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1.
Vet Microbiol ; 145(3-4): 209-19, 2010 Oct 26.
Artículo en Inglés | MEDLINE | ID: mdl-20409649

RESUMEN

Our primary objectives were to determine: the relative virulence of porcine circovirus (PCV) 2a and PCV2b, if heterologous infection induces severe illness, and the relative concentration of PCV2a and PCV2b in tissues of heterologously infected pigs. In experiment 1, 18 germ-free piglets served as controls or were infected with PCV2a or PCV2b. Half were immune stimulated with keyhole limpet hemocyanin (KLH) emulsified in incomplete Freund's adjuvant (2aKLH, 2bKLH). No piglets demonstrated severe illness. Lesion severity did not differ, but PCV2 capsid staining was more intense in 2a- than 2b-infected pigs (P<.05). In experiment 2, 20 germ-free piglets were dual inoculated 7 days apart with PCV2a and PCV2b (2a2b, 2b2a), PCV2b twice (2b2b), or PCV2a (2a2a) twice. Five of 9 heterologous-infected pigs developed severe illness. All heterologously infected pigs demonstrated ascites or edema, and 8/9 developed thymic atrophy. By contrast, 1 of 5 2b2b-infected pigs developed bronchopneumonia and pleural effusion. No 2a2a-infected pig developed illness. Gross lesions were more severe in heterologously infected pigs than in 2b2b pigs (P<.05), and were more severe in 2b2b than 2a2a pigs (P<.05). PCV2 capsid staining intensity did not differ by group. In heterologously infected pigs, higher levels of PCV2 DNA reflective of the first inoculum compared to the second were found in mesenteric lymph node (P=.04), spleen (P=.004) and liver (P=.04). These results indicate that dual heterologous PCV2a/2b inoculation 7 days apart may induce severe clinical illness, but PCV2a and PCV2b when administered singularly or in combination with KLH appear to be of equivalent virulence.


Asunto(s)
Infecciones por Circoviridae/veterinaria , Circovirus/patogenicidad , Síndrome Multisistémico de Emaciación Posdestete Porcino/virología , Animales , Animales Recién Nacidos , Canadá , Infecciones por Circoviridae/genética , Infecciones por Circoviridae/inmunología , Infecciones por Circoviridae/virología , Circovirus/genética , Circovirus/inmunología , ADN Viral/química , ADN Viral/genética , Genotipo , Vida Libre de Gérmenes , Inmunohistoquímica/veterinaria , Riñón/virología , Hígado/virología , Tejido Linfoide/virología , Reacción en Cadena de la Polimerasa/veterinaria , Síndrome Multisistémico de Emaciación Posdestete Porcino/genética , Síndrome Multisistémico de Emaciación Posdestete Porcino/inmunología , Estadísticas no Paramétricas , Porcinos , Virulencia
3.
Zoonoses Public Health ; 54(5): 214-22, 2007.
Artículo en Inglés | MEDLINE | ID: mdl-17542965

RESUMEN

Porcine circovirus type 2 (PCV2) infection is now recognized as the major factor in the development of post-weaning multisystemic wasting syndrome (PMWS). Although Koch's postulates have been fulfilled for PCV2 and PMWS, the severe clinical expression of the disease observed in field cases has been difficult to reproduce experimentally. Some studies have demonstrated that immune stimulation associated with the use of some commercially available swine vaccines may trigger progression of PCV2 infection to disease and lesions characteristic of PMWS. Here we describe the effects on PCV2 infection in an experimental model following the use of a commercially available modified live vaccine to porcine respiratory and reproductive syndrome virus (PRRSV). Although none of the piglets infected with PCV2 developed clinical PMWS, the severity of microscopical lesions and the PCV2 antigen load associated with these lesions were higher in the PRRSV-vaccinated piglets compared with those detected in the PCV2 only infected animals.


