College of Life Sciences of Longyan University, Longyan, China.
Fujian Provincial Key Laboratory for the Prevention and Control of Animal Infectious Diseases and Biotechnology, Longyan, China.
Transbound Emerg Dis. 2019 Nov;66(6):2496-2506. doi: 10.1111/tbed.13307. Epub 2019 Aug 5.
Porcine circovirus type 2 (PCV2) has been causing huge economic losses in Chinese swine herds since it was first identified in China in 1999. Genotypes of PCV2 except for PCV2c coexist in swine herds in China, which may facilitate virus recombination. In the current study, six novel PCV2 strains were detected in China, and these strains shared high nucleotide similarity of the Rep gene with the PCV2c strain DK1987PMWSfree and high homology of the Cap gene with PCV2d. Genome sequence analysis revealed that the complete genomes of these strains were 1767 nucleotides (nt) in length and shared 99.8%-99.9% nucleotide identity with each other and 91.7%-98.7% with representative strains. Phylogenetic analysis, sequencing analysis, base-by-base comparisons and comprehensive recombination analysis demonstrated that these six strains originated from recombination within the Rep gene between PCV2c and PCV2d strains. Surprisingly, further investigation through theoretical recombination analysis of Chinese PCV2 GenBank sequences showed that these novel patterns of recombinant PCV2 strains have been generated since 2010. Collectively, our findings provide additional evidence of inter-genotypic recombination of PCV2.
自 1999 年在中国首次发现以来，猪圆环病毒 2 型（PCV2）一直给中国的养猪业造成巨大的经济损失。除了 PCV2c 型以外，其他基因型的 PCV2 在中国猪群中共同存在，这可能促进了病毒重组。在本研究中，在中国检测到了 6 种新型 PCV2 毒株，这些毒株的 Rep 基因与 PCV2c 型 DK1987PMWSfree 株具有很高的核苷酸相似性，Cap 基因与 PCV2d 型具有很高的同源性。基因组序列分析显示，这些毒株的完整基因组长度为 1767 个核苷酸（nt），彼此之间的核苷酸同一性为 99.8%-99.9%，与代表性毒株的核苷酸同一性为 91.7%-98.7%。系统进化分析、测序分析、逐碱基比较和综合重组分析表明，这 6 个毒株来源于 PCV2c 和 PCV2d 株之间 Rep 基因内的重组。令人惊讶的是，通过对中国 PCV2 GenBank 序列的理论重组分析进一步研究表明，这些新型重组 PCV2 毒株自 2010 年以来就已经产生。总的来说，我们的研究结果提供了 PCV2 发生基因间重组的额外证据。
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