Nguyen Van-Giap, Do Hai-Quynh, Huynh Thi-My-Le, Park Yong-Ho, Park Bong-Kyun, Chung Hee-Chun
Department of Veterinary Microbiology and Infectious Diseases, Faculty of Veterinary Medicine, Vietnam National University of Agriculture, Hanoi, Vietnam.
Department of Veterinary Medicine Virology Lab, College of Veterinary Medicine and Research Institute for Veterinary Science, Seoul National University, Seoul, Korea.
Transbound Emerg Dis. 2022 Mar;69(2):538-548. doi: 10.1111/tbed.14017. Epub 2021 Feb 21.
Porcine circovirus 4 (PCV4), a novel and unclassified member of the genus Circovirus, was first reported in China in 2019. Aiming to provide more evidence about the active circulation of PCV4, this study screened 335 pooled internal organs and detected the virus (i) at a rate of 3.28%, (ii) from both clinically healthy and clinically sick pigs of various age groups, and (iii) in six out of nine provinces of Korea. The complete genomic sequence of the Korean PCV4 strain (E115) was 1,770 nucleotides in length and had 98.5%-98.9% identity to three PCV4 strains currently available at GenBank. Utilizing a set of bioinformatic programs, it was revealed that the Korean PCV4 strain contained several genomic features of (i) a palindrome stem-loop structure with a conserved nonanucleotide, (ii) packed overlapping ORFs oriented in different directions and (iii) two intergenic regions in between genes encoding the putative replication-associated protein (Rep) and capsid (Cap) proteins. This study also predicted the presence of essential elements for the replication of circoviruses in all PCV4 strains, for example the origin of DNA replication, endonuclease and helicase domains of Rep, and the nuclear localization signal on the putative Cap protein. Finally, based on the phylogeny inferred from sequences of the putative Rep protein, this study further clarified the genetic relationships between PCV4 and other CRESS DNA viruses in general and circoviruses in particular.
猪圆环病毒4型（PCV4）是圆环病毒属的一个新的未分类成员，于2019年在中国首次报道。为了提供更多关于PCV4活跃传播的证据，本研究对335份合并的内部器官进行了筛查，检测到该病毒：（i）检出率为3.28%；（ii）来自不同年龄组的临床健康猪和临床患病猪；（iii）在韩国九个省份中的六个省份检出。韩国PCV4毒株（E115）的完整基因组序列长度为1770个核苷酸，与GenBank中目前可用的三个PCV4毒株的同源性为98.5%-98.9%。利用一系列生物信息学程序发现，韩国PCV4毒株具有几个基因组特征：（i）具有保守九核苷酸的回文茎环结构；（ii）包装的重叠开放阅读框（ORF）方向不同；（iii）在编码假定的复制相关蛋白（Rep）和衣壳（Cap）蛋白的基因之间有两个基因间隔区。本研究还预测了所有PCV4毒株中圆环病毒复制所需元件的存在，例如DNA复制起点、Rep的核酸内切酶和解旋酶结构域，以及假定的Cap蛋白上的核定位信号。最后，基于从假定的Rep蛋白序列推断的系统发育，本研究进一步阐明了PCV4与其他CRESS DNA病毒特别是圆环病毒之间的遗传关系。
