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Tuo W, Feng X, Cao L, Vinyard B, Dubey JP, Fetterer R, Jenkins M. Vaccination with Neospora caninum-cyclophilin and -profilin confers partial protection against experimental neosporosis-induced abortion in sheep. Vaccine 2021; 39:4534-4544. [PMID: 34176703 DOI: 10.1016/j.vaccine.2021.06.032] [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: 03/05/2021] [Revised: 06/02/2021] [Accepted: 06/12/2021] [Indexed: 11/16/2022]
Abstract
The purpose of this study was to evaluate the protective efficacy of a vaccine consisting of recombinant Neospora caninum-cyclophilin (NcCyP) and -profilin (NcPro) in sheep. At 42 d and 21 d prior to mating, adult Dorset ewes were immunized with the rNcCyP-rNcPro vaccine (Group 1) or co-purifying non-recombinant (NR) control vaccine (Group 2). At 90 days post-mating, all immunized ewes and were challenged by intravenous injection with 106Nesopora caninum Illinois tachyzoites (NcTZ). Significant protection (P < 0.05) was observed in Group 1 with 9 out of 13 ewes giving birth to live-born lambs (69.2%), whereas all Group 2 ewes aborted (6/6). Neospora caninum was detected by PCR in both fetal and placental tissues from all Group 2 aborting ewes and in the placental tissues of Group 1 aborting ewes. In contrast, tissues and placentas of Group 1 live-born lambs were Neospora DNA-negative. Immunoreactive Neospora antigens were demonstrated in placentas associated with abortions, but not in tissues of aborted fetuses or those of the live-born lambs and their associated placentas. Anti-NcCyP and anti-NcPro titers were high in sera from Group 1 ewes and were further boosted by challenge infection, resulting in long-lasting (≥14.5 mos.) elevated titers. Lambs born to Group 1 ewes also had high NcCyP and NcPro titers in pre-colostrum sera. Immunofluorescence staining (IFA) of NcTZ with Group 1 post-immunization sera revealed both surface and internal TZ staining, a pattern consistent with that observed with rabbit sera to rNcCyP or rNcPro. Infection of NR-vaccinated ewes produced high but transient anti-NcCyP and anti-NcPro Ab titers. The results indicate that the NcCyP-NcPro vaccine elicited strong anti-N. caninum responses and conferred significant protection against abortion and transplacental transmission of N. caninum TZ in sheep.
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Affiliation(s)
- Wenbin Tuo
- Animal Parasitic Diseases Laboratory, Beltsville Agricultural Research Center, Agricultural Research Service, USDA, Beltsville, MD 20705, United States
| | - Xiaosheng Feng
- College of Veterinary Medicine, Jilin University, Changchun, China
| | - Lili Cao
- Academy of Animal Sciences and Technology, Changchun, China
| | | | - J P Dubey
- Animal Parasitic Diseases Laboratory, Beltsville Agricultural Research Center, Agricultural Research Service, USDA, Beltsville, MD 20705, United States
| | - Raymond Fetterer
- Animal Parasitic Diseases Laboratory, Beltsville Agricultural Research Center, Agricultural Research Service, USDA, Beltsville, MD 20705, United States
| | - Mark Jenkins
- Animal Parasitic Diseases Laboratory, Beltsville Agricultural Research Center, Agricultural Research Service, USDA, Beltsville, MD 20705, United States.
