Veterinary session

Porcine parainfluenza virus 1 (PPIV-1) also known as Porcine respirovirus 1 (PRV-1) belongs to the Paramyxoviridae family. Members of this family are known to cause various respiratory and neurological diseases in domestic and companion animal species. Additionally, some paramyxoviruses have zoonotic potential. PPIV-1 was first detected in rectal- and nasopharyngeal swabs obtained from slaughterhouse pigs in Hong Kong in 2013. Since its first detection, it has been identified in America, Asia and several European countries. Recent studies revealed that two separate PPIV-1 lineages might have independently evolved in Europe and North America, potentially making their way to Asia through infected animals. Although, information on the pathogenicity and global prevalence of the virus is sparse, it has been speculated to play a role in the porcine respiratory disease complex (PRDC). Previous experimental studies reported that PPIV-1 replicates in the porcine respiratory tract causing mild clinical disease or lesions.

The objective of this study was to estimate the prevalence and the genetic diversity of PPIV-1 in Hungarian pig farms and to report the presence of the virus in Slovakia for the first time in the country. Altogether 236 oral fluid samples were collected from 24 Hungarian and 2 Slovakian swine herds in a systematic way and tested by real-time RT-qPCR. During the time of the samplings the animals didn’t show any respiratory clinical symptoms in the tested herds. We detected the presence of the virus in 10 Hungarian herds (42%), and 1 Slovakian farm, which represents the first scientific evidence of the presence of PPIV-1 in the country. From 3 Hungarian and 1 Slovakian PPIV-1 positive herd nasal swab samples were collected cross-sectionally. The presence of the virus was detected in 34 (18,78%) of the 181 nasal swab samples. The highest prevalence of PPIV-1 was detected in 6-week-old pigs (40-75%) on Hungarian farms and in 2-week-old pigs on the Slovakian one (60%). The sequence of the F (fusion) gene was determined in seven cases and the comparative nucleotide sequence analysis indicated a similarity range of 93,53% to 94,65% between the Hungarian and Slovakian strains. All newly identified PPIV-1 strains were classified within Clade I, alongside with other European strains.

Further studies are needed in herds showing respiratory clinical symptoms to better understand the pathogenesis of the virus and to determine its potential role in PRDC.