Molecular epidemiology and clinical implications of TT virus (TTV) infection in Indian subjects.
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.
Desai
Mayura M
MM
Department of Microbiology, Sir Hurkisondas Nurrotumdas Medical Research Society, Sir H. N. Hospital and Research Centre, Mumbai, India.
Pal
Ramprasad B
RB
Banker
Dushyant D
DD
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
D000914:Antibodies, Viral; D004279:DNA, Viral