Comparative Prevalence Estimation and Phylogenetic Analysis of Novel Porcine Parvoviruses (PPV2–7) in Hungarian Pig Herds

To date, seven novel parvoviruses have been identified in pigs and designated as porcine parvovirus 2–7 (PPV2–7). The presence of these emerging viruses has been reported in several countries around the world, although their pathogenic role and clinical and economical relevance are largely unknown. Here, we report the estimated prevalence and genetic diversity of novel PPV2–7 in Hungarian pig herds and the detection of these viruses in two Slovakian pig farms. For the comparative prevalence estimation, 2505 serum samples from different age groups, 218 oral fluid samples, and 111 processing fluid samples were collected from 26 large-scale Hungarian farms according to a systematic, cross-sectional sampling protocol. All samples were tested by real-time quantitative polymerase chain reaction (qPCR), and the presence of at least one PPV was detected in 24 of the 26 (92%) Hungarian and both Slovakian farms, suggesting high levels of subclinical circulation in most herds. The estimated PPV2–7 prevalence in Hungary varied from 50% to 89%, with PPV4 being the least and PPV2 being the most prevalent virus. The highest detection rates were observed in oral fluid samples, indicating that this sample type is most suitable for screening PPVs, but all viruses were also detected in serum samples and processing fluids. All novel PPVs were most frequently detected in the serum samples of weaned pigs and fatteners, with slightly higher viral burden in the younger age groups. These results may suggest an age-related susceptibility, which could play a significant role in the epidemiology of these viruses, impacting herd health and productivity.