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Potărniche AV, Czopowicz M, Szaluś-Jordanow O, Moroz A, Mickiewicz M, Witkowski L, Markowska-Daniel I, Bagnicka E, Cerbu C, Olah D, Spinu M, Kaba J. Diagnostic accuracy of three commercial immunoenzymatic assays for small ruminant lentivirus infection in goats performed on individual milk samples. Prev Vet Med 2021; 191:105347. [PMID: 33862543 DOI: 10.1016/j.prevetmed.2021.105347] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/28/2021] [Revised: 03/21/2021] [Accepted: 04/06/2021] [Indexed: 10/21/2022]
Abstract
Caprine arthritis-encephalitis (CAE) caused by small ruminant lentivirus (SRLV) infection is one of the most widespread and devastating diseases of goats. Serological methods, mainly immunoenzymatic assays (ELISA), are the mainstay of CAE diagnostics. Even though blood is still the most commonly tested material, animal welfare issues and increasing costs of veterinary service prompt the development of serological methods based on milk testing. Several different types of ELISAs for CAE are available on the market. All of them perform well on serum, however their diagnostic accuracy for testing milk has not been so far compared. Therefore, we carried out the study in 5 dairy goat herds in Poland whose previous epidemiological situation regarding CAE was known. Paired serum and milk samples were collected from all adult females (n = 420) and tested with 3 commercial ELISAs - indirect ELISA based on the whole-virus antigen (wELISA), indirect ELISA based on the recombined transmembrane and capsid protein (TM/CA-ELISA), and competitive ELISA based on the surface glycoprotein (SU-ELISA). Milk was tested as lactoserum at dilution of 1/2 in wELISA and TM/CA-ELISA, and undiluted in SU-ELISA. The true status of goats was based on the composite reference standard comprising the results of all three ELISAs done on serum and the true prevalence of SRLV infection in the herd of origin. 243 (57.9 %) goats were classified as truly positive and 177 (42.1 %) goats as truly negative. Diagnostic accuracy was evaluated using the area under the ROC curve (AUROC) as well as sensitivity (Se) and specificity (Sp) for a range of cut-off values. AUROC was 98.8 % (CI 95 %: 97.5 %, 100 %) for wELISA, 97.9 % (CI 95 %: 96.5 %, 99.2 %) for TM/CA-ELISA, and 91.7 % (CI 95 %: 88.9 %, 94.5 %) for SU-ELISA. At the cut-off values recommended by the manufacturers both indirect ELISAs were highly sensitive (89.3 % and 91.4 %, respectively) and highly specific (98.3 % and 95.5 %, respectively), whereas SU-ELISA had only moderate Se (71.2 %) at comparably high Sp (96.6 %). Nevertheless, the optimal cut-off values were lower than those recommended by manufacturers for serum - sample-to-positive control serum ratio (S/P%) of 10 % for wELISA, S/P% of 80 % for TM/CA-ELISA, and percentage inhibition of 23 % for SU-ELISA. Concluding, the study shows that wELISA and TM/CA-ELISA may be interchangeably used for testing individual goat milk samples for SRLV infection. Diagnostic sensitivity and specificity of these ELISAs appear not to be lower on milk than on serum. SU-ELISA is considerably less sensitive on milk samples than indirect ELISAs.
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Affiliation(s)
- Adrian-Valentin Potărniche
- Department of Infectious Diseases and Preventive Medicine, Faculty of Veterinary Medicine, University of Agricultural Sciences and Veterinary Medicine Cluj-Napoca, Calea Manastur 3-5, 400372, Cluj-Napoca, Romania
| | - Michał Czopowicz
- Division of Veterinary Epidemiology and Economics, Institute of Veterinary Medicine, Warsaw University of Life Sciences-SGGW, Nowoursynowska 159c, 02-776, Warsaw, Poland.