Asunto(s)
Infecciones por Circoviridae/veterinaria , Circovirus/fisiología , Virus del Síndrome Respiratorio y Reproductivo Porcino/inmunología , Enfermedades de los Porcinos/inmunología , Vacunas Virales/farmacología , Síndrome Debilitante/veterinaria , Animales , Animales Lactantes , Anticuerpos Antivirales/sangre , Anticuerpos Antivirales/efectos de los fármacos , Infecciones por Circoviridae/inmunología , Calostro/fisiología , Organismos Libres de Patógenos Específicos , Porcinos , Enfermedades de los Porcinos/sangre , Replicación Viral , Síndrome Debilitante/inmunología
4.
Vet Pathol ; 43(6): 956-62, 2006 Nov.
Artículo en Inglés | MEDLINE | ID: mdl-17099152

RESUMEN

Groups of gnotobiotic piglets were orally inoculated at 3 days of age with either Helicobacter heilmannii (Hh) or a newly described porcine-origin gastric Helicobacter pylori (Hp)-like bacterium. Three Hh-infected and 6 porcine Hp-like-infected swine were fed a milk replacement diet containing 5-10% (v/v) sterile corn syrup as a dietary source of fermentable carbohydrate. None of the piglets infected with Hh and supplemented with corn syrup developed gastric mucosal ulcers; 2 developed small erosive lesions in the pars esophagea. In contrast, all 6 dietary carbohydrate-supplemented Hp-like-infected swine developed severe gastroesophageal ulcers; 1 of these ex-sanguinated into the stomach and died before the end of the experiment. Four of these 6 piglets had grossly evident partially digested blood in the intestinal lumens, indicative of bleeding into the gastrointestinal tract from the stomach. These data suggest that a high carbohydrate diet and gastric colonization by porcine Hp-like bacteria facilitate development of clinically significant gastroesophageal ulcers.


Asunto(s)
Unión Esofagogástrica/microbiología , Infecciones por Helicobacter/veterinaria , Helicobacter pylori/clasificación , Enfermedades de los Porcinos/microbiología , Úlcera/veterinaria , Animales , Enfermedades del Esófago/microbiología , Enfermedades del Esófago/patología , Enfermedades del Esófago/veterinaria , Unión Esofagogástrica/patología , Mucosa Gástrica/microbiología , Mucosa Gástrica/patología , Vida Libre de Gérmenes , Infecciones por Helicobacter/microbiología , Infecciones por Helicobacter/patología , Porcinos , Enfermedades de los Porcinos/patología , Úlcera/microbiología , Úlcera/patología
5.
Res Vet Sci ; 81(2): 287-92, 2006 Oct.
Artículo en Inglés | MEDLINE | ID: mdl-16481016

RESUMEN

PCV2 infection is now recognized as the major factor in the development of post-weaning multisystemic wasting syndrome (PMWS). In this study we evaluated the use of PCR to detect the presence of PCV2 DNA in blood, faecal and tonsillar swabs collected from 12 pigs experimentally infected with PCV2 and sampled at selected time points post-infection. The PCR results were evaluated together with the presence of PMWS typical histopathological lesions and the presence of PCV2 antigen. PCV2 DNA was present in the blood of all 12 infected pigs at the end of the experiment and faecal and tonsillar swabs of 11 of the 12 pigs. The rate of PCR-positive serum and plasma samples was significantly higher in four pigs that showed virological and pathological evidence of PMWS, than in infected pigs without evidence of disease. In conclusion this study confirms that PCR cannot substitute for the traditional methods used for diagnosis of PMWS, however, PCR amplification of PCV2 DNA from serum or plasma could be a useful tool to support an early diagnosis of PMWS in live animals.


Asunto(s)
Infecciones por Circoviridae/veterinaria , Circovirus/genética , Reacción en Cadena de la Polimerasa/veterinaria , Enfermedades de los Porcinos/virología , Síndrome Debilitante/veterinaria , Animales , Antígenos Virales/análisis , Infecciones por Circoviridae/genética , Infecciones por Circoviridae/virología , ADN Viral/sangre , ADN Viral/genética , ADN Viral/metabolismo , Heces/virología , Técnica del Anticuerpo Fluorescente Indirecta/veterinaria , Histocitoquímica/veterinaria , Tonsila Palatina/virología , Distribución Aleatoria , Organismos Libres de Patógenos Específicos , Porcinos , Enfermedades de los Porcinos/sangre , Síndrome Debilitante/sangre , Síndrome Debilitante/virología
6.
Vet Pathol ; 41(5): 471-81, 2004 Sep.
Artículo en Inglés | MEDLINE | ID: mdl-15347819

