Pathogenic Characterization of a Porcine Circovirus Type 3 Isolate from Heilongjiang, China.

Menghang Wang,Fandan Meng,Ying Yu,Yabin Tu,Yu Wang,Hongliang Cui,Gang Wang,Xijun He,Jianan Wu,Shujie Wang,Xuehui Cai,Yandong Tang,Zhongjie Shi

doi:10.1155/2021/9434944

Abstract

The clinical outcome of porcine circovirus 3 (PCV3) infection is still controversial. Herein, a novel PCV3 isolate (PCV3-China/DB-1/2017) with the molecular characterization of 24A and 27K in the Cap protein was used to inoculate three-week-old cesarean-derived, colostrum-deprived piglets. The nine PCV3 DB-1 inoculated piglets exhibited no obvious clinical symptoms or macroscopic lesions. PCV3 displayed a broad histotropism, including the heart, liver, spleen, lung, kidney, brain, lymph nodes, and tonsil, and the lungs and lymph nodes contained a higher quantity of viral genomes compared to that of the other organs. From 7 days after PCV3 DB-1 inoculation, the piglets showed obvious IgG antibody responses against PCV3 rCap-VLPs. The cumulative results demonstrated that PCV3 trend to low pathogenicity.

Highlights

Porcine circovirus (PCV) is currently recognized as four types (i.e., PCV1, PCV2, porcine circovirus 3 (PCV3), and PCV4) [1,2,3,4,5,6,7], and PCV3 was recently recognized from a swine farm experiencing reproductive failure and porcine dermatitis and nephropathy syndrome- (PDNS-) like clinical signs in the United States in 2015 [3]
Phylogenetic characterization of ORF2 sequences showed that PCV3 DB-1 is the first isolation of alanine (A) and lysine (K) at positions 24 and 27 within the Cap protein in NCBI
PCV3 DB-1 shared a nucleotide identity of ~98.3-99.8% with PCV3 ORF2 sequences deposited in GenBank® (Figure 1(a))

Summary

Introduction

Porcine circovirus (PCV) is currently recognized as four types (i.e., PCV1, PCV2, PCV3, and PCV4) [1,2,3,4,5,6,7], and PCV3 was recently recognized from a swine farm experiencing reproductive failure and porcine dermatitis and nephropathy syndrome- (PDNS-) like clinical signs in the United States in 2015 [3]. Limited by viral isolation and prevalence in both diseased and healthy swine herds, the clinical relevance of PCV3 has being not clear and needs further study. To investigate the pathogenicity of PCV3 in piglets, in this study, we used a PCV3 isolate (PCV3-China/DB1/2017, MH286898) to inoculate three-week-old cesareanderived, colostrum-deprived (CDCD) piglets. Pathological changes, viral load, viral mRNA in the tissue, and antibodies against PCV3 rCap-VLPs were investigated. These results showed that piglets infected with PCV3 DB-1 developed no obvious clinical symptoms or macroscopic lesions. Histological pathological observation showed lymphocyte reduction and a few inflammatory cells infiltration in the lymph nodes, as well as thickened alveolar septum in the lungs. Our results provide a further explanation for the debatable clinical relevance of PCV3 infection

Materials and Methods

28 DPI Control

Results and Discussion