Characterization of porcine parvovirus type 2 (PPV2) which is highly prevalent in the USA

A novel porcine parvovirus designated as porcine parvovirus 2 (PPV2) was initially identified in Myanmar in 2001, in China during 2006-2007, and in Hungary in 2012. To investigate the presence and prevalence of PPV2 in the USA, a novel TaqMan® real-time PCR method was developed and used for a PPV2 survey using 483 lung samples, 185 fecal samples and 122 sera collected from pigs on 295 farms in 18 U.S. states. The overall prevalence of PPV2 was 20.7% (100/483) in lung samples and 7.6% (14/185) in fecal samples obtained from pigs of different age groups, and 1.6% (2/122) in sera or thoracic fluids obtained from neonatal pigs. Further genomic sequence comparison demonstrated that the 2011 U.S. PPV2 sequences have nucleotide identities of 95.4-97.7% with the 2006-2007 strains detected in China while the nucleotide identity was 94.7% with the 2001 strain detected in Myanmar, indicating persistent evolution of the virus. Phylogenetic and sequence homology analyses demonstrated a close relationship of PPV2 with members of the proposed genus 'PARV4-like virus', and the classification of PPV2 into this proposed genus is suggested.