| | - Olga Szaluś-Jordanow
- Department of Small Animal Diseases with Clinic, Institute of Veterinary Medicine, Warsaw University of Life Sciences-SGGW, Nowoursynowska 159c, 02-776, Warsaw, Poland
| | - Agata Moroz
- Division of Veterinary Epidemiology and Economics, Institute of Veterinary Medicine, Warsaw University of Life Sciences-SGGW, Nowoursynowska 159c, 02-776, Warsaw, Poland
| | - Marcin Mickiewicz
- Division of Veterinary Epidemiology and Economics, Institute of Veterinary Medicine, Warsaw University of Life Sciences-SGGW, Nowoursynowska 159c, 02-776, Warsaw, Poland
| | - Lucjan Witkowski
- Division of Veterinary Epidemiology and Economics, Institute of Veterinary Medicine, Warsaw University of Life Sciences-SGGW, Nowoursynowska 159c, 02-776, Warsaw, Poland
| | - Iwona Markowska-Daniel
- Division of Veterinary Epidemiology and Economics, Institute of Veterinary Medicine, Warsaw University of Life Sciences-SGGW, Nowoursynowska 159c, 02-776, Warsaw, Poland
| | - Emilia Bagnicka
- Institute of Genetics and Animal Biotechnology, Polish Academy of Sciences, Postępu 36A, Jastrzębiec, 05-552, Magdalenka, Poland
| | - Constantin Cerbu
- Department of Infectious Diseases and Preventive Medicine, Faculty of Veterinary Medicine, University of Agricultural Sciences and Veterinary Medicine Cluj-Napoca, Calea Manastur 3-5, 400372, Cluj-Napoca, Romania
| | - Diana Olah
- Department of Infectious Diseases and Preventive Medicine, Faculty of Veterinary Medicine, University of Agricultural Sciences and Veterinary Medicine Cluj-Napoca, Calea Manastur 3-5, 400372, Cluj-Napoca, Romania
| | - Marina Spinu
- Department of Infectious Diseases and Preventive Medicine, Faculty of Veterinary Medicine, University of Agricultural Sciences and Veterinary Medicine Cluj-Napoca, Calea Manastur 3-5, 400372, Cluj-Napoca, Romania
| | - Jarosław Kaba
- Division of Veterinary Epidemiology and Economics, Institute of Veterinary Medicine, Warsaw University of Life Sciences-SGGW, Nowoursynowska 159c, 02-776, Warsaw, Poland
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2
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Adjadj NR, Vicca J, Michiels R, De Regge N. (Non-)Sense of Milk Testing in Small Ruminant Lentivirus Control Programs in Goats. Comparative Analysis of Antibody Detection and Molecular Diagnosis in Blood and Milk. Viruses 2019; 12:v12010003. [PMID: 31861451 PMCID: PMC7019267 DOI: 10.3390/v12010003] [Citation(s) in RCA: 11] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/25/2019] [Revised: 12/06/2019] [Accepted: 12/16/2019] [Indexed: 12/16/2022] Open
Abstract
Small ruminant lentivirus (SRLV) control programs are mainly based on diagnostic tests performed on blood samples collected from sheep and goats. Since blood sampling is costly and stressful for the animals, we evaluated whether milk could be used as an inexpensive and easily collectable matrix for SRLV detection. We therefore compared SRLV detection via two commercial enzyme-linked immunosorbent assays (ELISAs) and quantitative polymerase chain reaction (qPCR) in blood and corresponding milk samples from 321 goats originating from eight different SRLV-infected farms in Flanders (Belgium). The IDscreen® ELISA had a better relative sensitivity (97% vs 93%) and specificity (100% and 97%) than the Elitest® ELISA for SRLV-specific antibody detection in milk compared to serum. The higher sensitivity correlates with a 10-fold higher analytical sensitivity of the IDscreen® test. In contrast to the overall good ELISA results, qPCR on milk cell pellets lacked sensitivity (81%) and specificity (88%), compared to molecular detection in blood leucocyte pellets. Our results show that serology is more suitable than qPCR for SRLV diagnosis, and that milk may represent an interesting matrix for a preliminary evaluation of a herd’s infection status. Serum remains however the sample of choice for control programs where it is important to identify positive animals with the highest sensitivity.
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Affiliation(s)
- Nadjah Radia Adjadj
- Unit of Enzootic, Vector-Borne and Bee Diseases, Sciensano, Groeselenberg 99, 1180 Brussels, Belgium; (R.M.); (N.D.R.)
