Detection and Genetic Characterization of Atypical Porcine Pestivirus in Piglets With Congenital Tremors in Southern China.

Yongsheng Xie,He Yan,Shaorong Lin,Danping Su,Liuming Wei,Junsen Feng,Dongsheng He,Weiyou Cai,Jinhui Li,Xiaoru Wang

doi:10.3389/fmicb.2019.01406

Abstract

Atypical porcine pestivirus (APPV) is an RNA virus newly discovered from swine in Asia, Europe, and the Americas. This novel virus has been confirmed as the cause of congenital tremor (CT) in piglets, which causes extensive economic losses to the swine industry. To investigate the genetic diversity and evolutionary relationship of APPV in China, 83 piglet samples with severe CT clinical signs were obtained from 12 commercial swine farms in 3 provinces of Southern China. RT-PCR revealed that the positive rates of APPV were as high as 100% (12/12) for the swine farms and 90.4% (75/83) for the samples. Subsequently, 21 positive samples and 3 positive samples were selected for partial E2 gene and complete polyprotein gene sequencing, respectively. Phylogenetic analysis showed that 62.5% of the sequences belonged to a novel APPV clade provisionally named genotype 3, which showed 81.0–82.1% sequence identity to genotypes 1 and 2. Amino acid sequence alignment showed that E2 protein of genotype 3 has three specific mutation sites, namely I19V, Y82F, and N107G. The results of the present study demonstrate that a novel APPV subgenotype, which is widely distributed in severe CT clinical samples in Southern China, was genetically diverse. We advocate for the inclusion of genotype 3 during revision of the APPV typing method.

Highlights

Pestiviruses are highly mutable RNA viruses comprising bovine viral diarrhea viruses 1 and 2, border disease virus, and classical swine fever virus (CSFV), which are responsible for huge economic losses in the swine industry worldwide (Postel et al, 2016, 2017; Smith et al, 2017; Zhou et al, 2019)
RT-PCR analysis of the 83 congenital tremor (CT) samples collected from the 12 commercial swine farms showed that 75 samples (90.4%) were positive for Atypical porcine pestivirus (APPV), and swine farm positive rates were as high as 100%, indicating that APPV was directly correlated with CT
In Austria, APPV infection directly led to a 10% increase in piglet mortality, and APPV antibodies could be detected in both sows and affected piglets; quantitative RT-PCR results showed that adult pigs had a high viral load in the saliva and semen (Schwarz et al, 2017)

Summary

Introduction

Pestiviruses are highly mutable RNA viruses comprising bovine viral diarrhea viruses 1 and 2, border disease virus, and classical swine fever virus (CSFV), which are responsible for huge economic losses in the swine industry worldwide (Postel et al, 2016, 2017; Smith et al, 2017; Zhou et al, 2019). In 2015, Hause et al (2015) using metagenomic sequencing, found a novel pestivirus, named atypical porcine pestivirus (APPV), in swine serum samples that were positive for porcine reproductive and respiratory syndrome virus Soon thereafter, this novel virus, which has caused extensive economic losses to the pig industry, was confirmed as the cause of congenital tremor (CT) in piglets in Netherlands, United States, Germany, Austria, China, Spain, Hungary, Brazil, and other countries These tremors gradually become more debilitating, causing difficulty in standing or a complete inability to walk, leading to starvation of affected piglets as they cannot stand to feed (de Groof et al, 2016; Schwarz et al, 2017; Yuan et al, 2017; Gatto et al, 2018b)

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