猪圆环病毒4型(PCV4)是一种新兴的病毒,在中国和韩国几个省份的猪群中检测到PCV4基因组DNA和特异性抗体。尽管该病毒于2019年在湖南首次发现,中国,回顾性研究提示早在2008年采集的血清样本PCV4抗体呈阳性.仅PCV4感染或与其他病原体共同感染与几种临床表现相关。但其发病机制尚待确定。本综述的目的如下:(1)通过评估猪群中循环的PCV4菌株的进化动态和遗传多样性来表征PCV4流行病学;(2)重建计算机3D模型以分析PCV4Cap特性;(3)并总结与PCV4相关的临床病理表现的当前证据。PCV4的起源显然与其他PCV不同,基于系统发育树的分析。值得注意的是,PCV4与水貂圆环病毒有着古老的共同祖先。此外,PCV4Cap第27位的氨基酸残基是区分PCV4a(27S)和PCV4b(27N)的关键基准,基于目前可用的PCV4菌株,并且该残基的变化可能会改变Cap的抗原性。此外,PCV4的衣壳表面具有极性残基增加的特征,与PCV2相比,这增加了PCV4可能靶向带负电荷的宿主受体以促进病毒感染的可能性。需要进一步的研究,包括病毒分离和培养,并对PCV4在猪群中的分子流行病学和遗传多样性进行了更详细的表征。
Porcine circovirus type 4 (
PCV4) is a newly emerging virus, with both
PCV4 genomic DNA and specific antibodies detected in swine herds in several provinces in China and South Korea. Although the virus was first identified in 2019 in Hunan, China, retrospective research suggests that serum samples collected as early as 2008 were positive for
PCV4 antibody. Infections with only PCV4 or co-infections with other pathogens have been associated with several clinical manifestations, but its pathogenesis remains to be determined. The purpose of this review was the following: (1) to characterize PCV4 epidemiology by assessing evolutionary dynamics and genetic diversity of PCV4 strains circulating in swine herds; (2) to reconstruct a computerized 3D model to analyze
PCV4 Cap properties; (3) and to summarize the current evidence of
PCV4-associated clinical-pathological manifestations. The origin of
PCV4 is apparently distinct from other PCV, based on analysis of phylogenetic trees. Of note,
PCV4 shares an ancient common ancestor with mink circoviruses. Furthermore, the amino acid residue at position 27 of the PCV4 Cap is a key benchmark to distinguish PCV4a (27S) from PCV4b (27 N), based on PCV4 strains currently available, and variation of this residue may alter Cap antigenicity. In addition, the capsid surface of PCV4 has characteristics of increased polar residues, compared to PCV2, which raises the possibility that PCV4 may target negatively charged host receptors to promote virus infection. Further studies are required, including virus isolation and culture, and more detailed characterization of molecular epidemiology and genetic diversity of PCV4 in swine herds.