Neosporosis in Animals

549 Pages·2017·125.807 MB·English

by  J.P. Dubey, A. Hemphill, R. Calero-Bernal, Gereon Schares

Neosporosis in Animals

Neosporosis in Animals
J. P. Dubey
Animal Parasitic Diseases Laboratory
Beltsville Agricultural Research Center
Agricultural Research Service
U.S. Department of Agriculture
Beltsville, Maryland 20705
A. Hemphill
Institute of Parasitology,
Department of Infectious Diseases and Pathobiology
Vetsuisse Faculty
University of Bern
Länggass-Strasse 122
CH-3012 Bern, Switzerland
R. Calero-Bernal
Animal Parasitic Diseases Laboratory
Beltsville Agricultural Research Center
Agricultural Research Service
U.S. Department of Agriculture
Beltsville, Maryland 20705
G. Schares
Institute of Epidemiology
Friedrich-Loeffler-Institut
Bundesforschungsinstitut für Tiergesundheit
Federal Research Institute for Animal Health
Südufer 10,
17493 Greifswald—Insel Riems, Germany
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Library of Congress Cataloging‑in‑Publication Data
Names: Dubey, J. P., author. | Hemphill, A., author. | Schares, G., author. |
Calero-Bernal, R. (Rafael), 1983- author.
Title: Neosporosis in animals / J.P. Dubey, A. Hemphill, G. Schares, and R.
Calero-Bernal.
Description: Boca Raton : Taylor & Francis, 2017. | Includes bibliographical
references.
Identifiers: LCCN 2016042634| ISBN 9781498752541 (hardback : alk. paper) |
ISBN 9781498752565 (ebook)
Subjects: LCSH: Veterinary parasitology. | MESH: Parasitic Diseases, Animal
Classification: LCC SF810.A3 D79 2017 | NLM SF 810.A3 | DDC 636.089/696--dc23
LC record available at https://lccn.loc.gov/2016042634
Visit the Taylor & Francis Web site at
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and the CRC Press Web site at
http://www.crcpress.com
Contents
Preface............................................................................................................................................xiii
Authors .............................................................................................................................................xv
Abbreviations Commonly Used .....................................................................................................xvii
Chapter 1
History of Neospora and Neosporosis ...............................................................................................1
1.1 History .....................................................................................................................................1
1.1.1 Discovery of the Organism in Dogs ..........................................................................1
1.1.2 In Vitro Cultivation of Viable N. caninum .................................................................2
1.1.3 Linking N. caninum to Abortions in Cattle ...............................................................2
1.1.4 Retrospective Studies .................................................................................................3
1.1.4.1 Dogs in USA ...............................................................................................3
1.1.4.2 Dogs in Norway ..........................................................................................3
1.1.5 Cattle and Other Hosts ...............................................................................................5
1.2 Landmarks in the Biology of Neospora ..................................................................................5
Bibliography ......................................................................................................................................5
Chapter 2
General Biology .................................................................................................................................7
2.1 Introduction .............................................................................................................................7
2.2 Taxonomic Classification ........................................................................................................7
2.3 Hosts ........................................................................................................................................8
2.3.1 Definitive Hosts..........................................................................................................8
2.3.2 Intermediate Hosts .....................................................................................................8
2.4 Life Cycle Stages .....................................................................................................................8
2.4.1 Tachyzoite ..................................................................................................................9
2.4.2 Bradyzoites and Tissue Cysts ..................................................................................20
2.4.2.1 Conversion of Tachyzoites to Bradyzoites................................................23
2.4.3 Oocyst ......................................................................................................................26
2.5 Transmission and Epidemiology ...........................................................................................30
2.6 Host–Parasite Relationship ...................................................................................................32
2.7 Molecular and Cell Biology ..................................................................................................35
2.7.1 Genome and Transcriptome Analysis of N. caninum ..............................................35
2.7.2 Modulation of Host Gene Expression upon Infection .............................................40
2.7.3 Proteomics Approaches ...........................................................................................41
2.7.4 Genetic Manipulation of N. caninum ......................................................................41
2.7.5 Neospora–Host Cell Interactions and Invasion .......................................................42
2.7.5.1 Initial Host Cell Contact is Mediated by Parasite Surface
Antigens (SAGs) .......................................................................................43
2.7.5.2 Secretory Organelle Discharge Governs Host Cell Invasion ...................50
2.7.5.3 Microneme Proteins .................................................................................50
2.7.5.4 ROPs and Rhoptry Neck Proteins (RONs) ...............................................50
2.7.5.5 Dense Granule Proteins ............................................................................51
2.7.5.6 Intracellular Host Cell Modulation and Parasite–Host Cell Crosstalk ....52
2.7.5.7 Monoclonal Antibodies ............................................................................53
2.8 Rodent Models of Neosporosis .............................................................................................53
v
