title: Three new emerging subgroups of Torque teno sus viruses (TTSuVs) and co-infection of TTSuVs with porcine circovirus type 2 in China.
abstract: BACKGROUND
  Torque teno sus viruses (TTSuVs) are non-enveloped viruses and have single-stranded, negative sense circular DNA genomes and are widely distributed in pigs. But till now, the prevalence of TTSuVs with porcine circovirus type 2 (PCV2) in pig herds of China is not very clear; and the genetic variation among different TTSuVs isolate is very large and need to divide the subgroups. In this study, the co-infection with TTSuVs and porcine circovrius (PCV) in the pig population of China was investigated and the subgroups of all TTSuVs genomes in Genbank were divided.
  
  
  RESULTS
  Results showed that the rate of co-infection with TTSuV1 and TTSuV2 reached 75% in PCV2-positive samples. Also Two TTSuV1 and four TTSuV2 isolates genome sequences were obtained, and the similarity of all TTSuV1 and TTSuV2 genomic sequences in GenBank were compared. Phylogenetic trees indicated that both the TTSuV1 and TTSuV2 sequences could be divided into four genotypes. Interestingly, the sub-genotypes TTSuV1d, TTSuV2c and TTSuV2d exist only in the pig population of China.
  
  
  CONCLUSIONS
  This study demonstrates that co-infection with TTSuVs and PCVs is very common in the pig population of China, in which the viruses maybe contribute to clinical diseases cooperatively. In addition, three new subgroups of TTSuVs emerged in China for the first time and a high level of variation among different isolates of TTSuV1 and TTSuV2 was indicated by their genetic diversity.
authors.affiliation: Division of Swine Infectious Diseases, State Key Laboratory of Veterinary Biotechnology, Harbin Veterinary Research Institute, The Chinese Academy of Agricultural Sciences, 427 Maduan Street, Nangang District, Harbin 150001, China.
authors.forename: Jianbo
authors.initials: J
authors.lastname: Liu
authors.forename: Longjun
authors.initials: L
authors.lastname: Guo
authors.forename: Long
authors.initials: L
authors.lastname: Zhang
authors.forename: Yanwu
authors.initials: Y
authors.lastname: Wei
authors.forename: Liping
authors.initials: L
authors.lastname: Huang
authors.forename: Hongli
authors.initials: H
authors.lastname: Wu
authors.forename: Changming
authors.initials: C
authors.lastname: Liu
mesh_terms: D000818:Animals; D002681:China; D017925:Circovirus / Q000302:isolation & purification*; D016000:Cluster Analysis; D060085:Coinfection / Q000453:epidemiology / Q000662:veterinary* / Q000821:virology; D004266:DNA Virus Infections / Q000453:epidemiology / Q000662:veterinary* / Q000821:virology; D004279:DNA, Viral / Q000737:chemistry / Q000235:genetics; D005838:Genotype; D008969:Molecular Sequence Data; D010802:Phylogeny; D015995:Prevalence; D017422:Sequence Analysis, DNA; D013552:Swine; D013553:Swine Diseases / Q000453:epidemiology* / Q000821:virology*; D022783:Torque teno virus / Q000145:classification* / Q000235:genetics / Q000302:isolation & purification*
chemical_list: D004279:DNA, Viral