Genotypes of TT virus (TTV) compared between liver disease patients and healthy individuals using a new PCR system capable of differentiating 1a and 1b types from others*.
TT virus (TTV) lacks obvious pathogenicity; almost all of the infected hosts are symptom-free. A possibility remains, however, that certain strains can cause liver disease while most others are non-pathogenic. Genotypes 1 a and 1 b have been proposed to contain such pathogenic strains. To test this possibility, we constructed a PCR system capable of detecting TTV of the 1 a and 1 b genotypes differentially from the other genotypes, and compared the frequencies of these genotypes between patients with liver disease of unknown etiology (n=42) and healthy individuals (n=50). The assay comprised 3 steps: i) PCR to amplify a 3.2-kb fragment using universal primers; ii) 2nd-round PCR, starting from the 3.2-kb amplicon, for a approximately 280-nt fragment by use of genotype 1-specific primers; and iii) digestion of the approximately 280-nt amplicon with MboI and BanI to discriminate between 1 a and 1 b. Eventually, 40 (95%) of the patients and 47 (94%) of the controls were positive for the 3.2-kb amplicon, and the 1 a, 1 b, 1 a+1 b, and non-1 genotypes of TTV were found in 2 (5%) vs 4 (9 percent), 5 (13%) vs 4 (9%), 1 (3%) vs 1 (2%) and 32 (80%) vs 38 (81%) of the 40 patients and 47 controls, respectively: the distribution was almost identical between the two groups. The hypothesis that the genotype 1 of TTV may be more closely associated with liver disease than other genotypes was not supported by this study.
Hijikata
M
M
Department of Medical Sciences, Toshiba General Hospital, Tokyo, Japan.
Iwata
K
K
Ohta
Y
Y
Nakao
K
K
Matsumoto
M
M
Matsumoto
H
H
Kanai
K
K
Baba
K
K
Samokhvalov
E I
EI
Mishiro
S
S
D001483:Base Sequence; D016022:Case-Control Studies; D017931:DNA Primers; D004266:DNA Virus Infections / Q000821:virology*; D004267:DNA Viruses / Q000145:classification / Q000235:genetics* / Q000472:pathogenicity*; D004279:DNA, Viral / Q000302:isolation & purification; D005838:Genotype; D006525:Hepatitis, Viral, Human / Q000821:virology*; D006801:Humans; D008107:Liver Diseases / Q000821:virology*; D008969:Molecular Sequence Data; D016133:Polymerase Chain Reaction / Q000379:methods; D017422:Sequence Analysis, DNA
D017931:DNA Primers; D004279:DNA, Viral