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Amini L, Namavari M, Khodakaram-Tafti A, Divar MR, Hosseini SMH. The evaluation of attenuated Neospora caninum by long-term passages on murine macrophage cell line in prevention of vertical transmission in mice. Vet Parasitol 2020; 283:109171. [PMID: 32623187 DOI: 10.1016/j.vetpar.2020.109171] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/24/2019] [Revised: 06/15/2020] [Accepted: 06/16/2020] [Indexed: 11/16/2022]
Abstract
To date, there is no effective vaccine to prevent abortion or vertical transmission associated with neosporosis in cattle. In the present study, the efficacy of a live experimental vaccine of Neospora caninum attenuated (NCa) by long-term serial passages on a murine macrophage cell line was evaluated in the prevention of vertical transmission and abortion in the mouse model. Forty non-pregnant mice were randomly divided into four equal groups including non-immunized/challenged (injected with PBS); positive control (inoculated with un-attenuated NC-1 tachyzoites); immunized/challenged (inoculated with NCa attenuated strain) and immunized/non-challenged or vaccinated (inoculated with NCa) groups. Following pregnancy synchronization, both the immunized and control mice were challenged with virulent live NC-1 tachyzoites (2.5 × 106) in the mid-pregnancy stage. The number of abortions and post-natal pup mortalities was recorded. Serological, molecular, and histopathologic examinations were employed to evaluate the efficacy of the vaccine and the vertical transmission rates. Results indicated that the live attenuated N. caninum strain (NCa) could significantly reduce the risk of abnormal parturitions and fetal mortality in the vaccinated group (20 %) compared to the non-immunized/challenged group (80 %). Also, the NCa strain reduced the lesion score in the brain of the offspring (0.3 vs 1.9) compared to the non-immunized/challenged group (P < 0.05). The molecular assay showed a decrease in the parasite DNA detection rates from 83 % and 77 % in the non-immunized/challenged group to 27 % and 0 % in the vaccine group in the brain and liver tissues, respectively. While in the immunized/non-challenged group no parasite DNA was detected in the brain tissue samples of the pups. Serological analyses showed that NCa strain was able to stimulate the humoral immunity and create effective protection against neosporosis with a moderate systemic IFN-γ response. In conclusion, the NCa strain could significantly (P < 0.05) reduce the risk of vertical transmission and proved to be a safe vaccine while conferring significant levels of protection in the laboratory mice.
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Affiliation(s)
- Laleh Amini
- Department of Pathology, School of Veterinary Medicine, Shiraz University, Shiraz, Iran
| | - Mehdi Namavari
- Shiraz Branch, Razi Vaccine and Serum Research Institute, Agricultural Research, Education and Extension Organization (AREEO), Shiraz, Iran.
| | | | - Mohammad Reza Divar
- Department of Clinical Sciences, School of Veterinary Medicine, Shiraz University, Shiraz, Iran
| | - Seyed Mohammad Hossein Hosseini
- Shiraz Branch, Razi Vaccine and Serum Research Institute, Agricultural Research, Education and Extension Organization (AREEO), Shiraz, Iran
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Horcajo P, Regidor-Cerrillo J, Aguado-Martínez A, Hemphill A, Ortega-Mora LM. Vaccines for bovine neosporosis: current status and key aspects for development. Parasite Immunol 2016; 38:709-723. [DOI: 10.1111/pim.12342] [Citation(s) in RCA: 36] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/15/2016] [Accepted: 06/06/2016] [Indexed: 12/01/2022]
Affiliation(s)
- P. Horcajo
- SALUVET; Animal Health Department; Faculty of Veterinary Sciences; Complutense University of Madrid; Madrid Spain
| | - J. Regidor-Cerrillo
- SALUVET; Animal Health Department; Faculty of Veterinary Sciences; Complutense University of Madrid; Madrid Spain
| | - A. Aguado-Martínez
- Institute of Parasitology; Vetsuisse Faculty; University of Bern; Bern Switzerland
| | - A. Hemphill
- Institute of Parasitology; Vetsuisse Faculty; University of Bern; Bern Switzerland
| | - L. M. Ortega-Mora
- SALUVET; Animal Health Department; Faculty of Veterinary Sciences; Complutense University of Madrid; Madrid Spain
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Approaches for the vaccination and treatment of Neospora caninum infections in mice and ruminant models. Parasitology 2015; 143:245-59. [PMID: 26626124 DOI: 10.1017/s0031182015001596] [Citation(s) in RCA: 34] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/04/2023]
Abstract
Neospora caninum is a leading cause of abortion in cattle, and is thus an important veterinary health problem of high economic significance. Vaccination has been considered a viable strategy to prevent bovine neosporosis. Different approaches have been investigated, and to date the most promising results have been achieved with live-attenuated vaccines. Subunit vaccines have also been studied, and most of them represented components that are functionally involved in (i) the physical interaction between the parasite and its host cell during invasion or (ii) tachyzoite-to-bradyzoite stage conversion. Drugs have been considered as an option to limit the effects of vertical transmission of N. caninum. Promising results with a small panel of compounds in small laboratory animal models indicate the potential value of a chemotherapeutical approach for the prevention of neosporosis in ruminants. For both, vaccines and drugs, the key for success in preventing vertical transmission lies in the application of bioactive compounds that limit parasite proliferation and dissemination, without endangering the developing fetus not only during an exogenous acute infection but also during recrudescence of a chronic infection. In this review, the current status of vaccine and drug development is presented and novel strategies against neosporosis are discussed.