vi Contents
2.8.1 Mice .........................................................................................................................53
2.8.1.1 Outbred Mice ...........................................................................................53
2.8.1.2 Inbred Mice ..............................................................................................57
2.8.1.3 Nude Mice and IFN-γ-KO Mice ..............................................................70
2.8.2 Gerbils ......................................................................................................................70
2.8.2.1 Common Pet Gerbil (Meriones unguiculatus) .........................................70
2.8.2.2 Tristram’s Jird (Meriones tristrami) .........................................................73
2.8.2.3 Wagner Gerbil (Gerbillus dasyurus) ........................................................73
2.8.3 Multimammate Rat (Mastomys natalensis) .............................................................73
2.8.4 Sand Rat (Psammomys obesus) ...............................................................................73
2.8.5 Norwegian Rat (Rattus norvegicus) .........................................................................73
2.8.6 Djungarian Hamster (Phodopus sungorus) .............................................................74
2.9 General Diagnosis .................................................................................................................74
2.9.1 Cytology ...................................................................................................................74
2.9.2 Conventional Histopathology ...................................................................................74
2.9.3 Transmission Electron Microscopy .........................................................................74
2.9.4 Immunohistochemical Staining (IHC) ....................................................................75
2.9.5 Isolation of Viable N. caninum by Bioassay ............................................................76
2.9.6 Serological Methods ................................................................................................77
2.9.6.1 Antibody Detection ..................................................................................77
2.9.6.2 Antigen Detection ....................................................................................90
2.9.7 Detection of DNA (PCR) .........................................................................................90
2.9.7.1 General Aspects of PCR ..........................................................................90
2.9.7.2 Target Genes for Diagnostic N. caninum PCRs .......................................91
2.9.7.3 Quantitative PCR .....................................................................................97
2.9.7.4 Typing Different Neospora sp. Strains .....................................................98
2.10 Treatment ............................................................................................................................101
2.11 Vaccines ..............................................................................................................................104
2.11.1 Vaccination Studies in Small Laboratory Animals ...............................................104
2.11.1.1 Live Vaccines .........................................................................................104
2.11.1.2 Subunit Vaccines ....................................................................................111
2.12 Prevention, Prophylaxis ......................................................................................................111
Bibliography ..................................................................................................................................111
Chapter 3
Techniques .....................................................................................................................................115
3.1 Bioassay of Tissues for Isolation of Neospora ....................................................................115
3.1.1 Tissues of Acutely Infected Animals .....................................................................115
3.1.2 Tissues of Chronically Infected Animals ..............................................................115
3.2 Parasite Cultures .................................................................................................................116
3.2.1 Obtaining Tachyzoites ...........................................................................................116
3.2.1.1 In Vitro Cultivation ................................................................................116
3.2.2 Obtaining Tissue Cysts ..........................................................................................119
3.2.3 Obtaining Oocysts .................................................................................................119
3.2.4 Cryopreservation ....................................................................................................120
3.3 Diagnostic Procedures ........................................................................................................120
3.3.1 Examination of Canine Feces for Oocysts ............................................................120
3.3.2 Cytology, Histopathologic, and IHC Procedures ...................................................121
3.3.3 Serologic Procedures .............................................................................................124
Contents vii
3.3.3.1 NAT ........................................................................................................124
3.3.3.2 IFAT .......................................................................................................124
3.3.3.3 ELISAs ...................................................................................................125
3.3.3.4 Immunoblots...........................................................................................127
3.3.4 PCR ........................................................................................................................130
3.3.4.1 Sampling, Sample-Treatment and DNA Extraction ...............................130
3.3.4.2 Fecal, Environmental, and Water Samples ............................................131
3.3.4.3 Options for Transporting DNA Prior to Analysis ..................................132
Bibliography ..................................................................................................................................132
Chapter 4
Neosporosis in Cattle .....................................................................................................................133
4.1 Natural Infections ...............................................................................................................133
