title: Molecular epidemiology and clinical implications of TT virus (TTV) infection in Indian subjects.
abstract: OBJECTIVE
  This study was aimed at obtaining data on the epidemiology and clinical course of TT virus (TTV) infections among Indian subjects.
  
  
  BACKGROUND
  The TTV is a nonenveloped DNA virus, first identified in the peripheral blood of individuals with posttransfusion hepatitis of unknown etiology. There has been much conjecture regarding the disease association of this virus.
  
  
  METHODS
  A total of 494 serum specimens from various groups of high-risk and control subjects were screened for TTV DNA by a semi-nested PCR, using the ORF1-derived N22 primers. The sera were also screened for the HBsAg surface antigen by an ELISA, HCV RNA by a 5' NCR-based RT-PCR and GBV-C/HGV RNA by a 5' UTR-based RT-PCR. The clinical and hepatic profiles of the various subjects were also studied. Seventy-one randomly picked TTV isolates were directly sequenced and their phylogeny was studied.
  
  
  RESULTS
  TTV showed an overall positivity rate of 45.34% with a significant higher prevalence of 52.9% among the high-risk subjects as against a prevalence of 28% among healthy control subjects (P < 0.001). Abnormal liver function profiles were frequent among TTV viremic individuals and among the acute hepatitis cases studied a higher mortality rate correlated with a superimposed TTV infection. The 71 TTV isolates sequenced were found to belong to genotype 1a being closely homologous to TTV prototype TA278.
  
  
  CONCLUSIONS
  The TT virus shows a significant prevalence in the Indian population, particularly among subjects at risk for acquiring parenterally transmitted infections. Our study corroborates a putative role of the virus in the etiology of liver disease, particularly in coinfection with other agents.
authors.affiliation: Department of Microbiology, Sir Hurkisondas Nurrotumdas Medical Research Society, Sir H. N. Hospital and Research Centre, Mumbai, India.
authors.forename: Mayura M
authors.initials: MM
authors.lastname: Desai
authors.forename: Ramprasad B
authors.initials: RB
authors.lastname: Pal
authors.forename: Dushyant D
authors.initials: DD
authors.lastname: Banker
mesh_terms: D000293:Adolescent; D000328:Adult; D017677:Age Distribution; D000368:Aged; D000369:Aged, 80 and over; D000914:Antibodies, Viral / Q000276:immunology*; D002648:Child; D002675:Child, Preschool; D018173:Circoviridae Infections / Q000097:blood / Q000453:epidemiology* / Q000821:virology; D004279:DNA, Viral / Q000235:genetics*; D004797:Enzyme-Linked Immunosorbent Assay; D005260:Female; D006801:Humans; D015994:Incidence; D007194:India / Q000453:epidemiology; D007223:Infant; D008297:Male; D008875:Middle Aged; D017720:Molecular Epidemiology / Q000379:methods; D012189:Retrospective Studies; D020133:Reverse Transcriptase Polymerase Chain Reaction; D017678:Sex Distribution; D015996:Survival Rate; D022783:Torque teno virus / Q000235:genetics / Q000276:immunology / Q000302:isolation & purification
chemical_list: D000914:Antibodies, Viral; D004279:DNA, Viral