Department of Animal Science and Technology, Jinling Institute of Technology, Nanjing, China.
PLoS One. 2013 Nov 26;8(11):e81469. doi: 10.1371/journal.pone.0081469. eCollection 2013.
Two species of the DNA virus Torque teno sus virus (TTSuV), TTSuV1 and TTSuV2, have become widely distributed in pig-farming countries in recent years. In this study, we performed a comprehensive analysis of synonymous codon usage bias in 41 available TTSuV2 coding sequences (CDS), and compared the codon usage patterns of TTSuV2 and TTSuV1. TTSuV codon usage patterns were found to be phylogenetically conserved. Values for the effective number of codons (ENC) indicated that the overall extent of codon usage bias in both TTSuV2 and TTSuV1 was not significant, the most frequently occurring codons had an A or C at the third codon position. Correspondence analysis (COA) was performed and TTSuV2 and TTSuV1 sequences were located in different quadrants of the first two major axes. A plot of the ENC revealed that compositional constraint was the major factor determining the codon usage bias for TTSuV2. In addition, hierarchical cluster analysis of 41 TTSuV2 isolates based on relative synonymous codon usage (RSCU) values suggested that there was no association between geographic distribution and codon bias of TTSuV2 sequences. Finally, the comparison of RSCU for TTSuV2, TTSuV1 and the corresponding host sequence indicated that the codon usage pattern of TTSuV2 was similar to that of TTSuV1. However the similarity was low for each virus and its host. These conclusions provide important insight into the synonymous codon usage pattern of TTSuV2, as well as better understangding of the molecular evolution of TTSuV2 genomes.
两种 DNA 病毒——扭结柄病毒(TTSuV)的 TTSuV1 和 TTSuV2 近年来在养猪国家广泛传播。在这项研究中,我们对 41 个可获得的 TTSuV2 编码序列(CDS)进行了同义密码子使用偏好的综合分析,并比较了 TTSuV2 和 TTSuV1 的密码子使用模式。TTSuV 密码子使用模式在系统发育上是保守的。有效密码子数(ENC)的值表明,TTSuV2 和 TTSuV1 的整体密码子使用偏好程度并不显著,最常出现的密码子在第三个密码子位置有一个 A 或 C。进行对应分析(COA)后,TTSuV2 和 TTSuV1 序列位于前两个主坐标轴的不同象限。ENC 的图表明,组成约束是决定 TTSuV2 密码子使用偏好的主要因素。此外,基于相对同义密码子使用(RSCU)值对 41 个 TTSuV2 分离株的层次聚类分析表明,TTSuV2 序列的地理分布与密码子偏倚之间没有关联。最后,对 TTSuV2、TTSuV1 和相应宿主序列的 RSCU 进行比较表明,TTSuV2 的密码子使用模式与 TTSuV1 相似。然而,每个病毒与其宿主之间的相似性都较低。这些结论为 TTSuV2 的同义密码子使用模式提供了重要的见解,并更好地理解了 TTSuV2 基因组的分子进化。