- Correspondence: ; Tel.: +32-2-379-05-61
| | - Jo Vicca
- Odisee vzw, University College KULeuven, Campus Sint-Niklaas, Hospitaalstraat 23, 9100 Sint-Niklaas, Belgium;
| | - Rodolphe Michiels
- Unit of Enzootic, Vector-Borne and Bee Diseases, Sciensano, Groeselenberg 99, 1180 Brussels, Belgium; (R.M.); (N.D.R.)
| | - Nick De Regge
- Unit of Enzootic, Vector-Borne and Bee Diseases, Sciensano, Groeselenberg 99, 1180 Brussels, Belgium; (R.M.); (N.D.R.)
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3
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Lacasta D, González J, Navarro T, Saura F, Acín C, Vasileiou N. Significance of respiratory diseases in the health management of sheep. Small Rumin Res 2019. [DOI: 10.1016/j.smallrumres.2019.03.004] [Citation(s) in RCA: 10] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
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Minguijón E, Reina R, Pérez M, Polledo L, Villoria M, Ramírez H, Leginagoikoa I, Badiola JJ, García-Marín JF, de Andrés D, Luján L, Amorena B, Juste RA. Small ruminant lentivirus infections and diseases. Vet Microbiol 2015; 181:75-89. [PMID: 26371852 DOI: 10.1016/j.vetmic.2015.08.007] [Citation(s) in RCA: 92] [Impact Index Per Article: 10.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/08/2023]
Abstract
Small ruminant lentiviruses include viruses with diverse genotypes that frequently cross the species barrier between sheep and goats and that display a great genetic variability. These characteristics stress the need to consider the whole host range and to perform local surveillance of the viruses to opt for optimum diagnostic tests, in order to establish control programmes. In the absence of effective vaccines, a comprehensive knowledge of the epidemiology of these infections is of major importance to limit their spread. This article intends to cover these aspects and to summarise information related to characteristics of the viruses, pathogenesis of the infection and description of the various syndromes produced, as well as the diagnostic tools available, the mechanisms involved in transmission of the pathogens and, finally, the control strategies that have been designed until now, with remarks on the drawbacks and the advantages of each one. We conclude that there are many variables influencing the expected cost and benefits of control programs that must be evaluated, in order to put into practice measures that might lead to control of these infections.
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Affiliation(s)
- E Minguijón
- Department of Animal Health, NEIKER-Tecnalia, Berreaga 1, 48160 Derio, Vizcaya, Spain
| | - R Reina
- Institute of Agrobiotechnology (CSIC-UPNA-Government of Navarra), Avenida de Pamplona 123, 31192 Mutilva, Spain
| | - M Pérez
- Department of Anatomy, Embryology and Genetics. University of Zaragoza, Miguel Servet 177, 50013 Zaragoza, Spain
| | - L Polledo
- Pathological Anatomy Section, Animal Health Department, Veterinary School, University of León, 24007 León, Spain
| | - M Villoria
- Department of Animal Health, NEIKER-Tecnalia, Berreaga 1, 48160 Derio, Vizcaya, Spain
| | - H Ramírez
- Facultad de Estudios Superiores Cuautitlán. UNAM. Laboratorio de Virología, Genética y Biología Molecular, Campo 4. Veterinaria.Carretera Cuautitlán-Teoloyucan, Km 2.5. San Sebastián Xhala, Cuautitlán Izcalli, CP.54714 Mexico
| | - I Leginagoikoa
- Department of Animal Health, NEIKER-Tecnalia, Berreaga 1, 48160 Derio, Vizcaya, Spain
| | - J J Badiola
- Department of Animal Pathology, University of Zaragoza, Miguel Servet 177, 50013 Zaragoza, Spain
| | - J F García-Marín
- Pathological Anatomy Section, Animal Health Department, Veterinary School, University of León, 24007 León, Spain
| | - D de Andrés
- Institute of Agrobiotechnology (CSIC-UPNA-Government of Navarra), Avenida de Pamplona 123, 31192 Mutilva, Spain
| | - L Luján
- Department of Animal Pathology, University of Zaragoza, Miguel Servet 177, 50013 Zaragoza, Spain
| | - B Amorena
- Institute of Agrobiotechnology (CSIC-UPNA-Government of Navarra), Avenida de Pamplona 123, 31192 Mutilva, Spain
| | - R A Juste
- Department of Animal Health, NEIKER-Tecnalia, Berreaga 1, 48160 Derio, Vizcaya, Spain.