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Arranz-Solís D, Benavides J, Regidor-Cerrillo J, Fuertes M, Ferre I, Ferreras MDC, Collantes-Fernández E, Hemphill A, Pérez V, Ortega-Mora LM. Influence of the gestational stage on the clinical course, lesional development and parasite distribution in experimental ovine neosporosis. Vet Res 2015; 46:19. [PMID: 25884945 PMCID: PMC4346111 DOI: 10.1186/s13567-014-0139-y] [Citation(s) in RCA: 36] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/04/2014] [Accepted: 12/15/2014] [Indexed: 11/10/2022] Open
Abstract
Neospora caninum is considered one of the main causes of abortion in cattle, yet recent studies have also emphasised its relevance as an abortifacient in small ruminants. In order to gain deeper insight into the pathogenesis of ovine neosporosis, pregnant ewes were intravenously inoculated with 106 tachyzoites of the Nc-Spain7 isolate at days 40, 90 or 120 of gestation. Infection during the first term resulted in the death of all foetuses between days 19 and 21 post-infection, showing mainly necrotic lesions in foetal liver and the highest parasite DNA detection and burden in both placenta and foetal viscera. After infection at day 90, foetal death was also detected in all ewes, although later (34–48 days post-infection). In this group, lesions were mainly inflammatory. Foetal livers showed the lowest frequency of lesions, as well as the lowest parasite detection and burden. All ewes infected at day 120 delivered viable lambs, although 3 out of 9 showed weakness and recumbency. Neospora DNA was detected in all lambs but one, and parasite burden was similar to that observed in day 90 group. Lesions in this group showed more conspicuous infiltration of inflammatory cells and higher frequency in foetal brain and muscle when compared to both previous groups. These results highlight the crucial role that the stage of gestation plays on the course of ovine neosporosis, similar to that reported in bovine neosporosis, and open the doors to consider sheep as a valid model for exogenous transplacental transmission for ruminant neosporosis.
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Affiliation(s)
- David Arranz-Solís
- SALUVET, Animal Health Department, Faculty of Veterinary Sciences, Complutense University of Madrid, Ciudad Universitaria s/n, 28040, Madrid, Spain.
| | - Julio Benavides
- Livestock Health and Production Institute (ULE-CSIC), 24346, León, Spain.
| | - Javier Regidor-Cerrillo
- SALUVET, Animal Health Department, Faculty of Veterinary Sciences, Complutense University of Madrid, Ciudad Universitaria s/n, 28040, Madrid, Spain.
| | - Miguel Fuertes
- Livestock Health and Production Institute (ULE-CSIC), 24346, León, Spain.
| | - Ignacio Ferre
- SALUVET, Animal Health Department, Faculty of Veterinary Sciences, Complutense University of Madrid, Ciudad Universitaria s/n, 28040, Madrid, Spain.
| | | | - Esther Collantes-Fernández
- SALUVET, Animal Health Department, Faculty of Veterinary Sciences, Complutense University of Madrid, Ciudad Universitaria s/n, 28040, Madrid, Spain.
| | - Andrew Hemphill
- Institute of Parasitology, Vetsuisse Faculty, University of Bern, CH-3012, Bern, Switzerland.
| | - Valentín Pérez
- Livestock Health and Production Institute (ULE-CSIC), 24346, León, Spain.
| | - Luis Miguel Ortega-Mora
- SALUVET, Animal Health Department, Faculty of Veterinary Sciences, Complutense University of Madrid, Ciudad Universitaria s/n, 28040, Madrid, Spain.
