1. Caprine Arthritis and Encephalitis KATIE SIMPSON, DVM, MS, DACVIM CROSS TIMBERS LARGE ANIMAL CLINIC APRIL 30, 2016

2. Outline  Etiology  Transmission  Pathogenesis  Clinical Signs  Diagnosis  Prevention  Other Lentiviruses

3. Introduction  1 st recognized1974 in USA  Switzerland 1969  Worldwide  Economically important  ↑ Cull rates  5-10% arthritis  ↑ Incidence  ↓ Productivity

4. Etiology  Family Retroviridae  Oncogenic  Non-oncogenic  Genus Lentivirus  “Slow Viruses”  Chronic degenerative disease  Long incubation  Life-long persistence! Once they are infected, they are infected for life

5. Etiology…  Lentiviruses…  Caprine Arthritis-Encephalitis Virus (CAEV): Goats  Maedi-Visna Virus (MVV): Sheep  Bovine Immunodeficiency Virus (BIV)  Equine Infectious Anemia (EIA)  Feline Immunodeficiency Virus (FIV)  Human Immunodeficiency virus (HIV)

6. Etiology…  Lentiviruses…  Icosahedral, Enveloped, Single-stranded, RNA  Replication cycle  Integration of viral DNA (provirus) into host’s chromosomes

7. Etiology…  Lentiviruses…  Similar genomic organization  gag gene  Group specific antigen  Matrix, capsid, nucleic acid-binding proteins  pol gene  Polmerase  Reverse transcription, integration viral DNA into cell’s  env gene  Envelope  2 envelope glycoproteins  Transmembrane (TM) protein  Surface (SU) protein

8. Etiology…  Closely related to MVV  Genetically distinct  Morphologically/physically the same  Comparable syndromes  Cross-species transmission  Experimental

9. Etiology…  Serum antibodies = infection  Different strains  No tissue tropism

10. Transmission  Lactogenic (milk, colostrum)  Target organ  Mammary gland  Macrophages  Epithelial cells

11. Transmission…  Lactogenic…  Nursing dam  Even subclinical  Pooled colostrum  Adams et. al. 1983  Cell free and cell-associated virus  Survived concentration and freezing

12. Transmission…  Transplacental  Occurs, unknown rate  5-10%  Lamara et. al. 2001  In vitro infection of oviduct epithelial cells  No reports of in vivo occurrence

13. Transmission…  Transplacental…  Lamara et. al. 2002  8-16 cell stage embryos infected if zona pellucida removed  Zona pellucida protective mechanisms

14. Transmission…  Transplacental…  Rowe and East 1997  Animals fed pasteurized or substitute milk  10% seroconversion

15. Transmission…  Transplacental…  Adams et. al. 1983  1/10 seropositive, after 4 mo.  Another (+) after 32 mo.  Lower rate of transmission  Houwers et. al. 1983  2/389 lambs colostrum-deprived seroconverted

16. Transmission…  Transplacental…  MVV  <60 d. abortion/resorption  Later in gestation  Cutlip et. al. 1981 isolated virus 100 d. fetus  Dam seronegative, exposed to seropositive

17. Transmission…  Horizontal transmission ( one juvenile/adult to another )  Intense management  High stocking density  Also poor management, poor hygiene  Possibly through saliva, nasal secretions, urine, feces, blood  Older animals  Possible delayed latent neonatal infection

18. Transmission…  Other means  Shared milking facilities  Milking infected w/non-infected  Iatrogenic  Venereal  Not proven

19. Transmission…  Factors  Viral strain  Viral load  Route of exposure  Age  ↑ Seroprevalence w/ age

20. Transmission…  Factors…  Breed  ↓ Prevalence in Saanen, Golden Guernsey  Genetic factors  Saanens tend to have lower risk of arthritis  Stress  Immunosupression  2° infections

21. Pathogenesis  Mechanisms unclear  Subclinical infections common  Prepatent period varies  Host cell  Monocyte/macrophage (type of white blood cell)  Restricted replication  Transcription monocytes → macrophages  Undetected in monocytes

22. Pathogenesis…  Viral load ↓ in asymptomatic  Cell mediated immunity  Synovial fluid/tissues  CD8 + cytotoxic T-cells  ↑ [IgG]  ↓ level immune stimulation  Genetic predisposition  Similar to Rheumatoid Arthritis (RA)

23. Pathogenesis…  Infected macrophages in all tissues  Alter cytokine production  Stimulate immune response  Released in RA  Nitric oxide synthase  ↑ In joints  Role unknown

24. Pathogenesis…  Antibody detection  May take weeks → months  Suggested that Abs  Don’t protect…  Enhance infection  Immune complexes taken up by macrophages  Seen w/ HIV and FIV