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Benavides J, Fuertes M, García-Pariente C, Otaola J, Delgado L, Giraldez J, García Marín JF, Carmen Ferreras M, Pérez V. Impact of maedi-visna in intensively managed dairy sheep. Vet J 2013; 197:607-12. [PMID: 23643869 DOI: 10.1016/j.tvjl.2013.03.031] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/23/2012] [Revised: 03/19/2013] [Accepted: 03/26/2013] [Indexed: 10/26/2022]
Abstract
Maedi-visna (MV) is a slow lentiviral disease of sheep that has a significant economic impact in many sheep-producing regions although there remains a paucity of data relating to actual production losses resulting from this disease. The objective of this study was to evaluate direct losses, through death or culling, from two dairy sheep flocks with high seroprevalences of infection over a 2 year period. Maedi-visna was found, either alone or in combination with other diseases, to be the most common disease diagnosed in these sheep, and the major cause of direct animal losses in the two flocks. Moderate to severe lesions associated with MV were found in 52% and 80% of the sheep, respectively, affecting the lungs, brain and/or mammary glands. Despite the similarity of the two flocks under study in terms of breed, number of animals, geographical proximity, and inter-change of rams, a striking difference was observed regarding the clinical presentation of the disease: in one flock the respiratory form was dominant while in the other 70% of animals died or were culled because of neurological signs.
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Affiliation(s)
- Julio Benavides
- Instituto de Ganadería de Montaña (CSIC-ULE), 24346 Grulleros, León, Spain.
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6
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Brinkhof J, Houwers D, Moll L, Dercksen D, van Maanen C. Diagnostic performance of ELISA and PCR in identifying SRLV-infected sheep and goats using serum, plasma and milk samples and in early detection of infection in dairy flocks through bulk milk testing. Vet Microbiol 2010; 142:193-8. [DOI: 10.1016/j.vetmic.2009.09.060] [Citation(s) in RCA: 32] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/05/2009] [Revised: 09/16/2009] [Accepted: 09/17/2009] [Indexed: 10/20/2022]
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7
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Ramírez H, Román BS, Glaria I, Reina R, Hernández MM, de Andrés X, Crespo H, Hichou B, Cianca S, Goñi C, Grandas A, García-Pastor L, Vijil LE, Quintín F, Grilló MJ, de Andrés D, Amorena B. Antibody-based diagnosis of small ruminant lentivirus infection in seminal fluid. Theriogenology 2009; 72:1085-96. [PMID: 19729193 DOI: 10.1016/j.theriogenology.2009.06.028] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/21/2009] [Revised: 06/25/2009] [Accepted: 06/28/2009] [Indexed: 02/08/2023]
Abstract
Antibody-based diagnosis of small ruminant lentiviruses (SRLVs) has been efficiently achieved using serum and milk, but not semen, for which polymerase chain reaction (PCR) has been proposed as a confirmatory technique. This work, involving 296 ovine (Ovis aries) and caprine (Capra hircus) semen donors, investigates whether seminal fluid (SF) can be reliably used in antibody-based SRLV diagnosis. First, a gold standard was established to assess the infection status and determine the sensitivity and specificity of three commercial enzyme-linked immunosorbent assays (ELISAs) in serum testing using Western blot and PCR as confirmatory tests. For SF testing, both gold standard and serum testing results were used as reference. The performance of SF testing was affected not only by the ELISA assay sensitivity (related to antigen spectrum) compared with that of the gold standard (as it occurred in serum testing) but also by SF sample quality and SF working dilution. Nonturbid SF samples, commonly collected in artificial insemination centers (AICs), were required. Compared with serum, SF testing had a decreased sensitivity in two of the ELISA assays (with original serum working dilutions <or=1/20 in serum testing) but reached a similar sensitivity (and specificity) in the assay designed to work at the highest serum dilution (1/500). A SF concentration of about 1/2 (250-fold that used in serum testing) was found optimal in this assay, yielding highly repeatable results that were in almost perfect agreement with those of serum testing (kappa +/- SE, 0.91 +/- 0.81). Thus, SF ELISA can be reliably applied in antibody-based SRLV diagnosis. This information may be useful to control infection in AICs and animal and semen trade programs requiring health-certified quality of semen donors.