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Experimental ruminant models for bovine neosporosis: what is known and what is needed. Parasitology 2014; 141:1471-88. [PMID: 24926962 DOI: 10.1017/s0031182014000638] [Citation(s) in RCA: 30] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/07/2022]
Abstract
At present, bovine neosporosis is an important worldwide concern because of its wide geographic distribution and economic impact. Abortion is the main clinical sign of bovine neosporosis in both dairy and beef cattle. Ruminant challenge models are critical to evaluate potential vaccine candidates to help tackle bovine neosporosis and to study pathogenesis and host responses to infection. Several research groups have developed ruminant models of Neospora caninum infection independently of others, resulting in a high degree of variability due to the use of different species of animals, breeds, strains/isolates of N. caninum, doses, routes and times of inoculation. Standardization is greatly needed to advance research in a more collaborative, timely and efficient manner. In the absence of widely accepted international guidelines, this manuscript serves to summarize and discuss the different models and parameters currently in use. Parameters essential for the development of non-pregnant and pregnant ruminant models are outlined and the main knowledge gaps are identified. This information could act as the basis to develop a consensus for international standard guidelines for ruminant models of neosporosis that would be helpful for researchers in this field worldwide.
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Monney T, Hemphill A. Vaccines against neosporosis: what can we learn from the past studies? Exp Parasitol 2014; 140:52-70. [PMID: 24602874 DOI: 10.1016/j.exppara.2014.02.015] [Citation(s) in RCA: 51] [Impact Index Per Article: 5.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/24/2013] [Revised: 02/09/2014] [Accepted: 02/18/2014] [Indexed: 10/25/2022]
Abstract
Neospora caninum is an intracellular apicomplexan parasite, which is a leading cause of abortion in cattle; thus neosporosis represents an important veterinary health problem and is of high economic significance. The parasite can infect cattle via trans-placental transmission from an infected cow to its fetus (vertical transmission), or through the oral route via ingestion of food or water contaminated with oocysts that were previously shed with the feces of a canid definitive host (horizontal transmission). Although vaccination was considered a rational strategy to prevent bovine neosporosis, the only commercialized vaccine (Neoguard®) produced ambiguous results with relatively low efficacy, and was recently removed from the market. Therefore, there is a need to develop an efficient vaccine capable of preventing both, the horizontal transmission through infected food or water to a naïve animal as well as the vertical transmission from infected but clinically asymptomatic dams to the fetus. Different vaccine strategies have been investigated, including the use of live attenuated vaccines, killed parasite lysates, total antigens or antigen fractions from killed parasites, and subunit vaccines. The vast majority of experimental studies were performed in mice, and to a certain extent in gerbils, but there is also a large number of investigations that were conducted in cattle and sheep. However, it is difficult to directly compare these studies due to the high variability of the parameters employed. In this review, we will summarize the recent advances made in vaccine development against N. caninum in cattle and in mice and highlight the most important factors, which are likely to influence the degree of protection mediated by vaccination.
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Affiliation(s)
- Thierry Monney
- Institute of Parasitology, Vetsuisse Faculty, University of Berne, Länggass-Strasse 122, CH-3012 Berne, Switzerland
| | - Andrew Hemphill
- Institute of Parasitology, Vetsuisse Faculty, University of Berne, Länggass-Strasse 122, CH-3012 Berne, Switzerland.
