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


METHODS
29 sows and 250 pigs.


METHODS
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-week-old 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
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.
Rodríguez-Arrioja
Gabriela M
GM
Centre de Recerca en Sanitat Animal, Departament de Sanitat i d'Anatomia Animals, Universitat Autònoma de Barcelona, Bellaterra, Spain.
Segalés
Joaquim
J
Calsamiglia
Maria
M
Resendes
Ana R
AR
Balasch
Monica
M
Plana-Duran
Juan
J
Casal
Jordi
J
Domingo
Mariano
M
D000818:Animals; D000914:Antibodies, Viral / Q000097:blood; D018173:Circoviridae Infections / Q000097:blood / Q000276:immunology / Q000662:veterinary* / Q000821:virology; D017925:Circovirus / Q000235:genetics / Q000254:growth & development*; D004279:DNA, Viral / Q000737:chemistry / Q000235:genetics; D005260:Female; D017403:In Situ Hybridization; D008221:Lymphoid Tissue / Q000473:pathology / Q000821:virology; D008297:Male; D016133:Polymerase Chain Reaction / Q000662:veterinary; D013030:Spain; D013552:Swine; D013553:Swine Diseases / Q000276:immunology / Q000473:pathology / Q000821:virology*; D019282:Wasting Syndrome / Q000097:blood / Q000276:immunology / Q000662:veterinary* / Q000821:virology
D000914:Antibodies, Viral; D004279:DNA, Viral