review. Shared pathogenesis includes tick-borne transmission and erythrolysis leading to anemia as the primary clinical outcome. Although both parasites are able to persist indefinitely in their equid hosts, thus far, only B. caballi transmits across tick generations. Pathogenesis further diverges after transmission to equids in that B. caballi immediately infects erythrocytes, whereas T.equi infects peripheral blood mononuclear cells. The recent re-emergence of T.equi in the United States has increased awareness of these tick-borne pathogens, especially in terms of diagnosis and control. This review focuses in part on factors leading to the re-emergence of infection and disease of these globally important pathogens.
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Affiliation(s)
- L N Wise
- Department of Veterinary Microbiology and Pathology, Washington State University, Pullman, WA; Animal Disease Research Unit, U.S. Department of Agriculture, Agricultural Research Service, Pullman, WA
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18
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Serum proteinogram, acute phase proteins and immunoglobulins in dogs experimentally infected with Rangelia vitalii. Vet Parasitol 2013; 192:137-42. [DOI: 10.1016/j.vetpar.2012.09.036] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/10/2012] [Revised: 09/25/2012] [Accepted: 09/27/2012] [Indexed: 11/18/2022]
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BANNAI H, TSUJIMURA K, KONDO T, NEMOTO M, YAMANAKA T, SUGIURA T, KATO T, MAEDA K, MATSUMURA T. Mitigation of Pyrexia by a Th-1-Biased IgG Subclass Response after Infection with Equine Herpesvirus Type 1 in Horses Pre-Immunized with Inactivated Vaccine. J Vet Med Sci 2012; 74:791-5. [DOI: 10.1292/jvms.11-0449] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022] Open
Affiliation(s)
- Hiroshi BANNAI
- Epizootic Research Center, Equine Research Institute, Japan Racing Association, 1400-4 Shiba, Shimotsuke, Tochigi 329-0412, Japan
| | - Koji TSUJIMURA
- Epizootic Research Center, Equine Research Institute, Japan Racing Association, 1400-4 Shiba, Shimotsuke, Tochigi 329-0412, Japan
| | - Takashi KONDO
- Epizootic Research Center, Equine Research Institute, Japan Racing Association, 1400-4 Shiba, Shimotsuke, Tochigi 329-0412, Japan
| | - Manabu NEMOTO
- Epizootic Research Center, Equine Research Institute, Japan Racing Association, 1400-4 Shiba, Shimotsuke, Tochigi 329-0412, Japan
| | - Takashi YAMANAKA
- Epizootic Research Center, Equine Research Institute, Japan Racing Association, 1400-4 Shiba, Shimotsuke, Tochigi 329-0412, Japan
| | - Takeo SUGIURA
- Epizootic Research Center, Equine Research Institute, Japan Racing Association, 1400-4 Shiba, Shimotsuke, Tochigi 329-0412, Japan
| | - Tomohiro KATO
- Racehorse Clinic, Ritto Training Center, Japan Racing Association, 1028 Misono, Ritto, Shiga 520-3085, Japan
| | - Ken MAEDA
- Department of Veterinary Microbiology, Faculty of Agriculture, Yamaguchi University, 1677-1 Yoshida, Yamaguchi 753-8515, Japan
| | - Tomio MATSUMURA
- Epizootic Research Center, Equine Research Institute, Japan Racing Association, 1400-4 Shiba, Shimotsuke, Tochigi 329-0412, Japan
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Protective effects of passively transferred merozoite-specific antibodies against Theileria equi in horses with severe combined immunodeficiency. CLINICAL AND VACCINE IMMUNOLOGY : CVI 2011; 19:100-4. [PMID: 22038847 DOI: 10.1128/cvi.05301-11] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
Abstract
Theileria equi immune plasma was infused into young horses (foals) with severe combined immunodeficiency. Although all foals became infected following intravenous challenge with homologous T. equi merozoite stabilate, delayed time to peak parasitemia occurred. Protective effects were associated with a predominance of passively transferred merozoite-specific IgG3.