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Monney T, Debache K, Hemphill A. Vaccines against a Major Cause of Abortion in Cattle, Neospora caninum Infection. Animals (Basel) 2011; 1:306-25. [PMID: 26486502 PMCID: PMC4513463 DOI: 10.3390/ani1030306] [Citation(s) in RCA: 32] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/28/2011] [Revised: 08/30/2011] [Accepted: 09/06/2011] [Indexed: 01/09/2023] Open
Abstract
Simple Summary We review the efforts to develop a vaccine against neosporosis, caused by the apicomplexan parasite Neospora caninum. Vertical transmission is the main mode of infection, and can lead to stillbirth, abortion, or birth of weak calves. We provide information on the biology of Neospora caninum and on the disease caused by this parasite, and summarize the current understanding on how the host deals with infection. We review studies on live- and subunit-vaccines, and demonstrate advantages and setbacks in the use of small laboratory animal models in investigations on a disease with high relevance in cattle. Abstract Neosporosis, caused by the apicomplexan parasite Neospora caninum, represents one of the economically most important causes of abortion in cattle. During pregnancy, the parasite infects the placental tissue and the fetus, which can lead to stillbirth, abortion, or birth of weak calves. Alternatively, calves are born without clinical symptoms, but they can carry over the parasite to the next generation. In addition, N. caninum causes neuromuscular disease in dogs. The economic importance of neosporosis has prompted researchers to invest in the development of measures to prevent infection of cattle by vaccination. A good vaccine must stimulate protective cellular immune responses as well as antibody responses at mucosal sites and, systemically, must activate T-helper cells to produce relevant cytokines, and must elicit specific antibodies that aid in limiting parasite proliferation, e.g., by interference with host cell invasion, activation of complement, and/or opsonization of parasites to have them killed by macrophages. Different types of vaccines have been investigated, either in bovines or in the mouse model. These include live vaccines such as naturally less virulent isolates of N. caninum, attenuated strains generated by irradiation or chemical means, or genetically modified transgenic strains. Live vaccines were shown to be very effective; however, there are serious disadvantages in terms of safety, costs of production, and stability of the final product. Subunit vaccines have been intensively studied, as they would have clear advantages such as reduced costs in production, processing and storage, increased stability and shelf life. The parasite antigens involved in adhesion and invasion of host cells, such as surface constituents, microneme-, rhoptry- and dense granule-components represent interesting targets. Subunit vaccines have been applied as bacterially expressed recombinant antigens or as DNA vaccines. Besides monovalent vaccines also polyvalent combinations of different antigens have been used, providing increased protection. Vaccines have been combined with immunostimulating carriers and, more recently, chimeric vaccines, incorporating immuno-relevant domains of several antigens into a single protein, have been developed.
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Affiliation(s)
- Thierry Monney
- Institute of Parasitology, Vetsuisse Faculty, University of Berne, Länggass-Strasse 122, CH-3012 Berne, Switzerland.
| | - Karim Debache
- Institute of Parasitology, Vetsuisse Faculty, University of Berne, Länggass-Strasse 122, CH-3012 Berne, Switzerland.
| | - Andrew Hemphill
- Institute of Parasitology, Vetsuisse Faculty, University of Berne, Länggass-Strasse 122, CH-3012 Berne, Switzerland.
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Tuo W, Zhao Y, Zhu D, Jenkins MC. Immunization of female BALB/c mice with Neospora cyclophilin and/or NcSRS2 elicits specific antibody response and prevents against challenge infection by Neospora caninum. Vaccine 2011; 29:2392-9. [PMID: 21281689 DOI: 10.1016/j.vaccine.2011.01.041] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/09/2010] [Revised: 01/14/2011] [Accepted: 01/14/2011] [Indexed: 11/17/2022]
Abstract
Neospora caninum is the causal agent of bovine neosporosis which results in high levels of abortion. The present study determined the protective efficacy of two Neospora antigens--Neospora cyclophilin (NcCyP) and NcSRS2. The ability of native NcCyP to upregulate mouse IFN-γ was also confirmed in this study. Recombinant NcCyP or NcSRS2 were tested either alone or in combination and formulated with adjuvant ImmuMax-SR and CpG. Female BALB/c mice (n=15) of 10-12 weeks of age were immunized s.c. twice over a 2-week interval with vaccines containing either NcCyP (20 μg/dose) alone, NcSRS2 (20 μg/dose) alone, NcCyP plus NcSRS2, or non-recombinant bacterial antigen (NR) in 2 separate trials. All mice were challenge-infected 3 weeks following the booster immunization and necropsied 3 weeks after the challenge infection. Brain and serum were collected and Nc-specific DNA sequence in brain tissue and antibodies in serum were analyzed by PCR or ELISA/Western blotting. Results showed that mice vaccinated with rNcCyP, rNcSRS2, or both rNcCyP and rNcSRS2 responded with high levels of NcCyP or NcSRS2 specific antibodies. Overall, mice received vaccines formulated with either rNcCyP or rNcCyP and rNcSRS2 had a higher (p<0.01) percent protection when compared to the mock- or non-vaccinated mice. The group immunized with rNcSRS2 alone exhibited slightly lower levels of protection, which was higher (p<0.05) than that of the non-vaccinated group but did not differ (p=0.06) from that of the mock-vaccinated group. The results of the present study indicate that NcCyP is a highly efficacious vaccine candidate which may be useful in protection against Neospora infection.
