Tissue sets from 36 snatch-farrowed colostrum-deprived (SF/CD) and 71 Caesarian-derived gnotobiotic swine infected with porcine circovirus type 2 (PCV-2) as neonates were examined and scored for the types and tissue distribution of histologic lesions associated with this viral infection. The occurrence and severity of these lesions were correlated with qualitative and quantitative determinations of viral burden in tissues by immunohistochemistry (IHC) and tissue titrations for infectious virus, respectively. These measures were, in turn, related to 1 of 3 categories of clinical disease expressed in PCV-2–infected swine as subclinical infection, preclinical postweaning multisystemic wasting syndrome (PMWS), and clinically evident PMWS, respectively. Statistically significant (P < 0.05 to 0.001) associations between both measures of viral burden, the severity of histologic lesions and the stage of disease were obtained. Discrimination between and among categories of disease was best accomplished by a combination of IHC and histopathology. The results of this study confirm that viral burden in PCV-2–infected tissues, specifically lymphoid tissues and liver, directly correlate with severity of clinical disease expression in PCV-2 infected swine.
AllanGMEllisJA: 2000, Porcine circoviruses: a review. J Vet Diagn Invest12:3–14.
2.
AllanGMKennedySMcNeillyF: 1999, Experimental reproduction of wasting disease and death by co-infection of piglets with porcine circovirus and porcine parvovirus. J Comp Pathol121:1–11.
3.
AllanGMMcNeillyFEllisJA: 2000, Experimental infection of colostrum deprived piglets with porcine circovirus type 2 (PCV-2) and porcine respiratory and reproductive syndrome virus (PRRSV) potentiates PCV-2 replication. Arch Virol145:2421–2429.
4.
AllanGMMcNeillyFEllisJA: 2001, Neonatal vaccination for Mycoplasma hyopneumonia and PMWS; a field trial. Pig J48:1–15.
5.
AllanGMMcNeillyFKennedyS: 2000, Immunostimulation, PCV-2 and PMWS. Vet Rec147:170–171.
6.
BogdanJO'ConnorBAhrudM: 2001, Association of porcine circovirus 2 with reproductive failure in pigs: a retrospective study. 1995–1999. Can Vet J42:548–550.
7.
BolinSRStoffregenWCNayarGP: 2001, Postweaning multisystemic wasting syndrome induced after experimental inoculation of Caesarian-derived, colostrum deprived piglets with type 2 circovirus. J Vet Diagn Invest13:185–194.
DroletRThibaultSD'AllaireS: 1999, Porcine dermatitis and nephropathy syndrome (PDNS): an overview of the disease. Swine Health Prod7:283–285.
10.
DulacGCAfsharA: 1989, Porcine circovirus antigens in PK-15 cell line (ATCC-CCL-33) and evidence of antibodies to circovirus in Canadian piglets. Can J Vet Res53:431–433.
11.
EllisJABratanichAClarkEG: 2000, Co-infection by porcine circoviruses and porcine parvovirus in pigs with naturally occurring post-weaning multisystemic wasting syndrome. J Vet Diagn Invest12:21–22.
12.
EllisJALairmoreMKrakowkaS: 1999, Reproduction of lesions of post-weaning multisystemic wasting syndrome in gnotobiotic piglets. J Vet Diagn Invest11:3–14.
13.
FenauxMHalburPHaqshenasG: 2002, Cloned genomic DNA of type 2 porcine circovirus is infectious when injected directly into the liver and lymph nodes of pigs: characterization of clinical disease, virus distribution, and pathologic lesions. J Virol76:541–551.
14.
GreshamAAllanGMcNeillyFKennedyS: 2001, Links between post-weaning multiystemic wasting syndrome and porcine dermatitis nephropathy syndrome. Pig J47:155–159.
15.
HamelALLinLLSachvieC: 2000, PCR detection and characterization of type-2 porcine circovirus. Can J Vet Res64:44–52.
16.
HardingJ: 1997, Post-weaning multisystemic wasting syndrome (PMWS): preliminary epidemiology and clinical presentation. Proc Am Assoc Swine Pract28:503.
17.
HarmsPASordenSHalburP: 2001, Experimental reproduction of severe disease in CD/CD pigs concurrently infected with type 2 porcine circovirus and porcine respiratory and reproductive syndrome virus. Vet Pathol38:528–539.
18.
KrakowkaSEatonKA: 1996, Helicobacter pylori infection in gnotobiotic piglets: a model of human gastric bacterial disease. In: Advances in swine in biomedical research, ed. TumblesonMSchookL, vol II, pp. 779–810. Plenum Press, New York, NY.
19.
KrakowkaSEllisJMcNeillyF: 2004, Features of cell degeneration and death in hepatic failure and systemic lymphoid depletion characteristic of PCV-2-associated postweaning multisystemic wasting disease (PMWS). Vet Pathol41:471–481.
20.
KrakowkaSEllisJAMcNeillyF: 2002, Immunologic features of porcine circovirus type 2 infection. Virol Immunol15:567–582.
21.
KrakowkaSEllisJAMeehanB: 2000, Viral wasting syndrome of swine: experimental reproduction of the disease by co-infection with porcine circovirus-2 (PCV-2) and porcine parvovirus (PPV). Vet Pathol37:254–263.
