Detection of atypical porcine pestivirus in Swedish piglets with congenital tremor type A-II

Abstract

Background: Congenital tremor (CT) type A-II is a neurological disorder characterized by tremor of the head and body of newborn piglets. The suggested causative agent of the disease is the recently found atypical porcine pestivirus (APPV). The virus has been detected in piglets suffering from congenital tremor in central Europe, South and North America and in China but no studies has so far been performed in the Nordic countries. The overarching goal of this study was to investigate if APPV is present in the brain tissue of Swedish piglets suffering from congenital tremor. From June 2017-June 2018, 15 piglets from four Swedish farms with ongoing outbreaks of congenital tremor and 13 piglets with splay leg originating from four different farms, were investigated for presence of APPV RNA in brain tissue. Matched healthy control piglets (n = 8) were also investigated. Two APPV-specific RT-qPCR methods targeting the NS3 and NS5B region, respectively, were used. A retrospective study was performed on material from Swedish piglets with congenital tremor sampled in 2004 (n = 11) and 2011/2012 (n = 3) using the described APPVspecific RT-qPCR methods. The total number of piglets with signs of CT in this study was 29. Results: Atypical porcine pestivirus-RNA was detected in 93% (27/29) of the piglets suffering from congenital tremor. All piglets with congenital tremor from 2004 (n = 11) and 2012 (n = 3) were PCR-positive with respect to APPV, whereas, all of the healthy controls (n = 11) were negative. The piglets with congenital tremor sampled 2017-2018 had an odds ratio of 91.8 (95% CI 3.9128 to 2153.7842, z = 2.807, P = 0.0050) to test positive for APPV by qRT-PCR compared to the healthy piglets (Fishers exact test p < 0.0001). These findings make it interesting to continue investigating APPV in the Swedish pig-population. Conclusion: This is the first description of atypical porcine pestivirus in piglets suffering from congenital tremor type A-II in Sweden and the Nordic countries. The virus has been present in the Swedish pig population since at least 2004.

Detection and genetic analysis of a novel atypical porcine pestivirus from piglets with congenital tremor in Japan

“…The mortality rates of CT clinical disease caused by APPV are generally low, and the economic losses remain unknown; however, severely affected piglets with CT may die due to colostrum intake difficulties and starvation, resulting in a higher pre-weaning mortality rate (Pan et al, 2019a;Stenberg et al, 2020). Clinical signs of CT have been observed since 15 years ago on the farm where Anna/2020 was detected, so the presence of APPV in the piglets might have been causing economic losses for the farm.…”

“…APPV was first discovered from the serum of a pig without clinical symptoms in the United States (Hause et al, 2015). Since then, APPVs have been found from pigs and wild boars with or without CT worldwide on four continents, and genomic sequence diversity among APPVs has been reported (Beer et al, 2017;Cagatay et al, 2018;Chen et al, 2019;Choe et al, 2020;Colom-Cadena et al, 2018;de Groof et al, 2016;Dénes et al, 2018;Dessureault et al, 2018;Gatto et al, 2018;Mósena et al, 2018;Muñoz-Gonzalez et al, 2017;Pan et al, 2019b;Possatti et al, 2018;Postel et al, 2016Postel et al, , 2017Schwarz et al, 2017;Shen et al, 2018;Sozzi et al, 2019;Stenberg et al, 2020;Xie et al, 2019;Yan et al, 2019;Yuan et al, 2017;Zhang et al, 2017;Zhang et al, 2019;Zhou et al, 2019). However, genome sequence data of APPV have not been reported from Japan.…”

Atypical Porcine Pestiviruses: Relationships and Conserved Structural Features

“…APPV has been isolated in all continents, apart from Africa and Australia ( Figure 3 ). In Europe, APPV in domestic pigs has been documented in Austria [ 13 ], Germany [ 11 , 14 , 15 ], Hungary [ 16 ], Italy [ 14 , 17 ], Serbia [ 14 ], Spain [ 18 ], Sweden [ 19 , 20 ], Switzerland [ 14 , 21 ] and the United Kingdom [ 14 , 22 ] and in wild boar in Germany [ 23 ] and Spain [ 24 ]. In the Americas, reports of APPV infection exist from Brazil [ 25 , 26 ], Canada [ 27 ] and the USA [ 7 , 8 , 28 ].…”

Detection of Atypical Porcine Pestivirus in Piglets from Danish Sow Herds

“…Due to this relatively new discovery, and since this virus does not seem to cause losses at the same level as, e.g., porcine reproductive and respiratory syndrome virus and porcine circovirus, little is known about its epidemiological properties. Recent publications show that the virus has been detected in several other countries, including Austria [ 3 ], Brazil [ 4 ], Canada [ 5 ], China [ 6 ], Denmark [ 7 ], Germany [ 8 , 9 ], Hungary [ 10 ], Italy [ 11 ], Korea [ 12 ], the Netherlands [ 13 ], Spain [ 14 ], Sweden [ 15 , 16 ], Switzerland [ 2 ], Serbia [ 9 ], Taiwan [ 9 ], the United Kingdom [ 9 ], and the United States [ 1 , 17 ]. The virus has a high genetic variability between countries as well as within countries [ 4 , 9 , 18 , 19 ], and recombination between APPV strains has recently been reported in China [ 18 ].…”