RESUMEN

Tissue section replicates from lymphoid tissues and livers of gnotobiotic swine were examined by immunohistochemistry for the colocalization of porcine circovirus-2 (PCV-2) nucleocapsid and terminal deoxynucleotidyl transferase (TdT)-mediated incorporation of biotinylated nucleotides (UTP) onto the 3'-exposed hydroxyl groups (nick end labeling) nuclear deoxyribonucleic acid (TUNEL), a marker for apoptosis. Single- and dually stained replicates from uninfected controls, subclinically affected PCV-2-infected gnotobiotic pigs, PCV-2-infected piglets immunosuppressed with cyclosporine (Cys), and PCV-2-infected piglets with post-weaning multisystemic wasting syndrome (PMWS) were evaluated. Thymuses were used as positive controls for apoptosis absent PCV-2, tissue sections from dogs given hyperthermic stress were examined as positive controls for induced TUNEL. Tissues from heat-stressed dogs contained TUNEL-positive cell nuclei in both lymphoid tissues and liver, TUNEL was greatest shortly after the delivery of the hyperthermic insult. In uninfected control and subclinically affected PCV-2-infected gnotobiotic pigs, rare hepatocytes and lymphoid cells were TUNEL positive, the frequency of these was similar to that seen in uninfected controls. In PMWS-affected and Cys-treated PCV-2 piglets, the only consistent strongly positive TUNEL signal was contained within the cytoplasm of virus-positive phagocytic mononuclear cells. In phagocytes, some PCV-2 inclusions were TUNEL positive. Collectively, these data indicate that apoptosis is not the primary mechanism of lymphoid depletion and hepatocyte loss in PMWS. Apoptosis associated with systemic viral diseases may be attributable to pyrexia rather than direct or indirect effects of viruses on target cells.


Asunto(s)
Apoptosis/fisiología , Infecciones por Circoviridae/veterinaria , Circovirus/genética , Vida Libre de Gérmenes , Enfermedades de los Porcinos/patología , Enfermedades de los Porcinos/virología , Síndrome Debilitante/veterinaria , Animales , Infecciones por Circoviridae/patología , Hipertermia Inducida , Inmunohistoquímica , Etiquetado Corte-Fin in Situ , Leucocitos Mononucleares/patología , Hígado/patología , Sus scrofa , Síndrome Debilitante/patología , Síndrome Debilitante/virología
7.
Vet Microbiol ; 98(2): 159-63, 2004 Feb 04.
Artículo en Inglés | MEDLINE | ID: mdl-14741128

RESUMEN

Porcine circovirus-2 (PCV-2) is the necessary cause of post-weaning multisystemic wasting syndrome (PMWS) in swine; however, a variety of co-factors, including other infectious agents, are thought to be necessary in the full expression of disease. Porcine parvovirus (PPV) was found in the inoculum used in the first experiments to reproduce PMWS in gnotobiotic swine. Retrospective and prospective studies in the field and laboratory have demonstrated PCV-2 can act synergistically with PPV to enhance the severity of PMWS. PCV-2 has been shown to play a role in the porcine infectious disease complex (PRDC). Other co-infecting agents with PCV-2 in the lung include, porcine reproductive and respiratory syndrome virus (PRRSV), swine influenza virus (SIV) and Mycoplasma hyopneumoniae. Exposure of pregnant sows to PPV, PRRSV, or encephalomyocarditis virus may interact with PCV-2 infected foetuses. The severity of hepatic lesions in PCV-2 infected pigs may be enhanced by co-infection with agents such as swine hepatitis E virus and Aujezsky's disease virus. Additional studies are required to determine the mechanistic basis for the interaction of PCV-2 with other agents in the pathogenesis of the various clinical syndromes that have been associated with PCV-2 infection.