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Affiliation(s)
- H Ramírez
- Instituto de Agrobiotecnología, CSIC-Universidad Pública de Navarra-Gobierno de Navarra, 31192 Mutilva Baja, Spain
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8
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Singh I, McConnell I, Dalziel R, Blacklaws BA. Serum containing ovine IgG2 antibody specific for maedi visna virus envelope glycoprotein mediates antibody dependent cellular cytotoxicity. Vet Immunol Immunopathol 2006; 113:357-66. [PMID: 16876878 DOI: 10.1016/j.vetimm.2006.06.006] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/06/2006] [Revised: 06/12/2006] [Accepted: 06/19/2006] [Indexed: 11/25/2022]
Abstract
Antibody-dependent cell-mediated cytotoxicity (ADCC) specific for maedi visna virus (MVV) has never been described. The IgG antibody response to MVV is restricted to an IgG1 response whilst MVV specific IgG2 is never seen in persistently infected sheep. To determine whether the isotypic restriction of the antibody response is responsible for the lack of ADCC, an ADCC assay was developed using polyclonal serum raised to recombinant MVV ENV protein. Sheep immunised with a recombinant GST:SUenv fusion protein in complete Freund's adjuvant produced an antibody response which contained IgG1 and IgG2 antibodies. The activity of this serum in an ADCC assay was compared to serum from persistently infected sheep. Serum from immunised sheep mediated ADCC reactions whilst no activity was ever seen in persistently infected sheep serum. IgG2 may therefore be the possible effector isotype for ADCC reactions against MVV. Failure of the IgG2 dependent ADCC system in vivo may contribute to the persistence of MVV-infected macrophages in vivo.
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Affiliation(s)
- Inderpal Singh
- VaxDesign Corporation, 2721 Discovery Drive, Suite 400, Orlando, FL 32826, USA.
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9
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de Andrés D, Klein D, Watt NJ, Berriatua E, Torsteinsdottir S, Blacklaws BA, Harkiss GD. Diagnostic tests for small ruminant lentiviruses. Vet Microbiol 2005; 107:49-62. [PMID: 15795077 DOI: 10.1016/j.vetmic.2005.01.012] [Citation(s) in RCA: 125] [Impact Index Per Article: 6.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/13/2004] [Revised: 12/21/2004] [Accepted: 01/27/2005] [Indexed: 11/18/2022]
Abstract
Maedi visna virus and caprine arthritis encephalitis virus are closely related retroviruses that cause chronic inflammatory disease in small ruminants. The infections are characterised by insidious onset and slow progression. Diagnosis of infection is usually by serological testing. A variety of assays are available for this purpose, though the relative sensitivity and specificity of these assays has not been compared systematically. Here we review recent developments in laboratory diagnostic methods and their use in field diagnosis. The results suggest that a combination of ELISA and PCR might afford optimal detection of SRLV infection.