25. Pathogenesis…  Arthritis: Similar to RA  Infiltration of synovial membranes  Disease related changes of articular (joint) surface  ↓ IL-2 expression  Cytokine pattern altered

26. Pathogenesis…  HIV  2-50% rheumatic manifestations  MHC class II+ cells  Present host cells to lymphocytes  Enhance auto-immune disease  Structural homology w/ some virus glycoproteins

27. Clinical Signs  Chronic inflammatory lesions  Most subclinical (NOT apparent)  Seroprevalence 0-81%  25-30% develop disease

28. Clinical Signs…  4 (5) clinical manifestations:  Arthritis  Encephalitis  Interstitial pneumonia  Indurative mastitis  +/- Chronic weight loss

29. Clinical Signs…  Arthritis  “Big Knee”  Adults > 1 year  Predominant form  Course varies

30. Clinical Signs…  Carpal joints > tarsal, stifle, fetlock joints, atlanto- occipital bursa > coxofemoral joint  All synovial membranes  Tendons, bursa, periarticular tissues

31. Clinical Signs…  Arthritis…  Early signs subtle  Periarticular swelling of carpus (knee)  Fluctuant, cool, not painful to palpation  Painful & debilitating  Collapse of joint, ankylosis  Severe flexion of carpus  “Knee walkers”  Hindlimb swelling less obvious  Gait may resemble incoordination

32. Clinical Signs…  Arthritis…  Most often painful & debilitating  Weight loss, reluctance to move  Firm swelling, inflammation/thickening of joint capsule & associated structures  Mineralization of joint capsule, soft tissues  Collapse of joint, ankylosis  Severe flexion of carpus  “Knee walkers”  Hindlimb swelling less obvious  Thickening of periarticular tissues  Gait may resemble incoordination

33. Clinical Signs…  Arthritis…  Synovial (joint or tendon) fluid  Acute  Serous  Dark-yellow or blood tinged  Fibrin, lymphocytes/macrophages  Chronic  Normal

34. Clinical Signs…  Viral Leukoencephalomyelitis ( brain/spine involvement)  2-6 months old  Develop slowly  Afebrile progressive paralysis  Lameness, ataxia, hindlimb CP deficits  Asymmetric  Hypertonia, hyperreflexia

35. Clinical Signs…  Viral Leukoencephalomyelitis…  Initially BAR  Continue to eat and drink  Progresses to paralysis, usually  Can also see CNS signs  Depression, blindness, abnormal PLRs, nystagmus, opisthotonos ( stargazing ), head tremor, head tilt, circling, facial nerve deficits, dysphagia, paddling  Rarely recover

36. Clinical Signs…  Interstitial pneumonia  Not reproducible  Secondary to other processes  Viral, bacterial agents  Parasitic  Chronic, non-suppurative  Progressive dyspnea (difficulty breathing)  Usually after stress  Weeks to months

37. Clinical Signs…  Interstitial pneumonia…  Exercise intolerance, wasting, cough  Arthritis  Similar to pulmonary CL

38. Clinical Signs…  Indurative mastitis  “Hard udder” or “Hard bag”  Non-suppurative  Agalactia/hypogalactia  Milk appears normal  Come into milk over weeks  Symmetrical enlargement of udder  Enlarged supramammary lymph nodes

39. Clinical Signs…  Indurative mastitis…  Smith and Cutlip 1988  Associated w/ poor production  Milk production, butter fat content, solids nonfat content, somatic cell count  Predisposed to nonhemolytic staph. mastitis

40. Clinical Signs…  Indurative mastitis…  Sanchez et. al. 2001  SCC significantly higher in CAE (+)  Nord and Adnoy, 1997  No difference in (-) and (+)  > SCC for 2 year old (+)

41. Clinical Signs…  Indurative mastitis…  Greenwood 1995  ↑ reproductive failure, ↓ kid birth weights  ↓ Growth rate, ↓ milk yields, ↓ days in milk

42. Diagnosis  Presumptive  History  Clinical signs  R/O other causes  No “Gold Standard”

43. Diagnosis  Virus isolation  Most definitive diagnosis  Viral load low  Usually negative  Indicator cell lines  Goat synovial membrane  Milk epithelial cells  Fetal membrane cells

44. Diagnosis…  Serology ( detecting antibodies )  Most convenient  Ab fluctuations  Agar Gel Immuodiffusion (AGID)  Enzyme-linked Immunosorbent Assay (ELISA)  Radioimmunoprecipitation (RIPA)  Radioimmunoassay (RIA)  Western Blot (WB)

45. Diagnosis…  AGID  Most common  Detects Abs  p28 core antigen  gp135 envelope antigen  Sensitivity 91%  Specificity 100%  No false positives