22.
KrakowkaSEllisJAMeehanB: 2001, In vivo immune activation is the pivotal event in the production of wasting disease in pig infected with porcine circovirus-2 (PCV-2). Vet Pathol38:31–42.
23.
KrakowkaSRingsDMEllisJA: 2003, The pathogenesis of porcine circovirus type 2 infection and postweaning multi-systemic wasting syndrome (PMWS). White Book Four, Merial SAS, Lyon, France.
24.
KyriakisSCSaoulidisKLekkasS: 2001, The effects of immunomodulation on the clinical and pathological expression of postweaning multisystemic wasting syndrome. J Comp Pathol126:38–46.
25.
LarochelleRBielanskiAMullerP: 2000, PCR detection and evidence of shedding of porcine circovirus type 2 in boar semen. J Clin Microbiol38:4629–4632.
26.
LarochelleRMagarRD'AllaireS: 2003, Comparative serologic and virologic study of commercial herds with and without postweaning multisystemic wasting syndrome. Can J Vet Res67:114–120.
27.
LukertPdeBoerGFDaleJL: 1995, The Circoviridae in virus taxonomy. In: The sixth report of the international committee on taxonomy of viruses, ed. MurphyFAFauquetCMBishopDHL, pp. 166–168. Springer, New York, NY.
28.
McNeillyFKennedySMoffettD: 1999, A comparison of in situ hybridization and immunohistochemistry for the detection of a new porcine circovirus in formalin-fixed tissues from pigs with postweaning multisystemic wasting syndrome (PMWS). J Virol Methods80:123–128.
29.
McNeillyFMcNairFMackieDP: 2001, Production characterization and applications of monoclonal antibodies to porcine circovirus type 2. Arch Virol146:909–922.
30.
McNeillyFMcNairIO'ConnorM: 2002, Evaluation of an antigen-capture ELISA for PCV-2 and diagnosis of PMWS in pigs. J Vet Diagn Invest14:106–112.
31.
MeehanBMMcNeillyFMcNairI: 2001, Isolation and characterization of porcine circovirus 2 from cases of sow abortion and porcine dermatitis and nephropathy syndrome. Arch Virol146:1–8.
32.
MeehanBMMcNeillyFToddF: 1998, Characterization of novel circovirus DNA's associated with wasting syndromes in pigs. J Gen Virol79:2171–2179.
33.
MikkelsenA-SNielsenJStadejekT: 2002, Reproduction of postweaning multisystemic wasting syndrome (PMWS) in immunostimulated and nonimmunostimulated conventional 3-week-old piglets experimentally infected with porcine circovirus type 2 (PCV2). Vet Microbiol22:89–97.
34.
OpriessnigTYuSGallupJM: 2003, Effect of vaccination with selective bacterins on conventional pigs infected with type 2 porcine circovirus. Vet Pathol40:521–529.
35.
Rodrigurz-ArriojaGMSegalesJCalsamigliaM: 2002, Dynamics of porcine circovirus type 2 infection in a herd of pigs with postweaning multisystemic wasting syndrome. Am J Vet Res63:354–357.
36.
RosellCSegalesJDomingoM: 2000, Hepatitis and staging of hepatic damage in pigs naturally infected with porcine circovirus type 2. Vet Pathol37:687–692.
37.
RosellCSegalesJPlana-DuranJ: 1999, Pathological, immunohistochemical and in situ hybridization studies of natural cases of postweaning multisystemic wasting syndrome (PMWS) in swine. J Comp Pathol120:59–78.
38.
SanchezRENauwynckHJMcNeillyF: 2003, Porcine circovirus-2 infection in swine fetuses inoculated at different stages of gestation. Vet Microbiol83:169–176.
39.
SarliGMandrioliLLaurentiM: 2000, Immunohistochemical characterization of the lymph node reaction in pig postweaning multisystemic wasting syndrome. Vet Immunol Immunopathol83:53–67.
40.
SegalesJDomingoM: 2002, Postweaning multisystemic wasting syndrome (PMWS) in pigs. A review. Vet Q24:109–124.
41.
ShibaharaTSatoKIshikawaY: 2000, Porcine circovirus induces B lymphocyte depletion in pigs with wasting disease. J Vet Med Sci62:1125–1131.
42.
SibilaMCalsamigliaMSegalesJ: 2004, Use of a polymerase chain reaction assay and an ELISA to monitor porcine circovirus type 2 infection in pigs from farms with and without postweaning multisystemic wasting syndrome. Am J Vet Res65:88–92.
43.
ThomsonJHendersonLMeikleC: 2001, Porcine dermatitis and nephropathy syndrome. Vet Rec148:282–283.
44.
ToddDNiagroFDRitchieBW: 1991, Comparison of three animal viruses with circular single-stranded DNA genomes. Arch Virol117:129–135.
45.
WalkerIWKonobyCAJewhurstVA: 2000, Development and application of a competitive ELISA for the detection of serum antibodies to porcine circovirus type 2. J Vet Diagn Invest12:400–405.
46.
WestKWBystromJWojnarowiczC: 1999, Myocarditis and abortion associated with intrauterine infection of sows with porcine circovirus. J Vet Diagn Invest11:530–532.