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21
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BANNAI H, TSUJIMURA K, KONDO T, NEMOTO M, YAMANAKA T, SUGIURA T, MAEDA K, MATSUMURA T. Induction of a Th-1-Biased IgG Subclass Response against Equine Herpesvirus Type 1 in Horses Previously Infected with Type 4 Virus. J Vet Med Sci 2011; 73:535-9. [DOI: 10.1292/jvms.10-0456] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022] Open
Affiliation(s)
- Hiroshi BANNAI
- Epizootic Research Center, Equine Research Institute, Japan Racing Association
| | - Koji TSUJIMURA
- Epizootic Research Center, Equine Research Institute, Japan Racing Association
| | - Takashi KONDO
- Epizootic Research Center, Equine Research Institute, Japan Racing Association
| | - Manabu NEMOTO
- Epizootic Research Center, Equine Research Institute, Japan Racing Association
| | - Takashi YAMANAKA
- Epizootic Research Center, Equine Research Institute, Japan Racing Association
| | - Takeo SUGIURA
- Epizootic Research Center, Equine Research Institute, Japan Racing Association
| | - Ken MAEDA
- Department of Veterinary Microbiology, Faculty of Agriculture, Yamaguchi University
| | - Tomio MATSUMURA
- Epizootic Research Center, Equine Research Institute, Japan Racing Association
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Maghraby S, . KHS, . HZ, . MES. In vivo the Immunological Effects of Fasciola gigantica Worms Homogenate Mixed with Saponin on Mice Infected with Schistosoma mansoni. JOURNAL OF MEDICAL SCIENCES 2007. [DOI: 10.3923/jms.2007.724.731] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/15/2022] Open
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23
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Jacks S, Giguère S, Crawford PC, Castleman WL. Experimental infection of neonatal foals with Rhodococcus equi triggers adult-like gamma interferon induction. CLINICAL AND VACCINE IMMUNOLOGY : CVI 2007; 14:669-77. [PMID: 17409222 PMCID: PMC1951072 DOI: 10.1128/cvi.00042-07] [Citation(s) in RCA: 45] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
Abstract
Rhodococcus equi is a facultative intracellular pathogen that causes pneumonia in young foals but does not induce disease in immunocompetent adult horses. Clearance of R. equi depends mainly on gamma interferon (IFN-gamma) production by T lymphocytes, whereas the predominance of interleukin 4 (IL-4) is detrimental. Young foals, like neonates of many other species, are generally deficient in the ability to produce IFN-gamma. The objective of this study was to compare the cytokine profiles, as well as cell-mediated and antibody responses, of young foals to those of adult horses following intrabronchial challenge with R. equi. The lymphoproliferative responses of bronchial lymph node (BLN) cells to concanavalin A were significantly higher in foals than in adult horses. In contrast, adult horses had significantly higher lymphoproliferative responses to R. equi antigens than did foals. Infected foals had significantly lower IL-4 mRNA expression but significantly higher IFN-gamma expression and IFN-gamma/IL-4 ratio in R. equi-stimulated BLN lymphocytes than did infected adults. Infection with R. equi in foals resulted in a significant increase in the percentage of T lymphocytes and CD4(+) T lymphocytes in bronchoalveolar lavage fluid in association with a significant decrease in the percentage of these cell populations in BLNs. Infection of foals also resulted in a marked increase in serum immunoglobulin Ga (IgGa) and IgGb levels, resulting in concentrations in serum that were significantly higher than those of adult horses. This study demonstrates that the immune response to R. equi in foals is not biased toward IL-4 and is characterized by the predominant induction of IFN-gamma.
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Affiliation(s)
- Stephanie Jacks
- Department of Large Animal Clinical Sciences, College of Veterinary Medicine, University of Florida, P.O. Box 100136, 2015 S.W. 16th Ave., Gainesville, FL 32610, USA
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