Antigenic characterisation of porcine circovirus 2 strains and outcome of experimental porcine circovirus 1 and 2 infections in porcine foetuses and in pigs

Porcine circoviruses (PCV1 and PCV2) are ubiquitious around the world. Although the genetic diversity among the PCV2 strains has been extensively studied, the antigenic diversity has been much less explored. PCV1 has been isolated from cases of reproductive failure and congenital tremor in newborn pigs. PCV2 is associated with Postweaning Multisystemic Wasting Syndrome (PMWS) and can cause reproductive failure. Despite the isolation of PCV1 and PCV2 from aborted/stillborn piglets and from cases of congenital tremors in newborn piglets, nothing is known about the outcome of experimental PCV1 infections in porcine foetuses and the outcome of experimental PCV2 (PCV2a or PCV2b) infections in porcine foetuses has only been examined with a restricted number of strains. The pathogenesis of PMWS is not fully understood yet and further research is needed. The absence or presence of low levels of neutralising antibodies in PMWS pigs has been reported and it may be hypothesized that this could be due to a certain immunotolerance upon an intrauterine infection with a less virulent PCV2 strain.