Viral Disease Division, Animal and Plant Quarantine Agency, 177, Hyeoksin 8-ro, Gimcheon-si, Gyeongsangbuk-do, 39660, Republic of Korea.
KBNP, 415, Heungan-daero, Dongan-Gu, Anyang-si, Gyeonggi-do, 14059, Republic of Korea.
BMC Vet Res. 2020 Sep 14;16(1):334. doi: 10.1186/s12917-020-02549-3.
Porcine circovirus type 2 (PCV2) is a small single-stranded DNA virus and a primary cause of PCV-associated diseases (PCVAD) that result insubstantial economic loss for swine farms. Between 2016 and 2018, PCV2 field viruses were isolated from PCVAD-affected swine farms in South Korea and investigated for genetic and antigenic heterogeneity.
The genetic analysis of ORF2 showed that the genotype of the Korean PCV2 field isolates has been rapidly shifted from PCV2a or 2b to mutant PCV2b known as PCV2d with 82.6 to 100% amino acid sequence similarity. PCV2-specific monoclonal antibodies (mAbs) demonstrated variable antigen-binding activity to four representative Korean PCV2 field isolates [QIA215 (PCV2a), QIA418 (PCV2b), QIA169 (PCV2d), and QIA244 (PCV2d)] without genotype specificity, and one mAb showed neutralization activity to QIA215. In a cross-virus neutralization assay using anti-PCV2 sera of pigs and guinea pigs injected with a commercial vaccine and the Korean PCV2 field isolates, the anti-porcine sera of a commercial vaccine had high neutralization activity against QIA215 and QIA418 with statistically lower activity against PCV2d viruses. Anti-guinea pig sera of QIA215, QIA418, QIA169, and a commercial vaccine had high neutralization activity against all of the viruses with significantly lower activity against QIA244. Importantly, anti-guinea pig sera of QIA244 had high neutralization activity against all of the viruses.
This study confirmed genetic and antigenic diversity among recent PCV2 field isolates in Korean swine farms, and the strain-based difference in virus neutralization capability should be considered for more effective control by vaccination.
猪圆环病毒 2 型（PCV2）是一种小型单链 DNA 病毒，是导致与 PCV 相关疾病（PCVAD）的主要原因，给养猪场造成了巨大的经济损失。2016 年至 2018 年，从韩国受 PCVAD 影响的养猪场中分离到 PCV2 田间病毒，并对其遗传和抗原异质性进行了调查。
ORF2 的遗传分析表明，韩国 PCV2 田间分离株的基因型已从 PCV2a 或 2b 快速转变为具有 82.6%至 100%氨基酸序列相似性的突变型 PCV2b，称为 PCV2d。PCV2 特异性单克隆抗体（mAb）对四个代表性的韩国 PCV2 田间分离株[QIA215（PCV2a）、QIA418（PCV2b）、QIA169（PCV2d）和 QIA244（PCV2d）]表现出可变的抗原结合活性，没有基因型特异性，并且一种 mAb 对 QIA215 具有中和活性。在使用抗 PCV2 血清对猪和豚鼠进行的交叉病毒中和试验中，用商业疫苗接种的猪和豚鼠的抗血清对 QIA215 和 QIA418 具有高中和活性，对 PCV2d 病毒的活性较低。QIA215、QIA418、QIA169 和商业疫苗的抗豚鼠血清对所有病毒均具有高中和活性，对 QIA244 的活性明显较低。重要的是，QIA244 的抗豚鼠血清对所有病毒均具有高中和活性。
本研究证实了韩国养猪场近期 PCV2 田间分离株的遗传和抗原多样性，在疫苗接种方面，应考虑基于毒株的病毒中和能力差异，以进行更有效的控制。
