The PCV2 virus
As investigations continue the PCV2 virus becomes more complicated.
There are three strains of PCV2 referred to as a,b and c. Type a is also called 2 in Europe and b is called 1.
PCV2b is the 331 RFPL pattern recognized in Canada in 2005. However, studies into any differences in pathogenesis are ongoing and inconclusive.
All three strains occur in Australia where PMWS is not seen as a herd condition.
Individual pigs are recognised as having PCVAD.
The viral capsid tree for Australia appears as:
The presence of all three strains of PCV2 in Australia which has not imported any live pig products since 1992 throws into question the relevance of these strains in PMWS.