First identification of porcine parvovirus 6 in North America by viral metagenomic sequencing of serum from pigs infected with porcine reproductive and respiratory syndrome virus.

Background: Currently, eight species in four genera of parvovirus have been described that infect swine. These include ungulate protoparvovirus 1 (classical porcine parvovirus, PPV), ungulate tetraparvovirus 2 (PPV3), ungulate tetraparvovirus 3 (which includes PPV2, porcine hokovirus, porcine partetravirus and porcine PARV4), ungulate copiparvovirus 2 (which includes PPV4 and PPV5), ungulate bocaparvovirus 2 (which includes porcine bocavirus 1, 2 and 6), ungulate bocaparvovirus 3 (porcine bocavirus 5), ungulate bocaparvovirus 4 (porcine bocavirus 7) and ungulate bocaparvovirus 5 (porcine bocavirus 3, 4-1 and 4-2). PPV6, the most recently described porcine parvovirus, was first identified in China in late 2014 in aborted pig fetuses.

Recognition of the different structural forms of the capsid protein determines the outcome following infection with porcine circovirus type 2.

Porcine circovirus type 2 (PCV2) capsid protein (CP) is the only protein necessary for the formation of the virion capsid, and recombinant CP spontaneously forms virus-like particles (VLPs). Located within a single CP subunit is an immunodominant epitope consisting of residues 169 to 180 [CP(169-180)], which is exposed on the surface of the subunit, but, in the structural context of the VLP, the epitope is buried and inaccessible to antibody. High levels of anti-CP(169-180) activity are associated with porcine circovirus-associated disease (PCVAD).