title: Coevolution between simple sequence repeats (SSRs) and virus genome size.
abstract: BACKGROUND
  Relationship between the level of repetitiveness in genomic sequence and genome size has been investigated by making use of complete prokaryotic and eukaryotic genomes, but relevant studies have been rarely made in virus genomes.
  
  
  RESULTS
  In this study, a total of 257 viruses were examined, which cover 90% of genera. The results showed that simple sequence repeats (SSRs) is strongly, positively and significantly correlated with genome size. Certain repeat class is distributed in a certain range of genome sequence length. Mono-, di- and tri- repeats are widely distributed in all virus genomes, tetra- SSRs as a common component consist in genomes which more than 100 kb in size; in the range of genome < 100 kb, genomes containing penta- and hexa- SSRs are not more than 50%. Principal components analysis (PCA) indicated that dinucleotide repeat affects the differences of SSRs most strongly among virus genomes. Results showed that SSRs tend to accumulate in larger virus genomes; and the longer genome sequence, the longer repeat units.
  
  
  CONCLUSIONS
  We conducted this research standing on the height of the whole virus. We concluded that genome size is an important factor in affecting the occurrence of SSRs; hosts are also responsible for the variances of SSRs content to a certain degree.
authors.affiliation: Chinese Academy of Inspection and Quarantine, Beijing, 100029, China.
authors.forename: Xiangyan
authors.initials: X
authors.lastname: Zhao
authors.forename: Yonglei
authors.initials: Y
authors.lastname: Tian
authors.forename: Ronghua
authors.initials: R
authors.lastname: Yang
authors.forename: Haiping
authors.initials: H
authors.lastname: Feng
authors.forename: Qingjian
authors.initials: Q
authors.lastname: Ouyang
authors.forename: You
authors.initials: Y
authors.lastname: Tian
authors.forename: Zhongyang
authors.initials: Z
authors.lastname: Tan
authors.forename: Mingfu
authors.initials: M
authors.lastname: Li
authors.forename: Yile
authors.initials: Y
authors.lastname: Niu
authors.forename: Jianhui
authors.initials: J
authors.lastname: Jiang
authors.forename: Guoli
authors.initials: G
authors.lastname: Shen
authors.forename: Ruqin
authors.initials: R
authors.lastname: Yu
mesh_terms: D001483:Base Sequence; D019143:Evolution, Molecular; D059646:Genome Size; D016679:Genome, Viral; D018895:Microsatellite Repeats / Q000235:genetics*; D025341:Principal Component Analysis; D014780:Viruses / Q000235:genetics*