Search Results

Abstract

Objective—To determine the pattern of infection for porcine circovirus type 2 (PCV2) in a herd of pigs with postweaning multisystemic wasting syndrome (PMWS).

Animals—29 sows and 250 pigs.

Procedure—Blood samples were collected from all 3-, 7-, and 12-week old pigs and 59 pigs at 28 weeks of age. Pigs that died during the study were necropsied. Porcine parvovirus and PCV2 antibodies were assayed. A polymerase chain reaction (PCR) was used to detect PCV2 genome in serum of selected pigs.

Results—The PMWS started when pigs were 8 weeks old, with a prevalence of 30% in 8- to 10-weekold pigs. Eighty-three pigs died during the period between 3 and 12 weeks of age. Microscopic lesions consistent with PMWS were observed, and PCV2 nucleic acid was detected (50 of 68 pigs). Antibodies to PCV2 decreased from 3 to 7 weeks of age, increased at 12 weeks of age, and were maintained until 28 weeks of age. One sow had a positive result for PCR of serum. Nine, 37, and 8 pigs had PCV2 genome in serum obtained at 7, 12, and 28 weeks of age, respectively.

Conclusions and Clinical Relevance—Infection with PCV2 coincided with severe clinical signs; however, infected 28-week-old pigs did not have evidence of disease. Immunity declined over time in young pigs. A long duration of PCV2 viremia was apparent in a high percentage of infected pigs, which may affect transmission and persistence of the virus in a herd. (Am J Vet Res 2002;63:354–357).

Abstract

Objective—To determine whether correlations exist between viremia with porcine circovirus type 2 (PCV2) and serum antibody profiles and between detection of PCV2 in nasal cavities and viremia of pigs from farms with and without postweaning multisystemic wasting syndrome (PMWS).

Animals—495 pigs, ranging from the late nursery stage to the early grower-finisher stage of production.

Procedure—Serum antibodies to PCV2 were studied with an ELISA that detects the ORF2 viral protein. Nasal swab specimens and serum samples were tested with a PCV2-specific PCR assay.

Results—PCV2 DNA and serum antibodies to PCV2 were detected in pigs from all farms, although in different proportions. Overall, PCV2 DNA was detected in greater percentages in serum samples and nasal swab specimens of pigs from farms with PMWS. Although viral DNA was detected in both serum samples and nasal swab specimens, PCV2 detection in nasal swab specimens was higher than in serum samples of pigs from all farms. Serum antibodies to PCV2 were detected in a greater percentage of pigs from farms with PMWS, compared with farms without PMWS.

Conclusions and Clinical Relevance—A high prevalence of PCV2 infection was found in pigs from farms with and without PMWS. Besides the presence of PCV2, unknown additional factors may be necessary to induce the full expression of PMWS. ( Am J Vet Res 2004;65:88–92)

Summary

Enzyme histochemical and immunohistochemical techniques were used to examine palatine tonsils and aggregated lymphoid follicles (Peyer's patches) of the ileum in 6- to 9-day-old and in 6-month-old pigs. Histochemical techniques were used to detect α-naphthyl-acetate esterase (anae), α-naphthyl-butyrate esterase (anbe), β-glucuronidase, adenosine triphosphatase (ATPase), and acid phosphatase (AcP). Nonspecific esterases (anae, anbe) were detected in macrophages, T-cell area lymphocytes, eosinophils, fibroblastic reticular cells (frc), follicular dendritic cells (fdc), and interdigitating cells (idc). β-Glucuronidase reactivity was strong in macrophages, eosinophils, fdc, and idc, and weaker in frc. Adenosine triphosphatase reactivity was detected in B-cell area lymphocytes, fdc, frc, and idc. Cell types with acid phosphatase reactivity were macrophages, fdc, frc, and idc. Nonepithelial cells of tonsils and aggregated lymphoid follicles of the ileum had similar enzymatic reactions. In Peyer's patches, however, epithelial cells were positive for all enzymes studied; in tonsils, only nonspecific esterases were detected. Immunoperoxidase techniques were used to detect S-100 protein and cytoplasmic immunoglobulins (IgG, IgM, and IgA). The S-100 protein was detected in lymphocytes, fdc, and frc of tonsils and Peyer's patches; in tonsillar epithelial and endothelial cells; and in idc of Peyer's patches. Cytoplasmic immunoglobulins were detected in lymphoblastoid and plasmacytoid cells of follicles and diffuse lymphoid tissue in both organs and in ileal epithelial cells. Compared with those of 6-month-old pigs, cells of 6- to 9-day-old pigs stained less intensely by all enzyme histochemical techniques, and fewer cells were reactive for immunoglobulins.