Leng Chaoliang, Song Jiajing, Wang Jiabao, Zhai Hongyue, Ayra-Pardo Camilo, Cao Jiajia, Li Junjie, Zhao Yingying, Shi Hongfei, Li Dandan, Kan Yunchao, Yao Lunguang, Tian Zhijun
Henan Provincial Engineering and Technology Center of Animal Disease Diagnosis and Integrated Control, Henan Key Laboratory of Insect Biology in Funiu Mountain, Henan Province Engineering Research Center of Insect Bioreactor, China-UK International Joint Laboratory for Insect Biology of Henan Province, Nanyang Normal University, Nanyang, China.
Laboratory of Animal Parasitology and Pathology, CIIMAR/CIMAR LA, Interdisciplinary Centre of Marine and Environmental Research, University of Porto, Matosinhos, Portugal.
Front Vet Sci. 2025 Apr 22;12:1598383. doi: 10.3389/fvets.2025.1598383. eCollection 2025.
Porcine circovirus type 2 (PCV2) is a highly adaptable pathogen with significant implications for global swine health. In 2023, we investigated the prevalence and genetic variation of PCV2 in Henan Province, China, by analyzing blood and tissue samples from 380 pigs exhibiting clinical symptoms of PCV2 infection, including reproductive disorders and respiratory diseases. PCR analysis was used to detect PCV2, and viral sequences from 13 positive samples were characterized through phylogenetic and mutational analyses. PCV2 was detected in 56.58% (215/380) of samples. Nucleotide homology among newly identified PCV2 strains ranged from 95.14 to 100%, and 91.18-99.89% compared to 36 global reference strains. Phylogenetic analysis of the ORF2 gene encoding the viral capsid protein Cap identified PCV2a, PCV2b, and PCV2d subtypes, with most sequences clustering into three PCV2d subgroups (PCV2d-1, PCV2d-2, and PCV2d-3). Notably, the PCV2a strain HN230707 exhibited significant genetic divergence, forming an independent branch. Mutational analysis of the Cap protein revealed key amino acid substitutions in conformational epitope regions (T60S, R63T, N77D, V80L, L185M, A191K, and I200T), potentially contributing to immune evasion. Additionally, unique mutations in the nuclear localization signal and conformational epitope regions were identified in PCV2d subgroups. The emergence of genetically diverse PCV2 strains, particularly novel PCV2d sub-genotypes, raises concerns regarding their potential to evade vaccine-induced immunity. These findings highlight the importance of continuous molecular surveillance and the need for updated vaccine strategies to mitigate the impact of PCV2 on global swine health.
猪圆环病毒2型（PCV2）是一种适应性很强的病原体，对全球猪的健康有着重大影响。2023年，我们通过分析来自380头表现出PCV2感染临床症状（包括繁殖障碍和呼吸道疾病）的猪的血液和组织样本，调查了中国河南省PCV2的流行情况和基因变异。采用PCR分析检测PCV2，并通过系统发育和突变分析对13个阳性样本的病毒序列进行了特征分析。在56.58%（215/380）的样本中检测到了PCV2。新鉴定的PCV2毒株之间的核苷酸同源性范围为95.14%至100%，与36个全球参考毒株相比为91.18%至99.89%。对编码病毒衣壳蛋白Cap的ORF2基因进行系统发育分析，确定了PCV2a、PCV2b和PCV2d亚型，大多数序列聚为三个PCV2d亚组（PCV2d-1、PCV2d-2和PCV2d-3）。值得注意的是，PCV2a毒株HN230707表现出显著的基因差异，形成了一个独立的分支。对Cap蛋白的突变分析揭示了构象表位区域的关键氨基酸替换（T60S、R63T、N77D、V80L、L185M、A191K和I200T），这可能有助于免疫逃避。此外，在PCV2d亚组中还鉴定出了核定位信号和构象表位区域的独特突变。基因多样的PCV2毒株的出现，尤其是新型PCV2d亚基因型，引发了对其逃避疫苗诱导免疫潜力的担忧。这些发现凸显了持续进行分子监测的重要性以及更新疫苗策略以减轻PCV2对全球猪健康影响的必要性。