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Affiliation(s)
- Wenbin Tuo
- Animal Parasitic Diseases Laboratory, Beltsville Agricultural Research Center, USDA/ARS, Beltsville, MD 20705, USA.
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Jenkins MC, Tuo W, Feng X, Cao L, Murphy C, Fetterer R. Neospora caninum: cloning and expression of a gene coding for cytokine-inducing profilin. Exp Parasitol 2010; 125:357-62. [PMID: 20211619 DOI: 10.1016/j.exppara.2010.03.001] [Citation(s) in RCA: 20] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/07/2009] [Revised: 02/26/2010] [Accepted: 03/01/2010] [Indexed: 11/27/2022]
Abstract
Profilins are actin-binding proteins that in Toxoplasma gondii stimulate innate immunity in mice by binding Toll-like receptors (TLR) on dendritic cells (DC) leading to release of inflammatory cytokines, primarily IL-12 and IFN-gamma. The purpose of the present study was to characterize Neospora caninum profilin, termed NcProfilin. Recombinant NcProfilin was purified by affinity chromatography, and used to prepare specific antisera to allow characterization of native NcProfilin antigen in N. caninum tachyzoites. By immunoblotting, recombinant NcProfilin is 22kDa, and is similar in size to the respective 22kDa native protein. Immunofluorescence and immunoelectron microscopy localized native NcProfilin to the apical end of N. caninum tachyzoites. Incubation of recombinant NcProfilin with spleen cells from BALB/c mice induced release of IFN-gamma. Also, injection of BALB/c mice with purified rNcProfilin elicited a strong IFN-gamma and IL-12 responses at 6 and 24h after injection indicating that NcProfilin may be an important protein in regulation of cytokine responses to N. caninum.
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Affiliation(s)
- Mark C Jenkins
- Animal Parasitic Diseases Laboratory, Agricultural Research Service, U.S. Department of Agriculture, Beltsville, MD 20705, USA.
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Weston J, Howe L, Collett M, Pattison R, Williamson N, West D, Pomroy W, Syed-Hussain S, Morris S, Kenyon P. Dose-titration challenge of young pregnant sheep with Neospora caninum tachyzoites. Vet Parasitol 2009; 164:183-91. [DOI: 10.1016/j.vetpar.2009.05.013] [Citation(s) in RCA: 22] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/03/2008] [Revised: 05/04/2009] [Accepted: 05/11/2009] [Indexed: 11/25/2022]
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Reichel MP, Ellis JT. Neospora caninum--how close are we to development of an efficacious vaccine that prevents abortion in cattle? Int J Parasitol 2009; 39:1173-87. [PMID: 19497326 DOI: 10.1016/j.ijpara.2009.05.007] [Citation(s) in RCA: 76] [Impact Index Per Article: 5.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/14/2009] [Revised: 05/19/2009] [Accepted: 05/20/2009] [Indexed: 10/20/2022]
Abstract
Neospora caninum is a protozoan parasite that causes abortion in cattle around the world. Although the clinical signs of disease in both dogs and cattle have now been recognised for over 20years, treatment and control options are still limited, despite the availability of a commercial vaccine in some countries of the world. The case for an efficacious vaccine has not been convincingly waged by farmers, veterinarians and other members of the agricultural and rural communities. In recent times, however, economic modelling has been used to estimate the industry losses due to Neospora-associated abortion, providing, in turn, the business case for forms of control for this parasite, including the development of vaccines. In this review, we document progress in all areas of the vaccine development pipeline, including live, killed and recombinant forms and the animal models available for vaccine evaluation. In addition, we summarise the main outcomes on the economics of Neospora control and suggest that the current boom in the global dairy industry increases the specific need for a vaccine against N. caninum-associated abortion.
