Detection and genotyping of Porcine circovirus 2 (PCV-2) and detection of Porcine circovirus 3 (PCV-3) in sera from fattening pigs of different European countries.

PCV-2 is considered one of the most economically important viral agents in swine worldwide. Recently, PCV-3 has been found in pigs affected by different disorders as well as in healthy animals. The objective of this epidemiological work was to describe the frequency of detection of PCV-2 and PCV-3 in pig farms of 9 European countries. Moreover, a second aim was to assess the most frequent PCV-2 genotypes found in the studied farms. Sera from 5 to 10 pigs per farm were collected from 2 to 11 farms per studied country. A total of 624 sera of fattening pigs (10 to 25 week-old) from 64 farms from Spain (n=11), Belgium (n=10), France (n=8), Germany (n=8), Italy (n=7), Denmark (n=8), The Netherlands (n=5), Ireland (n=5) and Sweden (n=2) were analysed by conventional PCR. In addition, one or two PCV-2 positive samples per farm were genotyped by sequencing the ORF2 gene. PCV-3 PCR positive samples with relatively low Ct values were also sequenced and phylogenetically analysed. PCV-2 DNA was detected in pig sera from all European tested countries, but Sweden. A total of 132 out of 624 (21%) sera were positive for PCV-2 PCR, corresponding to 30 out of the 64 (47%) tested farms. PCV-3 DNA was detected in 52 out of 624 (8%) sera, corresponding also to 30 out of the 64 (47%) studied farms from all tested countries. A total of 48 PCV-2 PCR positive samples were successfully sequenced and genotyped, being PCV-2d the most frequently genotype found (n=28), followed by PCV-2b (n=11) and PCV-2a (n=9). These results pointed out PCV-2d as the most prevalent genotype currently in Europe. The PCV-3 phylogenetic analysis showed high identity (>98%) among sequences from all the analysed countries. The relatively low co-infection (3%), likely suggest an independent circulation patterns of PCV-2 and PCV-3.