There is evidence from experimental inoculations that persistent infections may be a feature of PCV2 (Bolin et al., 2001). Viral DNA was detected in some cesarian-derived colostrum-deprived (CDCD) PCV2-inoculated pigs up to 125 days post infection. To confirm the presence of infectious virus, viral isolation was done on homogenates of tissues that were PCR positive. Virus was isolated from all tissues in which viral DNA was detected (Bolin et al., 2001). Proof of persistent infection in the field is contradictory. PCV2 viremia was detected in the same animals for at least 8 weeks by PCR confirming persistence of PCV2 in pigs after natural exposure (Larochelle et al., 2003). Rodríguez-Arrioja et al. (2002) found a long duration of PCV2 viremia (up to 28 weeks of age) in a high percentage of naturally-PCV2-infected pigs on a PMWS-affected farm in Spain. PCV2 nucleic acids were detected in sera from 52.6% of 386 healthy slaughter-age pigs (Liu et al., 2002). In another survey however, researchers were unable to demonstrate microscopic lymphoid lesions or PCV2 nucleic acids at slaughter suggesting that pigs typically clear the virus (Quintana et al., 2001).
Bolin SR, Stoffregen WC, Nayar GPS, Hamel AL: Postweaning multisystemic wasting syndrome induced after experimental inoculation of cesarean-derived, colostrum-deprived piglets with type 2 porcine circovirus. J Vet Diagn Invest. 13:185-194, 2001
Larochelle R, Magar R, D'Allaire S: Comparative serologic and virologic study of commercial swine herds with and without postweaning multisystemic wasting syndrome. Can J Vet Res. 67:114-120, 2003
Liu Q, Wang L, Willson P, O'Connor B, Keenliside J, Chirino-Trejo M, Melendez R, Babiuk L: Seroprevalence of porcine circovirus type 2 in swine populations in Canada and Costa Rica. Can J Vet Res. 66:225-231, 2002
Quintana J, Segalés J, Rosell C, Calsamiglia M, Rodríguez-Arrioja GM, Chianini F, Folch JM, Maldonado J, Canal M, Plana-Durán J, Domingo M: Clinical and pathological observations on pigs with postweaning multisystemic wasting syndrome. Vet Rec. 149:357-361, 2001
Rodríguez-Arrioja GM, Segalés J, Calsamiglia M, Resendes AR, Balasch M, Plana-Durán J, Casal J, Domingo M: Dynamics of porcine circovirus type 2 infection in a herd of pigs with postweaning multisystemic wasting syndrome. Am J Vet Res. 63:354-357, 2002