Epidemiology and Evolution of Emerging Porcine Circovirus-like Viruses in Pigs with Hemorrhagic Dysentery and Diarrhea Symptoms in Central China from 2018 to 2021.

Kankan Yang,Jian Tu,Ying Shao,Kaiyuan Ji,Qi Liu,Menghuan Zhang,Kezong Qi,Xiangjun Song,Yueqiao Liang,Wuyin Zhang,Yingli Cao

doi:10.3390/v13112282

Abstract

Porcine circovirus-like virus (PCLV) is a type of circular Rep-encoding single-stranded DNA virus and may be associated with the development of diarrheal symptoms in pigs. In this study, we retrospectively analyzed three years of past cases in Anhui, China, and reported a case of hemorrhagic enteritis and death in a pregnant sow possibly caused by PCLV. In addition, we analyzed the evolutionary characteristics of PCLV and found that mutation, recombination and selective pressure all played an important role in the evolution of PCLV. We identified N15D and T17S as well as L56T, T58R, K59Q, M62R, L75I and R190K mutations in two different branches, and we noted recombination events in the Rep of a group of Chinese strains. Analysis of selection pressure revealed that PCLV gained more positive selection, indicating that the virus is in a continuous evolutionary state. The PR2 plot, ENC-plot and neutrality analysis showed a greater role of natural selection than that of mutational pressure in the formation of codon usage patterns. This study is the first to identify PCLV in sows with hemorrhagic dysentery and death, and it provides new epidemiological information on PCLV infection in pigs in China.

Highlights

The first eukaryotic CRESS DNA viruses were not discovered until the 1970s, symptoms consistent with CRESS DNA virus infections were described more than a thousand years ago in plants [3]
MZ773067) from farm A was a fecal sample from a weaned piglet that showed signs of diarrhea, and Porcine circovirus-like virus (PCLV) was detected mixed with porcine astrovirus and porcine epidemic diarrhea virus (PEDV)
The age of the pig from which sample 2 was collected (AH-25, accession number: MZ773068) on farm B could not be determined, and the fecal sample was co-infected with porcine circovirus (PCV)-2 and porcine parvovirus (PPV)

Summary

Introduction

Circular Rep-encoding single-stranded DNA (CRESS DNA) viruses form a highly diverse group of small viruses that have been found worldwide in prokaryotic, eukaryotic and even environmental samples [1,2]. The first eukaryotic CRESS DNA viruses were not discovered until the 1970s, symptoms consistent with CRESS DNA virus infections were described more than a thousand years ago in plants [3]. DNA viruses are divided into seven families: Bacilladnaviridae, Nanoviridae, Smacoviridae, Geminiviridae, Genomoviridae, Redondoviridae and Circoviridae [4]. Members of the Circoviridae, Smacoviridae and Redondoviridae families are known to infect animals, including mosquitoes, rats, bats, ducks, cattle, pigs, dogs, humans, turkeys, and forest musk deer [5,6,7,8]. The genome structure of members of this family contains only one open reading frame (ORF), encoding only the Rep, rather than containing two ORFs as in the case of members of other families [2,9,10]

Methods

Results

Conclusion