GB virus C and TT virus infections in Japanese patients with autoimmune hepatitis

The association of the newly identified viruses, GB virus C (GBV-C) and TT virus (TTV), with autoimmune hepatitis remains to be elucidated. Sera from 20 Japanese patients with autoimmune hepatitis and 50 volunteer blood donors were assayed for GBV-C RNA, antibodies to the GBV-C second envelope protein (E2), and TTV DNA. GBV-C RNA was examined by reverse-transcription polymerase chain reaction (PCR). Anti-GBV-C E2 (a marker of past infection) was tested by an enzyme-linked immunosorbent assay. TTV DNA was amplified by PCR using two different sets of primers: one derived from the original N22 sequence (Set A) and the other from the untranslated region (Set B). None of the patients or controls had GBV-C RNA. Anti-GBV-C E2 was found significantly more often in patients with autoimmune hepatitis (3/20) than in controls (1/50; P = 0.034). The prevalence of TTV DNA detected by primers Set A and that detected with either Set A or B were similar among patients with autoimmune hepatitis (4/20 and 16/20, respectively) and controls (9/50 and 40/50, respectively). Clinical characteristics did not differ in association with any of these viral markers. Of the 13 TTV isolates amplified with Set A, seven were classified as genotype 1a, four as genotype 1b, and 2 as genotype 3; no particular strain was associated with autoimmune hepatitis. These findings provide no compelling evidence that GBV-C or TTV has a pathogenic role in autoimmune hepatitis.