Infection by an unenveloped DNA virus associated with non-A to -G hepatitis in Japanese blood donors with or without elevated ALT levels

BACKGROUND: An unenveloped, single-stranded DNA virus named TT virus has be en found in association with elevated alanine aminotransferase (ALT) levels in recipients of transfusions and has been detected frequently in patients with acute or chronic hepatitis of non-A to -G etiology in Japan. DNA of t he TT virus was searched for in blood donors with or without elevated ALT l evels. STUDY DESIGN AND METHODS: A total of 861 blood donors without previous tran sfusions and who were negative for markers of hepatitis B or C virus infect ion were tested. DNA of the TT virus was detected by polymerize chain react ion with hemi-nested primers. RESULTS: TT virus DNA was detected in 62 of 280 (22.1% [95% CI: 18.1-26.6]) donors with elevated ALT levels (mean +/- SD, 89.3 +/- 36.4 U/L; range, 61 -301 U/L), which is significantly more frequently (p<0.02) than its detecti on in 91 of 581 (15.7% [95% CI: 13.2-18.4]) donors with normal ALT (less th an or equal to 45 U/L). The frequency of TT virus DNA increased with age, i n donors with and without elevated ALT. CONCLUSION: The detection of TT virus DNA, at a frequency higher in donors with elevated ALT than in those without, strengthens the association of TT virus with non-A to -G hepatitis.