4.1.1 Serologic Prevalence ..............................................................................................133
4.1.2 Clinical Infections..................................................................................................133
4.1.2.1 Abortion and Stillbirth ...........................................................................133
4.1.2.2 Congenitally Infected Calves .................................................................175
4.1.2.3 Lesions in Weaned Calves and Adult Cattle ..........................................178
4.1.3 Isolation of Viable N. caninum from Bovine Tissues ............................................180
4.2 Experimental Infections ......................................................................................................183
4.2.1 Calves and Adult Cattle .........................................................................................183
4.2.2 Cows during Pregnancy .........................................................................................191
4.2.2.1 Early Studies ..........................................................................................191
4.2.2.2 Pathogenesis of Neosporosis ..................................................................191
4.3 Diagnosis .............................................................................................................................203
4.3.1 General Considerations ..........................................................................................203
4.3.2 Submission of Samples to a Diagnostic Laboratory ..............................................204
4.3.3 Routine Histopathological Examination ................................................................204
4.3.4 Immunohistological Examinations ........................................................................205
4.3.5 Demonstration of Viable Neospora .......................................................................207
4.3.6 Detection of N. caninum DNA ..............................................................................207
4.3.6.1 Clinical Cases .........................................................................................208
4.3.6.2 Asymptomatic Cattle ..............................................................................209
4.3.7 Detection of Antibodies .........................................................................................209
4.3.7.1 Antibody Types and Isotypes .................................................................209
4.3.7.2 Ratio of Specific IgG1 and IgG2 ............................................................210
4.3.7.3 Fluctuating Antibody Levels in Relation to Risk of
Abortion and Vertical Transmission ......................................................210
4.3.7.4 Avidity Maturation .................................................................................211
4.3.7.5 Antibodies in Adult Cattle due to Vaccination ......................................211
4.3.7.6 Antibodies in Fetuses .............................................................................211
4.3.7.7 Antibodies in Newborn Calves ..............................................................212
4.3.7.8 In-House and Commercial Serological Assays ......................................213
4.3.7.9 Testing of Individual Aborting Dams or Dams at Abortion Risk ..........222
4.3.7.10 Serological Testing on a Herd Level ......................................................223
4.3.7.11 Avidity Tests to Define the Time Point of Infection ..............................224
4.3.7.12 Serological Tests to Estimate the Herd Seroprevalence .........................224
4.4 Epidemiology ......................................................................................................................225
4.4.1 Transmission and Risk Factors in Cattle ...............................................................225
viii Contents
4.4.1.1 Prenatal (Transplacental) Transmission .................................................225
4.4.1.2 Postnatal (Horizontal) Transmission ......................................................228
4.4.1.3 Epidemic and Endemic N. caninum-Associated Abortion ....................229
4.4.1.4 Persistent N. caninum Infection and Fertility ........................................230
4.4.1.5 Effect of Infection on Fetal Survival ......................................................230
4.4.2 Risk Factors Associated with Infection .................................................................230
4.4.2.1 Age .........................................................................................................231
4.4.2.2 Parity Number of Dam ...........................................................................236
4.4.2.3 Definitive Hosts (e.g., Dogs, Coyotes, and Wolves) ...............................236
4.4.2.4 Carnivores Other than Canids ................................................................237
4.4.2.5 Intermediate Hosts Other than Cattle ....................................................237
4.4.2.6 Grazing, Fodder, and Drinking Water ...................................................238
4.4.2.7 Feeding Colostrum or Milk ....................................................................239
4.4.2.8 Calving Management .............................................................................239
4.4.2.9 History of Reproduction Problems .........................................................239
4.4.2.10 Cattle Stocking Density and Size of Farm Land ....................................239
4.4.2.11 Herd Size ................................................................................................240
4.4.2.12 Source of Replacement Heifers ..............................................................240
4.4.2.13 Breed ......................................................................................................240
4.4.2.14 Type of Cattle .........................................................................................241
4.4.2.15 Type of Housing .....................................................................................241
4.4.2.16 Hygienic Status and Biosecurity ............................................................241
4.4.2.17 Factors Related to Concurrent Infections ...............................................241
4.4.2.18 Climatic Season ......................................................................................242
4.4.2.19 Vegetation ...............................................................................................242
4.4.2.20 Human Population Density ....................................................................242
4.4.2.21 Geographic Clustering ...........................................................................242
4.4.3 Risk Factors Associated with Reproduction ..........................................................243
