Wang Dongliang, He Qing, Wang Naidong, Mai Jinhui
College of Biology, Hunan University, Changsha 410082, China.
Hunan Provincial Key Laboratory of Protein Engineering in Animal Vaccines, Laboratory of Functional Proteomics (LFP), Research Center of Reverse Vaccinology (RCRV), College of Veterinary Medicine, Hunan Agricultural University, Changsha 410128, China.
Animals (Basel). 2024 Jul 31;14(15):2222. doi: 10.3390/ani14152222.
Porcine parvovirus 7 (PPV7) was first discovered in swine in 2016, and PPV7 infection has been detected in aborted pig fetuses and in sows that experienced reproductive failure. The objective of this study was to report the prevalence and genetic characterization of PPV7 in Hunan, China. Seventy of the four hundred and twenty-two (16.6%) serum, semen, and tissue samples collected from pigs were positive for PPV7. One complete PPV7 strain and eighteen complete gene sequences were obtained; nucleotide and amino acid identity among the nineteen Cap sequences were 88.1-99.4% and 88.1-100%, respectively. They shared identity with previously discovered sequences ranging from 86.6 to 98.9% and 83.7 to 99.8% at the nucleotide- and amino acid-level, respectively. The phylogenetic tree analysis exhibited that PPV7 strains had two major groups based on the presence or absence of five amino acid (181-185) insertions on the Cap protein. Analysis of the Cap protein demonstrated that PPV7 Cap had significant variability, implying that PPV7 evolved at high substitution rates. Substantial variations of that PPV7 Cap may enable the emergence of newly mutated capsid profiles due to its viral adaptation to host responses. Furthermore, antigenic alteration owing to PPV7 Cap protein amino acid mutations at immune epitopes may enable viruses to escape from the host's immune system. This study determined the prevalence and genetic characteristics of PPV7 circulating in swine in Hunan, China, and provided the impetus and basis to further investigate the pathogenicity and epidemiology of PPV7.
猪细小病毒7型（PPV7）于2016年首次在猪身上被发现，并且在流产的猪胎儿和经历繁殖失败的母猪中检测到了PPV7感染。本研究的目的是报告中国湖南地区PPV7的流行情况和基因特征。从猪采集的422份血清、精液和组织样本中，有70份（16.6%）PPV7呈阳性。获得了1个完整的PPV7毒株和18个完整的基因序列；19个Cap序列之间的核苷酸和氨基酸同一性分别为88.1 - 99.4%和88.1 - 100%。它们与先前发现的序列在核苷酸水平和氨基酸水平上的同一性分别为86.6%至98.9%和83.7%至99.8%。系统发育树分析表明，基于Cap蛋白上是否存在5个氨基酸（181 - 185）插入，PPV7毒株有两个主要分支。对Cap蛋白的分析表明，PPV7 Cap具有显著变异性，这意味着PPV7以高替换率进化。PPV7 Cap的大量变异可能由于其病毒对宿主反应的适应性而导致新的衣壳突变体出现。此外，由于PPV7 Cap蛋白在免疫表位处的氨基酸突变引起的抗原改变可能使病毒逃避宿主免疫系统。本研究确定了在中国湖南猪群中循环的PPV7的流行情况和基因特征，并为进一步研究PPV7的致病性和流行病学提供了动力和基础。
