High prevalence of porcine circovirus 3 in Hungarian pig herds: results
of a systematic sampling protocol
Abstract
Porcine circovirus type 3 (PCV3) is an emerging pathogen, that has been
reported worldwide in all ages of healthy and clinically ill pigs. The
presence of this virus in Hungary has been confirmed in a commercial
farm experiencing reproductive failures, but there were no data on the
circulation of PCV3 in the country. Here we report the prevalence and
the genetic diversity of PCV3 in Hungarian herds. For the estimation of
the prevalence altogether 1855 serum samples, 176 oral fluid and 97
processing fluid samples were collected in a systematic, cross-sectional
method from 20 large scale swine herds, and tested by real-time qPCR.
PCV3 was present in at least one type of diagnostic matrix in 19 out of
the 20 (95%) pig farms. The highest detection rates were observed in
the processing fluid samples (61%), but 41% of the oral fluid and 23%
of the serum samples were also positive. The virus was found in all age
groups and slightly more adult animals were infected than growing pigs,
but the viral burden was lower amongst them. Phylogenetic analysis of
nine full genomes, obtained from either the sampled herds or organ
samples of PCV3 positive carcasses showed high nucleotide identity
between the detected sequences, which all belonged to PCV3a genotype.
Our results indicate that PCV3 is widespread in Hungary but in most
cases the virus seems to circulate subclinically, infecting all age
groups and production phases without the presence of apparent clinical
disease.