Franzo Giovanni, Cortey Martí, Olvera Alex, Novosel Dinko, Castro Alessandra Marnie Martins Gomes De, Biagini Philippe, Segalés Joaquim, Drigo Michele
Department of Animal Medicine, Production and Health (MAPS), University of Padua, Viale dell'Università 16, Legnaro, PD, 35020, Italy.
The Pirbright Institute, Pirbright, Woking, UK.
Virol J. 2015 Aug 28;12:131. doi: 10.1186/s12985-015-0361-x.
PCV2 has emerged as one of the most devastating viral infections of swine farming, causing a relevant economic impact due to direct losses and control strategies expenses. Epidemiological and experimental studies have evidenced that genetic diversity is potentially affecting the virulence of PVC2. The growing number of PCV2 complete genomes and partial sequences available at GenBank questioned the accepted PCV2 classification.
Nine hundred seventy five PCV2 complete genomes and 1,270 ORF2 sequences available from GenBank were subjected to recombination, PASC and phylogenetic analyses and results were used for comparison with previous classification scheme.
The outcome of these analyses favors the recognition of four genotypes on the basis of ORF2 sequences, namely PCV2a, PCV2b, PCV2c and PCV2d-mPCV2b. To deal with the difficulty of founding an unambiguous classification and accounting the impossibility to define a p-distance cut-off, a set of reference sequences that could be used in further phylogenetic studies for PCV2 genotyping was established. Being aware that extensive phylogenetic analyses are time-consuming and often impracticable during routine diagnostic activity, ORF2 nucleotide positions adequately conserved in the reference sequences were identified and reported to allow a quick genotype differentiation.
Globally, the present work provides an updated scenario of PCV2 genotypes distribution and, based on the limits of the previous classification criteria, proposes new rapid and effective schemes for differentiating the four defined PCV2 genotypes.
猪圆环病毒2型（PCV2）已成为养猪业中最具破坏性的病毒感染之一，因其直接损失和防控策略费用而造成重大经济影响。流行病学和实验研究表明，基因多样性可能影响PCV2的毒力。GenBank上可获得的PCV2完整基因组和部分序列数量不断增加，这对已被认可的PCV2分类提出了质疑。
对GenBank中可获得的975个PCV2完整基因组和1270个ORF2序列进行重组、PASC和系统发育分析，并将结果用于与先前的分类方案进行比较。
这些分析结果支持基于ORF2序列识别四种基因型，即PCV2a、PCV2b、PCV2c和PCV2d-mPCV2b。为了解决建立明确分类的困难以及考虑到无法定义一个明确的分类，建立了一组可用于PCV2基因分型的进一步系统发育研究的参考序列。由于意识到在常规诊断活动中进行广泛的系统发育分析既耗时又往往不切实际，因此确定并报告了参考序列中充分保守的ORF2核苷酸位置，以便快速进行基因型区分。
在全球范围内，本研究提供了PCV2基因型分布的最新情况，并基于先前分类标准的局限性，提出了区分四种已定义的PCV2基因型的新的快速有效方案。