Asunto(s)
Infecciones por Circoviridae/veterinaria , Circovirus/crecimiento & desarrollo , Enfermedades de los Porcinos/virología , Síndrome Debilitante/veterinaria , Animales , Infecciones por Circoviridae/complicaciones , Infecciones por Circoviridae/inmunología , Circovirus/inmunología , Virus de la Influenza A/crecimiento & desarrollo , Virus de la Influenza A/inmunología , Mycoplasma hyopneumoniae/crecimiento & desarrollo , Mycoplasma hyopneumoniae/inmunología , Infecciones por Orthomyxoviridae/complicaciones , Infecciones por Orthomyxoviridae/inmunología , Infecciones por Orthomyxoviridae/veterinaria , Infecciones por Parvoviridae/complicaciones , Infecciones por Parvoviridae/inmunología , Infecciones por Parvoviridae/veterinaria , Parvovirus/crecimiento & desarrollo , Parvovirus/inmunología , Neumonía Porcina por Mycoplasma/inmunología , Síndrome Respiratorio y de la Reproducción Porcina/inmunología , Virus del Síndrome Respiratorio y Reproductivo Porcino/crecimiento & desarrollo , Porcinos , Síndrome Debilitante/complicaciones , Síndrome Debilitante/inmunología
8.
Vet Microbiol ; 98(2): 165-8, 2004 Feb 04.
Artículo en Inglés | MEDLINE | ID: mdl-14741129

RESUMEN

Porcine circovirus type 2 (PCV2) is now recognised as the causal agent of porcine multisystemic wasting syndrome (PMWS), an economically important wasting disease of young pigs [J. Vet. Diagn. Invest. 12 (2000) 3]. Gross lesions of PMWS include generalised lymphadenopathy, hepatitis, nephritis and pneumonia and typical histological lesions include lymphocytic depletion and multinucleated giant cell formation in lymph nodes, degeneration and necrosis of hepatocytes, and multifocal lymphohistocytic interstitial pneumonia. This communication will review the results of experimental infections of gnotobiotic (GN), colostrum-deprived (CD) and colostrum-fed (CF) pigs within our group, and elsewhere, with PCV2 and the conclusions that can be drawn from this work.


Asunto(s)
Infecciones por Circoviridae/veterinaria , Circovirus/crecimiento & desarrollo , Infecciones por Parvoviridae/veterinaria , Parvovirus Porcino/crecimiento & desarrollo , Enfermedades de los Porcinos/virología , Síndrome Debilitante/veterinaria , Animales , Infecciones por Circoviridae/complicaciones , Infecciones por Circoviridae/inmunología , Infecciones por Circoviridae/virología , Circovirus/inmunología , Calostro/inmunología , Vida Libre de Gérmenes , Infecciones por Parvoviridae/complicaciones , Infecciones por Parvoviridae/inmunología , Infecciones por Parvoviridae/virología , Parvovirus Porcino/inmunología , Porcinos , Síndrome Debilitante/complicaciones , Síndrome Debilitante/inmunología , Síndrome Debilitante/virología
9.
Vet Immunol Immunopathol ; 94(3-4): 149-61, 2003 Aug 15.
Artículo en Inglés | MEDLINE | ID: mdl-12909411

RESUMEN

Porcine circovirus type 2 (PCV2) nucleic acid and/or antigens are consistently observed in cells of monocytic morphology in lesions of pigs affected by post-weaning multisystemic wasting syndrome (PMWS). In this study, PCV2 antigen was detected in the cytoplasm of monocytes, pulmonary macrophages (PMs) and monocyte-derived macrophages exposed to the virus in vitro, by immunofluorescence analysis (IFA) and the phenotype of these cells confirmed by detection of monocytic cell surface markers using flow cytometry. Viral antigen was not observed in lymphocytic cells. Replication of the virus in PMs was investigated further by comparison to that observed in the continuous pig kidney cell line (PK15A) using quantitative virus titration, quantitative PCR and by the detection of double stranded DNA intermediates of viral replication by Southern blotting analyses. Although increases in viral DNA and levels of infectious virus progeny and the presence of replicative intermediates, indicative of viral replication, were observed in PK15A cells, no such changes were observed in PMs in spite of the fact that infectious virus, viral antigen and viral DNA persisted in the cells for at least the duration of the experiment. These results suggest that in vivo, monocytic cells may not represent the primary target for PCV2 replication.