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Affiliation(s)
- D de Andrés
- Institute of Agrobiotechnology and Natural Resources, Pamplona, Spain
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Capucchio MT, Sanna E, Sanna MP, Farigu S, Minelli R, Guarda F. Maedi-visna virus detection in ovine third eyelids. J Comp Pathol 2003; 129:37-43. [PMID: 12859906 DOI: 10.1016/s0021-9975(02)00158-5] [Citation(s) in RCA: 18] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
Maedi-visna is a systemic disease of sheep caused by a lentivirus, maedi-visna virus (MVV), which mainly affects the lungs and central nervous system but may also affect the mammary glands, joints and other tissues. The aim of the present study was to determine whether the third eyelid was affected in cases of systemic infection. Third eyelid and lung samples from sheep naturally infected with maedi were used. Total DNA was extracted from paraffin-wax-embedded tissues, and a nested polymerase chain reaction (PCR) was performed to amplify MVV proviral DNA. The samples were also tested by in-situ PCR and immunohistochemical methods specific for the detection of MVV proviral DNA and p25, respectively. All sheep showed moderate to severe chronic lymphoproliferative inflammation in the third eyelids. Products of the expected size were obtained by PCR from both lung and third eyelid tissue. In the nictitating membrane, MVV proviral DNA was detected in situ within macrophages, and glandular, ductal and surface epithelia. Immunohistochemistry demonstrated that the infection was productive. Taken together, these results indicate that the third eyelid may represent a target for natural MVV infection and may play a role in disease transmission.
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Affiliation(s)
- M T Capucchio
- Dipartimento di Patologia Animale, Facoltà di Medicina Veterinaria, Università di Torino, Via Leonardo Da Vinci 44, 10095 Grugliasco, Turin, Italy
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11
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Contreras A, Luengo C, Sánchez A, Corrales J. The role of intramammary pathogens in dairy goats. ACTA ACUST UNITED AC 2003. [DOI: 10.1016/s0301-6226(02)00172-0] [Citation(s) in RCA: 55] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/27/2022]
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12
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Callado AKC, Castro RSD, Teixeira MFDS. Lentivírus de pequenos ruminantes (CAEV e Maedi-Visna): revisão e perspectivas. PESQUISA VETERINARIA BRASILEIRA 2001. [DOI: 10.1590/s0100-736x2001000300001] [Citation(s) in RCA: 30] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
Os lentivírus de pequenos ruminantes (SRLV), cujos protótipos são os vírus da Artrite-Encefalite Caprina (CAEV) e Maedi-Visna, são patógenos amplamente distribuidos, os quais causam doenças degenerativas progressivas lentas em caprinos e ovinos, determinando importantes perdas econômicas. Estes vírus causam infecções persistentes com período de incubação longo e causam inflamatórias e degenerativas. As lesões são induzidas em tecidos específicos do hospedeiro como articulações, pulmões, CNS e glandulas mamárias devido à replicação viral em células da linhagem monocítico-fagocitária que são as principais células-alvo. A infecção ocorre principalmente durante os primeiros meses de vida, através da ingestão de vírus no leite ou colostro de cabras ou ovelhas infectadas. A indução da resposta imunológica é variável e não protege contra a infecção. O diagnóstico é baseado primariamente na detecção de anticorpos para SRLV, geralmente por imunodifusão em gel de agar (AGID) e enzyme linked immunosorbent assay (ELISA). O diagnóstico e separação ou descarte dos animais soropositivos associado ao uso de certas práticas de manejo, especialmente das crias, são os principais meios implementados para prevenir a disseminação de SRLV, uma vez que ainda não existe vacina contra o vírus. As estratégias adotadas pelos SRLV para enfrentar o sistema imune dificultam o diagnóstico da infecção, controle ou prevenção da disseminação de SRLV. Esta revisão apresenta alguns aspectos das lentivíroses de pequenos ruminantes baseadas em estudos filogenéticos de amostras isoladas, aspectos clínicos e imunopatológicos.
