Detection and Characterization of Porcine Sapelovirus in Italian Pig Farms

Abstract

Porcine sapelovirus (PSV) belongs to the genus Sapelovirus of the family Picornaviridae. PSV infects pigs asymptomatically, but it can also cause severe neurologic, enteric, and respiratory symptoms or reproductive failure. Sapelovirus infections have been reported worldwide in pigs. The objective of this study was to investigate the presence and the prevalence of PSV in Italian swine farms in animals of different ages to clarify the occurrence of the infection and the genetic characteristics of circulating strains. In the present study, 92 pools of fecal samples, collected from pigs across three farms, were analyzed by Reverse Transcriptase-polymerase Chain Reaction-PCR (RT-PCR). Fecal pools from young growers (63/64) were found positive for Sapelovirus in all farms while detection in sows (4/28) was observed in only one farm. Phylogenetic analyses of the 19 partial capsid protein nucleotide sequences (VP1) (6-7 each farm) enable the classification of the virus sequences into three distinct clades and highlighted the high heterogeneity within one farm. The whole genome sequence obtained from one strain showed the highest correlation with the Italian strain detected in 2015. The study adds novel information about the circulation and heterogeneity of PSV strains in Italy and considering the movement of pigs across Europe would also be informative for other countries.

Keywords: Italy; PSV; porcine sapelovirus; swine.

Figure 1

Maximum likelihood phylogenetic tree built with GTR + G + I substitution model, by 1000 resampling, using 100 PSV partial VP1 sequences (790 nt) including the 19 PSV Italian strains reported in this study. Simian Sapelovirus strain was used as outgroup and bootstrap replicates >70% were reported. Each entry includes accession number and the country origin of strains.

Figure 2

Maximum likelihood phylogenetic tree built with GTR+G+I substitution model, by 1000 resampling, using 73 PSV complete genomes and the Italian complete genome SwPSV75BO2012 sequenced in this study, indicated in bold. Simian Sapelovirus strain was used as outgroup and bootstrap replicates >70% were reported. Each entry includes accession number, the country origin of strains, and collection date.