Detection and phylogenetic characterization of atypical porcine pestivirus strains in Hungary.

Atypical porcine pestivirus (APPV) is a recently identified RNA virus within the Flaviviridae family, causing congenital tremor (CT) in the piglets of infected sows. We have investigated 25 cases of CT from 2005, 2007, 2010 and 2016-2018, originating from six different farms. RT-PCR has been performed on these samples and all of the affected piglets were positive to APPV. Our phylogenetic analysis showed that Hungarian strains show a high degree of variability and are clustered into five distinct lineages. Four strains originating from one farm have shown exceptional similarity (99.9%) to an Austrian sequence, whereas another one from a different herd was grouped close to a Chinese strain (96.4% similarity). Our results suggest multiple events of introduction of the virus from various sources into Hungary. This is the first report of the presence and clinical relevance of APPV in the Hungarian pig population.