title: Comments on duck circovirus (DuCV) genotype definition.
abstract: A standardised methodology has been used to define genotypes based on pairwise sequence comparisons (PASC). PASC is a widely accepted method in virus taxonomy, which is based on the histogram of pairwised differences among sequences. Recently, Zhang et al. (2013) concluded that the average p-distance of duck circovirus (DuCV) between genotypes 1 and 2 was 0.170, and subtype distance thresholds were 0.032 in DuCV-1 and 0.018 in DuCV-2, respectively. However, there might be some concerns on the methodology application to define the genotype of DuCV. Taking into account the concerns mentioned above, our authors conducted the PASC analyses of 54 capsid gene (ORF2) and genomic sequences including all the sequences from Zhang et al. (2013). Our results confirmed the existence of two DuCV genotypes (1 and 2) and, we suggest that DuCV ORF2 and genomic distance genotype thresholds were 0.061 and 0.038, respectively.
authors.affiliation: Laboratory Animal and Comparative Medicine Unit, State Key Laboratory of Veterinary Biotechnology, Harbin Veterinary Research Institute, Chinese Academy of Agricultural Sciences, Harbin 150001, People's Republic of China. Electronic address: wen_huiqiang@163.com.
authors.forename: Huiqiang
authors.initials: H
authors.lastname: Wen
authors.affiliation: Laboratory Animal and Comparative Medicine Unit, State Key Laboratory of Veterinary Biotechnology, Harbin Veterinary Research Institute, Chinese Academy of Agricultural Sciences, Harbin 150001, People's Republic of China. Electronic address: wysh0224@gmail.com.
authors.forename: Yongshu
authors.initials: Y
authors.lastname: Wu
authors.affiliation: Laboratory Animal and Comparative Medicine Unit, State Key Laboratory of Veterinary Biotechnology, Harbin Veterinary Research Institute, Chinese Academy of Agricultural Sciences, Harbin 150001, People's Republic of China. Electronic address: ych20071271@foxmail.com.
authors.forename: Chao
authors.initials: C
authors.lastname: Yang
authors.affiliation: Laboratory Animal and Comparative Medicine Unit, State Key Laboratory of Veterinary Biotechnology, Harbin Veterinary Research Institute, Chinese Academy of Agricultural Sciences, Harbin 150001, People's Republic of China. Electronic address: hailanzhixin.hi@163.com.
authors.forename: Xiaona
authors.initials: X
authors.lastname: Zhang
authors.affiliation: Laboratory Animal and Comparative Medicine Unit, State Key Laboratory of Veterinary Biotechnology, Harbin Veterinary Research Institute, Chinese Academy of Agricultural Sciences, Harbin 150001, People's Republic of China. Electronic address: lcj121916@163.com.
authors.forename: Chuanjiang
authors.initials: C
authors.lastname: Lian
authors.affiliation: Laboratory Animal and Comparative Medicine Unit, State Key Laboratory of Veterinary Biotechnology, Harbin Veterinary Research Institute, Chinese Academy of Agricultural Sciences, Harbin 150001, People's Republic of China. Electronic address: hychen@hvri.ac.cn.
authors.forename: Hongyan
authors.initials: H
authors.lastname: Chen
authors.affiliation: Laboratory Animal and Comparative Medicine Unit, State Key Laboratory of Veterinary Biotechnology, Harbin Veterinary Research Institute, Chinese Academy of Agricultural Sciences, Harbin 150001, People's Republic of China. Electronic address: hlx1993@126.com.
authors.forename: Lingxia
authors.initials: L
authors.lastname: Han
mesh_terms: D000818:Animals; D017925:Circovirus / Q000235:genetics*; D004279:DNA, Viral / Q000737:chemistry / Q000235:genetics; D004372:Ducks / Q000821:virology; D005838:Genotype; D016415:Sequence Alignment / Q000379:methods*
chemical_list: D004279:DNA, Viral
keywords: Duck circovirus; Genotype; Pairwise sequence comparisons (PASC)