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Affiliation(s)
- Michael P Reichel
- Department of Medical and Molecular Biosciences, University of Technology, Sydney, P.O. Box 123, Broadway, NSW 2007, Australia
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Debache K, Guionaud C, Alaeddine F, Mevissen M, Hemphill A. Vaccination of mice with recombinant NcROP2 antigen reduces mortality and cerebral infection in mice infected with Neospora caninum tachyzoites. Int J Parasitol 2008; 38:1455-63. [PMID: 18495126 DOI: 10.1016/j.ijpara.2008.04.001] [Citation(s) in RCA: 52] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/25/2008] [Revised: 03/04/2008] [Accepted: 04/06/2008] [Indexed: 10/22/2022]
Abstract
Rhoptry antigens are involved in a variety of cellular functions related to host cell invasion, formation of the parasitophorous vacuole and parasite-host cell interplay. The cDNA sequence of one of these antigens, NcROP2 was identified from Neospora caninum expressed sequence tags (ESTs), amplified by reverse transcription-PCR, expressed in Escherichia coli as a (His)(6)-tagged recombinant protein (recNcROP2) and purified over Ni(2+)-affinity chromatography. Both recNcROP2 and antibodies directed against recNcROP2 had a negative impact on N. caninum tachyzoite host cell invasion in vitro, indicating that this protein participates in the host cell entry process. Subsequently, the protective efficacy of NcROP2 as a potential vaccine candidate was evaluated in a C57BL/6 mouse cerebral disease model. Mice were vaccinated three times at 2-week intervals with recNcROP2 emulsified either in Freund's incomplete adjuvants (FIA) or saponin, and control groups were treated with adjuvants alone (adjuvants control) or PBS (infection control). Subsequently, mice were challenged with 2x10(6)N. caninum tachyzoites. Nine mice, all belonging to the infection control or adjuvants control groups, exhibited clinical signs of cerebral neosporosis and succumbed to infection, whilst no clinical signs were noted for recNcROP2-vaccinated mice. For all other animals, the experiment was terminated 35 days p.i. Cerebral parasite burdens were assessed by quantitative PCR in all mice, and were revealed to be significantly reduced in the recNcROP2-vaccinated mice. ELISA of sera revealed IgG1 to be elevated in recNcROP2-saponin vaccinated mice, whilst IgG2a was higher in recNcROP2-FIA vaccinated animals. This shows that, depending on the adjuvants used, vaccination with NcROP2 induces a protective Th-1- or Th-2-biased immune response against experimental N. caninum infection.
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Affiliation(s)
- Karim Debache
- Institute of Parasitology, Vetsuisse Faculty, University of Berne, Länggass-Strasse 122, CH-3012 Berne, Switzerland.
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Reichel M, Ross G, McAllister M. Evaluation of an enzyme-linked immunosorbent assay for the serological diagnosis of Neospora caninum infection in sheep and determination of the apparent prevalence of infection in New Zealand. Vet Parasitol 2008; 151:323-6. [DOI: 10.1016/j.vetpar.2007.11.002] [Citation(s) in RCA: 25] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/19/2007] [Revised: 11/01/2007] [Accepted: 11/05/2007] [Indexed: 12/01/2022]
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Williams DJL, Trees AJ. Review Article. Protecting babies: vaccine strategies to prevent foetopathy in Neospora caninum-infected cattle. Parasite Immunol 2006; 28:61-7. [PMID: 16441503 DOI: 10.1111/j.1365-3024.2005.00809.x] [Citation(s) in RCA: 45] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
Neospora caninum is an apicomplexan protozoan parasite that is a significant infectious abortifacient agent in cattle. Despite the fact that it is a member of a well described taxonomic group, it is a relatively newly discovered parasite and its biology is not yet fully understood. Cattle become infected either congenitally via transplacental transmission or post-natally by ingesting oocysts derived from the definitive host; dogs and coyotes are the only definitive hosts that have been described to date. It is not known which of these two forms of transmission occurs most frequently and which is the most likely to result in abortion; there are no drugs available to treat infected cattle, so current control strategies rely on prevention of infection by management methods and strict hygiene; an effective vaccine would be a great advantage in its control. Neospora caninum is an economically important veterinary pathogen, but we can also draw analogies between its foetopathic effects and those of human pathogens such as Toxoplasma gondii, Chlamydophila abortus and Plasmodium falciparum. Understanding the immune response and the materno-foetal relationship in N. caninum-infected cattle may help us to design vaccination strategies, not only for neosporosis but also for other foetopathic agents.