46. Diagnosis…  ELISA  Many different types  Whole virus  Recombinant  Competitive  Sensitivity and specificity vary

47. Diagnosis…  Whole virus ELISA  Whole virus antigens  Sensitivity ranged from 92-100%  Specificity ranged from 93-100%  Recombinant ELISA  Recombinant or peptide antigens  Sensitivities and specificities vary

48. Diagnosis…  Competitive ELISA  Most common ELISA used  Sensitivity 93-100%  Specificity 96.4-100%

49. Diagnosis…  ELISA vs. AGID  ELISA > proportion of Abs detected  ELISA detects seroconversion earlier  AGID ↓ Sensitivity  AGID less $$$

50. Diagnosis…  RIPA, RIA, WB  Not screening tests  Time consuming  May lead to false conclusions  Sensitivity, Specificity not established  WB  Most commonly used  More sensitive than AGID

51. Diagnosis…  PCR ( finding viral DNA )  Less sensitive than ELISA  Detect infection before seroconversion  Not fully developed  Combination w/ELISA  Optimal detection

52. Prevention  Based on  Minimize doe → kid transmission  ID infected animals  Minimize contact between (-) and (+)  Eliminate infected animals

53. Prevention…  Adams et. al. 1983  5 steps to prevent transmission to kids  Immediate removal from dam  +/- wash kids  Isolate kids  2 meters btw kids & infected animals

54. Prevention  Steps to prevent transmission  Use CAEV-free or heat treated colostrum  56˚ C for 1 hour  Use CAEV-free milk, pasteurized milk  Test at 6 month intervals  Separate (+) and (-)

55. Prevention…  Test and Cull  Not an option if  No virus free replacements  High seroprevalence  Not economically feasible  Lose genetic potential

56. Prevention…  Test and Segregate  Keep 2 herds  Regular testing  To be effective must  Eliminate shared feeders/waters  Walls, double fences  Record escapees/exposures  Avoid commingling

57. Prevention…  Current recommendations  Multifaceted  Realize seronegative ≠ negative infection  Prevent perinatal/lactogenic transmission  Serologic surveillance  Segregate/cull (+)  Milk seronegative 1st  Avoid  Iatrogenic transmission  Potential venereal

58. Prevention…  Vaccination  Not effective  McGuire et. al. 1986  Vaccinated w/inactivated CAEV  Increased severity, onset of arthritis  Immune response plays a role in CAE arthritis

59. Other Lentiviruses  EIA  Equidae only  Source of infection = infected animals  Persistent infection  Clinically normal  Clinically infected

60. Other Lentiviruses…  EIA…  Transmission  Contaminated blood  Mechanical Vectors  Biting insects  Intrauterine  Iatrogenic  Semen

61. Other Lentiviruses…  EIA…  Replicates in macrophages  Incubation 2-4 weeks  Clinical signs  Weight loss, ataxia, fever  Jaundice, ventral edema, petechiation  Abort  Temporary relapses

62. Other Lentiviruses…  EIA…  Clin Path  Thrombocytopenia, anemia  Sideroleukocytes  Hypergammaglobulinemia  ↑ Bilirubin  ↓Serum iron

63. Other Lentiviruses…  EIA…  Diagnosis  Detection of Abs to p26 core Ag  AGID aka Coggins  cELISA  Detects lower [Ab]  Verify w/AGID

64. Other Lentiviruses  EIA…  False (-)s  Lack of p26 Ag  Recent infections  False (+)s  Foals born to infected mares  Up to 6 months after birth

65. Other Lentiviruses…  FIV  1 st reported 1986  Pyrexia, gingivitis, diarrhea, weight loss  Morphologically similar to HIV  Antigenically different  Model for HIV??

66. Other Lentiviruses…  FIV…  Transmission  1˚ bite wounds  Older, outdoor, male cats  Queen → kittens  Artificial insemination

67. Other Lentiviruses  FIV…  Replicates in  T-lymphocytes (CD4+ & CD8+)  B-lymphocytes  Macrophages  Astrocytes

68. Other Lentiviruses…  FIV…  Initially  Fever, neutropenia, generalized lymphadenopathy  Subclinical latent period

69. Other Lentiviruses…  FIV…  Age of infection ~ 3 years  Clinical illness ~ 10 years  Slow ↓  CD4+ lymphocytes  Cytokines (IL-2 & IL-10)  Different clinical syndromes  2° infections

70. Other Lentiviruses  FIV…  Diagnosis  CBC suggestive  BM aspirate  ELISA  Virus isolation or PCR or Western Blot  Vaccination = positive tests

71. Conclusions

72. Thanks

73. QUESTIONS?