Department of Microbiology and Immunology, Faculty of Veterinary Medicine, Kasetsart University, Thailand.
Virol J. 2011 Feb 28;8:88. doi: 10.1186/1743-422X-8-88.
Porcine circovirus type 2 (PCV2) is the major swine pathogen associated with Porcine circovirus associated disease (PCVAD) including post-weaning multisystemic wasting syndrome (PMWS). Currently, there are 4 subtypes of PCV2 (PCV2a, b, c and d) and some epidemiological evidences demonstrated that virulence of PCV2 may relate to its subtypes. Recently, PMWS was observed more frequently in swine farms in Thailand; however, the information regarding to PCV2 subtype involved was limited. Therefore, this study was aimed to determine the association between occurrence of PMWS and PCV2 subtypes as well as genetically characterize PCV2 in Thailand. PCV2 DNA was isolated from faecal swabs and whole blood of piglets from PMWS-affected and -negative farms. The full length ORF2 sequences were compared using multiple alignment. The results showed that PCV2 DNA was detected more frequently in PMWS-affected farms. The nucleotide identities of the ORF2 from 9 PCV2 isolates representing each PMWS-affected farm and one from the negative farm ranged from 92.4 to 99.5% suggesting that there is some genetic variation of PCV2 in Thai swine. The 10 PCV2 isolates were classified into 2 clusters, in which the 7 isolates from PMWS-positive farms were in PCV2b cluster 1 A/B. The remaining isolates were separated in the new subtype called PCV2e. The results suggest the presence of new PCV2 subtypes in addition to PCV2a and PCV2b in Asian swine population. However, correlation between subtypes and virulence of PCV2 infection is not conclusive due to limited number of the PCV2 sequences from PMWS negative farms.
猪圆环病毒 2 型（PCV2）是与猪圆环病毒相关疾病（PCVAD）相关的主要猪病原体，包括断奶后多系统消耗综合征（PMWS）。目前，PCV2 有 4 个亚型（PCV2a、b、c 和 d），一些流行病学证据表明，PCV2 的毒力可能与其亚型有关。最近，泰国的猪场中更频繁地观察到 PMWS；然而，涉及的 PCV2 亚型的信息有限。因此，本研究旨在确定 PMWS 的发生与 PCV2 亚型之间的关系，并对泰国的 PCV2 进行遗传特征分析。从 PMWS 阳性和阴性农场的仔猪粪便拭子和全血中分离 PCV2 DNA。使用多重比对比较 ORF2 全长序列。结果表明，PCV2 DNA 在 PMWS 阳性农场中检测更为频繁。来自 9 个 PMWS 阳性农场的每一个代表农场的 PCV2 分离株和一个阴性农场的 ORF2 核苷酸同一性为 92.4%至 99.5%，表明泰国猪群中存在一些 PCV2 的遗传变异。这 10 个 PCV2 分离株分为 2 个簇，其中来自 PMWS 阳性农场的 7 个分离株属于 PCV2b 簇 1A/B。其余的分离株则属于新的称为 PCV2e 的亚型。结果表明，除了 PCV2a 和 PCV2b 之外，亚洲猪群中还存在新的 PCV2 亚型。然而，由于 PMWS 阴性农场的 PCV2 序列数量有限，因此，PCV2 亚型与感染毒力之间的相关性尚不确定。