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Affiliation(s)
- D J L Williams
- Veterinary Parasitology, Liverpool School of Tropical Medicine, Pembroke Place, Liverpool, UK.
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Haldorson GJ, Mathison BA, Wenberg K, Conrad PA, Dubey JP, Trees AJ, Yamane I, Baszler TV. Immunization with native surface protein NcSRS2 induces a Th2 immune response and reduces congenital Neospora caninum transmission in mice. Int J Parasitol 2005; 35:1407-15. [PMID: 16051244 DOI: 10.1016/j.ijpara.2005.05.013] [Citation(s) in RCA: 55] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/11/2005] [Revised: 05/20/2005] [Accepted: 05/20/2005] [Indexed: 11/25/2022]
Abstract
NcSRS2, a tachyzoite surface protein of Neospora caninum, is an immunodominant protein with respect to induction of antibody production and has a role in attachment and invasion of host cells. Native NcSRS2 was isolated from whole tachyzoite lysate antigen by affinity chromatography using NcSRS2 specific monoclonal antibody and used to immunize BALB/c mice in a congenital transmission study. NcSRS2 was a highly conserved protein as indicated by comparison of deduced amino acid sequence obtained from NcSRS2 gene sequences of 10 geographically distinct N. caninum isolates. Mice immunized with purified native NcSRS2 produced antigen-specific antibody, primarily of IgG 1 subtype. Following challenge during gestation with 10(7) tachyzoites, immunized mice had a statistically significant decreased frequency of congenital transmission compared to non-immunized mice (P<or=0.05) or mice inoculated with adjuvant alone (P<or=0.01). Decreased congenital transmission among immunized mice correlated with a predominately Th2 immune response compared to non-immunized mice as indicated by an increased ratio of interleukin 4 (IL-4) to interferon gamma (IFN-gamma) secretion from antigen-stimulated splenocytes. The results provide a rationale for NcSRS2 as a candidate subunit vaccine antigen for reduction of N. caninum congenital transmission. Furthermore, the studies suggest that a Th2 immune response, if directed against an appropriate antigen, may induce protection against N. caninum congenital infection in mice.
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MESH Headings
- Animals
- Antigens, Protozoan/genetics
- Antigens, Protozoan/immunology
- Antigens, Protozoan/isolation & purification
- Antigens, Surface/genetics
- Antigens, Surface/immunology
- Antigens, Surface/isolation & purification
- Chromatography, Affinity/methods
- Coccidiosis/congenital
- Coccidiosis/immunology
- Coccidiosis/prevention & control
- Coccidiosis/transmission
- Female
- Immunization
- Infectious Disease Transmission, Vertical/prevention & control
- Interferon-gamma/biosynthesis
- Interleukin-4/biosynthesis
- Mice
- Mice, Inbred BALB C
- Molecular Sequence Data
- Neospora/immunology
- Polymerase Chain Reaction/methods
- Pregnancy
- Pregnancy Complications, Parasitic/immunology
- Pregnancy Complications, Parasitic/prevention & control
- Protozoan Proteins/genetics
- Protozoan Proteins/immunology
- Protozoan Proteins/isolation & purification
- Protozoan Vaccines/immunology
- Th2 Cells/immunology
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Affiliation(s)
- G J Haldorson
- Department of Veterinary Microbiology and Pathology, Washington State University, Bustad Hall, Pullman, WA 99164-7040, USA
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