Department of Veterinary Pathology, College of Veterinary Sciences & Animal Husbandry, Central Agricultural University, Selesih, Aizawl, Mizoram 796014, India.
Department of Veterinary Pathology, College of Veterinary Sciences & Animal Husbandry, Central Agricultural University, Selesih, Aizawl, Mizoram 796014, India.
Infect Genet Evol. 2021 Jun;90:104775. doi: 10.1016/j.meegid.2021.104775. Epub 2021 Feb 20.
The molecular genetics of fourteen Porcine Circovirus 2 (PCV2) isolates from non-vaccinated pigs that died of porcine circovirus associated disease (PCVAD) between 2012 and 2019 in the Mizoram state of North East India, was studied. The PCVAD in these pigs, that had shown characteristic clinical signs and lesions associated with post-weaning multi-systemic wasting syndrome and reproductive failure was confirmed with detection of PCV2 DNA in the tissue samples. Complete viral genomes of these fourteen field isolates were sequenced following in house developed overlapping PCR. The multiple sequence alignment of viral capsid proteins or the open reading frame 2 (ORF2) sequences showed highly conserved residues known for antibody recognition and genotype specificity, however, variations were noticed in the amino acid residues previously known as important for in vitro replication of PCV2. The phylogenetic analyses based on the complete genome sequences enabled identification of genotype PCV2g (9/14, 64.29%) for the first time in India along with genotypes PCV2d (3/14, 21.43%) and PCV2b (2/14, 14.29%). Further, recombination analyses showed evidence for recombination between the genotypes 2b, 2g and 2d. This is the first report on the prevalence of genotype PCV2g and natural inter-genotypic (2g-2b, 2g-2d and 2d-2g) recombinants in India. The findings indicate a non-vaccine driven, natural genotypic shift and signify the need for routine PCV2 surveillance and genotyping. Our analyses also provide a solid ground for future studies to understand the consequences of multiple PCV2 genotypes within a pig population with respect to vaccination, diagnostics and emergence of new genotypes.
对来自印度东北部米佐拉姆邦的 2012 年至 2019 年间因猪圆环病毒相关疾病（PCVAD）而死亡的未接种疫苗猪的 14 株猪圆环病毒 2 型（PCV2）分离株的分子遗传学进行了研究。这些猪出现了与断奶后多系统消耗综合征和生殖失败相关的特征性临床症状和病变，通过组织样本中 PCV2 DNA 的检测证实了 PCVAD 的存在。使用内部开发的重叠 PCR 对这 14 个田间分离株的完整病毒基因组进行了测序。病毒衣壳蛋白或开放阅读框 2（ORF2）序列的多序列比对显示了高度保守的残基，这些残基已知可被抗体识别并具有基因型特异性，但在先前被认为对 PCV2 体外复制重要的氨基酸残基中也发现了变异。基于全基因组序列的系统发育分析首次在印度鉴定出基因型 PCV2g（9/14，64.29%），同时还鉴定出基因型 PCV2d（3/14，21.43%）和 PCV2b（2/14，14.29%）。此外，重组分析表明 2b、2g 和 2d 基因型之间存在重组证据。这是印度首次报道基因型 PCV2g 和自然基因间（2g-2b、2g-2d 和 2d-2g）重组的流行情况。研究结果表明，这是一种非疫苗驱动的自然基因型转变，并表明需要进行常规的 PCV2 监测和基因分型。我们的分析还为未来的研究提供了坚实的基础，以了解在接种疫苗、诊断和新基因型出现的情况下，猪群中多种 PCV2 基因型的后果。