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DeMartini JC, Halsey W, Boshoff C, York D, Howell MD. Comparison of a maedi-visna virus CA-TM fusion protein ELISA with other assays for detecting sheep infected with North American ovine lentivirus strains. Vet Immunol Immunopathol 1999; 71:29-40. [PMID: 10522784 DOI: 10.1016/s0165-2427(99)00083-5] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/25/2022]
Abstract
A maedi-visna virus CA-TM fusion protein ELISA (MVV ELISA) was evaluated for the detection of antibody in sheep infected with North American ovine lentivirus (OvLV). The results of the MVV ELISA were compared with other assays for OvLV antibody and with viral infection in an intensively studied group of 38 sheep with a high prevalence of OvLV infection and disease. The sensitivity, specificity, and concordance of assays for OvLV antibody (MVV ELISA, indirect ELISA, Western blot, and AGID), virus (virus isolation, PCR, antigen ELISA), and OvLV-induced disease in each animal were compared with OvLV infection status as defined by a positive result in two or more of the assays. Five sheep met the criteria for absence of OvLV infection. The sensitivity of the MVV ELISA in detecting OvLV infected sheep was 64%, whereas the sensitivity of the other three tests for antibody ranged from 85 to 94%. All the antibody assays were 100% specific in this group of animals. Of the assays for virus, the PCR test had the highest sensitivity and the best concordance with OvLV infection, but it also had the lowest specificity of any of the virus or antibody assays. Among the antibody tests, the concordance of the MVV ELISA compared most favorably with the AGID test for detecting OvLV-infected sheep. Analysis of serum samples from 28 lambs experimentally-infected with one of three North American strains of OvLV suggested that there were no significant strain differences detectable by antibody assay. Twenty virus-inoculated lambs were positive by both the MVV ELISA and the AGID test, five lambs were MVV ELISA negative and AGID test positive, and three lambs were MVV ELISA positive and AGID test negative. No pre-inoculation samples were positive by either assay. In a longitudinal study involving seven lambs, antibodies to OvLV were detected by AGID 3-5 weeks post-inoculation, but were not detected by MVV ELISA until 5-10 weeks post-inoculation. Among 128 naturally and experimentally-infected sheep that were seropositive in the AGID test, the overall sensitivity of the MVV ELISA was higher in the naturally infected sheep (84%) than in the experimentally infected sheep (69%). The data indicated that the MVV ELISA represents a less sensitive, but specific alternative for the detection of OvLV antibodies.
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Affiliation(s)
- J C DeMartini
- Department of Pathology, Colorado State University, Fort Collins 80523, USA
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14
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Affiliation(s)
- R S Campbell
- Australian Institute of Tropical Veterinary and Animal Sciences, James Cook University, Townsville, Queensland, Australia
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15
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Keen JE, Hungerford LL, Littledike ET, Wittum TE, Kwang J. Effect of ewe ovine lentivirus infection on ewe and lamb productivity. Prev Vet Med 1997; 30:155-69. [PMID: 9234419 DOI: 10.1016/s0167-5877(96)01101-4] [Citation(s) in RCA: 39] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/04/2023]
Abstract
We used a previously described sensitive and specific ovine lentivirus (OLV) recombinant transmembrane (rTM) protein enzyme-linked immunosorbent assay (ELISA) to detect anti-OLV antibodies and define OLV infection in breeding ewes from nine US Meat Animal Research Center (MARC) flocks. We estimated the production impacts of dam rTM ELISA seropositivity on ewe and lamb productivity in the birth-to-weaning interval using production data from 1466 breeding ewes (of which 1242 actually lambed) and their 2452 lambs born in spring 1992 using several multiple linear and logistic regression models. By adjusting for lamb weaning age, gender, type of birth and rearing, birth difficulty, dam age, and flock, the component of ewe or lamb productivity related to ewe OLV infection alone was isolated. The rTM ELISA-negative ewes produced significantly more total weight of weaned lamb per ewe-lambing (3.84 kg) and per ewe ram-exposed (4.95 kg) compared to their OLV-positive flockmates. Negative ewes also weaned 0.11 more lambs per ewe-lambing and 0.09 more lambs per ewe ram-exposed, gave birth to 0.13 more lambs per ewe ram-exposed, and were more likely to lamb after breeding (odds ratio (OR) = 1.9) compared to equivalent OLV-positive ewes. Lambs reared by OLV-negative ewes weighed 0.15 kg more at birth, gained 8 g more per day through weaning, and weighed 0.59 kg more at 56-day weaning. Preweaning mortality was lower (OR = 0.8) among lambs born to OLV-negative compared to OLV-positive ewes, although this difference was not significant. Our results suggest that subclinical OLV infection has important detrimental effects on sheep production which occur in cumulative fashion from breeding through weaning and that OLV control efforts may be financially justified in some sheep flocks.
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Affiliation(s)
- J E Keen
- US Meat Animal Research Center, USDA, Clay Center, NE 68933, USA
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