The Roslin Institute and The Royal (Dick) School of Veterinary Studies, University of Edinburgh, Midlothian, UK; Department of Veterinary Diagnostic and Production Animal Medicine, College of Veterinary Medicine, Iowa State University, Ames, Iowa, USA.
Vaccine Research Centre-Viral Vaccines, Centre for Animal Health Studies, Tamil Nadu Veterinary and Animal Sciences University, Chennai, India.
Virus Res. 2020 Sep;286:198044. doi: 10.1016/j.virusres.2020.198044. Epub 2020 Jun 2.
Circoviruses (CV) include some of the smallest viruses known. They were named after their circularly arranged single-stranded DNA genome with a gene encoding a conserved replicase protein on the sense strand. Circoviruses are widely distributed in mammals, fish, avian species and even insects. In pigs, four different CVs have been identified and named with consecutive numbers based on the order of their discovery: Porcine circovirus 1 (PCV1), Porcine circovirus 2 (PCV2), Porcine circovirus 3 (PCV3) and most recently Porcine circovirus 4 (PCV4). PCVs are ubiquitous in global pig populations and uninfected herds are rarely found. It is generally accepted that PCV1 is non-pathogenic. In contrast, PCV2 is considered an important, economically challenging pathogen on a global scale with comprehensive vaccination schemes in place. The role of PCV3 is still controversial several years after its discovery. Propagation of PCV3 appears to be challenging and only one successful experimental infection model has been published to date. Similarly to PCV2, PCV3 is widespread and found in many pigs regardless of their health history, including high health herds. PCV4 has only recently been discovered and further information on this virus is required to understand its potential impact. This review summarizes current knowledge on CVs in pigs and aims to contrast and compare known facts on PCVs.
圆环病毒（Circoviruses，CV）属于最小的病毒之一。它们以其圆形排列的单链 DNA 基因组命名，该基因组在正义链上具有编码保守复制酶蛋白的基因。圆环病毒广泛分布于哺乳动物、鱼类、禽类，甚至昆虫中。在猪中，已经鉴定出四种不同的 CV，并根据发现顺序连续编号：猪圆环病毒 1（Porcine circovirus 1，PCV1）、猪圆环病毒 2（Porcine circovirus 2，PCV2）、猪圆环病毒 3（Porcine circovirus 3，PCV3）和最近发现的猪圆环病毒 4（Porcine circovirus 4，PCV4）。PCVs 在全球猪群中普遍存在，很少发现未感染的猪群。通常认为 PCV1 是无致病性的。相比之下，PCV2 被认为是一种具有重要意义的、在全球范围内具有经济挑战性的病原体，目前已制定了全面的疫苗接种计划。PCV3 的作用在其发现几年后仍存在争议。PCV3 的繁殖似乎具有挑战性，迄今为止仅发表了一个成功的实验感染模型。与 PCV2 类似，PCV3 广泛存在于许多猪中，无论其健康史如何，包括高健康猪群。PCV4 最近才被发现，需要更多关于该病毒的信息来了解其潜在影响。这篇综述总结了目前关于猪圆环病毒的知识，并旨在对比和比较已知的 PCV 事实。