Asunto(s)
Infecciones por Circoviridae/veterinaria , Circovirus/fisiología , Leucocitos Mononucleares/virología , Macrófagos Alveolares/virología , Enfermedades de los Porcinos/virología , Síndrome Debilitante/veterinaria , Animales , Antígenos Virales/inmunología , Southern Blotting/veterinaria , División Celular/inmunología , Infecciones por Circoviridae/inmunología , Infecciones por Circoviridae/virología , Circovirus/genética , Circovirus/inmunología , ADN Viral/química , ADN Viral/genética , Citometría de Flujo/veterinaria , Técnica del Anticuerpo Fluorescente Directa/veterinaria , Leucocitos Mononucleares/citología , Leucocitos Mononucleares/inmunología , Macrófagos Alveolares/citología , Macrófagos Alveolares/inmunología , Reacción en Cadena de la Polimerasa , Porcinos , Enfermedades de los Porcinos/inmunología , Replicación Viral , Síndrome Debilitante/inmunología , Síndrome Debilitante/virología
10.
Vet Microbiol ; 89(2-3): 97-114, 2002 Oct 22.
Artículo en Inglés | MEDLINE | ID: mdl-12243888

RESUMEN

Postweaning multisystemic wasting syndrome (PMWS) in swine is causally associated with the newly recognised pathogen, porcine circovirus type 2 (PCV2). In this study, 3-week-old SPF PCV2-seronegative piglets were inoculated intranasally with PCV2. The effect of immunostimulation on the induction of PMWS was investigated by immunisation with keyhole limpet hemocyanin (KLH) emulsified in incomplete Freunds adjuvant. The study was terminated 5 weeks after inoculation. While disease was not observed in the age-matched controls, two out of five non-immunised PCV2-infected piglets died on postinoculation day (PID) 21, and one was euthanized on PID 25 in moribund condition. These animals had appeared lethargic with persistent fever from PID 12 onwards. The euthanized pig appeared smaller than littermates and suffered from jaundice. At postmortem examination, gastric ulceration, icterus, and liver and thymus atrophy were observed. Furthermore, histological lesions of degenerating hepatocytes and hepatitis in combination with lymphoid depletion and syncytial cells in lymph nodes were consistent with the diagnosis of PMWS. One out of five immunostimulated PCV2-infected piglets was euthanized on PID 22 with convulsions after a period with wasting. This pig was lethargic from PID 14 onwards with persistent fever from PID 8 and transient dyspnoea. No differences in clinical signs, gross pathologic or histological findings were observed for the remaining non-immunostimulated and immunostimulated PCV2-infected piglets. All 10 PCV2-inoculated piglets seroconverted to PCV2 within 14 days after inoculation. By virus isolation, quantitative polymerase chain reaction (Q-PCR), and immunostaining of cryostat sections, it was demonstrated that lymphoid tissue contained abundant PCV2 antigen. Viral DNA load in serum samples was assessed by Q-PCR. All four PMWS-affected piglets had high levels of PCV2 DNA in serum, suggesting that there was a correlation between high levels of viral DNA in serum and the development of PMWS. In conclusion, infection with PCV2 caused PMWS in SPF piglets, however, the immunostimulation did not seem to play a critical role.


Asunto(s)
Infecciones por Circoviridae/veterinaria , Circovirus/inmunología , Enfermedades de los Porcinos/virología , Síndrome Debilitante/veterinaria , Adyuvantes Inmunológicos , Animales , Anticuerpos Antivirales/sangre , Infecciones por Circoviridae/inmunología , Infecciones por Circoviridae/patología , Infecciones por Circoviridae/virología , Circovirus/genética , ADN Viral/sangre , Hemocianinas/inmunología , Histocitoquímica/veterinaria , Hígado/patología , Hígado/virología , Tonsila Palatina/patología , Tonsila Palatina/virología , Reacción en Cadena de la Polimerasa/veterinaria , Distribución Aleatoria , Organismos Libres de Patógenos Específicos , Porcinos , Enfermedades de los Porcinos/inmunología , Enfermedades de los Porcinos/patología , Síndrome Debilitante/inmunología , Síndrome Debilitante/patología , Síndrome Debilitante/virología
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