Influence of specific maternal antibodies on the development of experimental infection with porcine circovirus type 2 (PCV2)

Porcine circovirus type 2 (PCV2) infection is now recognized as the major factor in the development of postweaning multisystemic wasting syndrome (PMWS), that affect pigs predominantly between 5 and 15 weeks of age. Antibody to PCV2 has been demostrated in a very high percentage of pig sera tested troughout the world, and has been detected retrospectively to, at least, 1969. Furthermore, though PCV2 infection has been consistently detected in pigs with PMWS, it does not inevitably lead to clinical symptoms. So it has been concluded that sub-clinical infections with PCV2 are common events in pigs population. Concomitant infections with porcine parvovirus (PPV) or porcine respiratory and reproductive syndrome virus (PRRS) and the activation of the immune system induced by \nvaccinations are considered important co-factors in the pathogenesis of PCV2-associated PMWS. Maternal serum antibodies towards PCV2 can also influence the outcome of the infection (1), and experimental PCV2 infections of seropositive conventional piglets often failed to reproduce the disease. PCV2 infection is thought to be necessary but not sufficient to determine the full expression of PMWS (6). The objective of this study was \nto evaluate the clinical and pathological consequences of an infection with PCV2 in combination with PPV in 3-week-old, conventional, colostrum-fed pigs with different levels of maternal PCV2 serum antibodies.