4.4.3.1 Abortion Risk Associated with Seropositivity of Individual Cattle .......243
4.4.3.2 Abortion Risk Associated with N. caninum Seroprevalence
in the Herd ..............................................................................................244
4.4.3.3 Factors Related to Infection Risk ...........................................................244
4.4.3.4 Factors Associated with Reproduction ...................................................251
4.5 Economics and Control of Bovine Neosporosis .................................................................253
4.5.1 Economic Considerations ......................................................................................253
4.5.2 Vaccination against Neosporosis in Cattle ............................................................254
4.5.2.1 Live-Attenuated Vaccines ......................................................................254
4.5.2.2 N. caninum Tachyzoite Lysate-Based Vaccines .....................................256
4.5.2.3 Subunit Vaccines ....................................................................................257
4.5.3 Reproductive Management ....................................................................................258
Bibliography ..................................................................................................................................259
Chapter 5
Neosporosis in Dogs ......................................................................................................................261
5.1 Natural Infections ...............................................................................................................261
5.1.1 Sources of Infection and Transmission of N. caninum for Dogs ...........................261
5.1.2 Serologic Prevalence ..............................................................................................261
5.1.2.1 Risk Factors for Infection in Dogs .........................................................262
Contents ix
5.1.3 Prevalence of N. caninum Oocysts in Dog Feces ..................................................275
5.1.4 Isolation of Viable N. caninum from Dogs ............................................................275
5.1.5 Clinical Infections..................................................................................................275
5.2 Diagnosis of Canine Neosporosis and Canine N. caninum Infection.................................295
5.2.1 General Considerations on Clinical Examination .................................................295
5.2.2 Histopathologic Diagnosis .....................................................................................295
5.2.2.1 Antemortem Findings ............................................................................296
5.2.2.2 Lesions in Dogs with Canine Neosporosis, Postmortem Findings ........298
5.2.3 Demonstration of Viable N. caninum in Dogs .......................................................300
5.2.3.1 Demonstration of Viable N. caninum in Cases of
Canine Neosporosis .............................................................................300
5.2.3.2 Demonstration of Viable N. caninum Oocysts .......................................302
5.2.4 Detection of N. caninum DNA in Dogs .................................................................302
5.2.4.1 N. caninum DNA in Canine Neosporosis ..............................................302
5.2.4.2 N. caninum DNA in Canine Feces .........................................................303
5.2.4.3 Genotyping of N. caninum Strains Isolated from Dogs .........................303
5.2.5 N. caninum-Specific Antibodies in Dogs with Canine Neosporosis .....................303
5.2.5.1 Antibody Development and Antibody Types .........................................305
5.2.5.2 Persistence of Antibodies .......................................................................305
5.2.5.3 Antibodies and Vertical Transmission in Dogs ......................................305
5.2.5.4 Antibodies in Dogs with Myositis, Polyradiculoneuritis, and
Encephalomyelitis ..................................................................................306
5.2.5.5 Antibodies in Dogs with Other Forms of Canine Neosporosis .............308
5.2.5.6 Antibody Detection in CSF ....................................................................308
5.2.5.7 Effect of chemotherapeutical Treatment on Antibody Levels ...............308
5.2.5.8 Avidity Maturation of a Specific IgG Response in Dogs .......................308
5.2.6 Serological Reactions in Dogs after Excreting Oocysts ........................................308
5.2.6.1 Reactions against Conventional Tachyzoite Antigen .............................308
5.2.6.2 Serological Reactions against a 152 kDa Tachyzoite Antigen in
Oocyst Shedding Dogs ...........................................................................309
5.2.7 Serological Assays .................................................................................................309
5.2.7.1 Available Types of Assays ......................................................................309
5.2.7.2 Commercial Assays ................................................................................310
5.3 Therapy ...............................................................................................................................310
5.4 Prevention ............................................................................................................................310
5.5 Experimental Infections ......................................................................................................314
5.5.1 Using Dogs as Intermediate Hosts .........................................................................314
5.5.2 Using Dogs as Definitive Hosts .............................................................................315
Bibliography ..................................................................................................................................315
Chapter 6
Neosporosis in Sheep .....................................................................................................................317
6.1 Natural Infections ...............................................................................................................317
6.1.1 Serologic and DNA Prevalence .............................................................................317
6.1.2 Clinical Infections..................................................................................................317
6.1.2.1 Histologically Confirmed Abortion and Stillbirth .................................317
6.1.2.2 Detection of N. caninum DNA in Aborted Fetuses ...............................323
6.1.2.3 Clinical and Subclinical Neosporosis in Adult Sheep ...........................323