Transfusion transmitted virus infection in general populations and patients with various liver diseases in south China

Although several specific detecting methods had been applied to determine the hepatitis virus, there was a lot of cryptogenic hepatitis without any known hepatitis infectious marker[1]. The prevalence of hepatitis G virus (HGV) (also known as GB-C virus) infection has been reported to be 5%-13% in patients with non-A-E hepatitis and cirrhosis, however, there is little evidence suggesting that HGV causes hepatitis in human[2-6]. Although cryptogenic liver diseases are almost certainly related to a variety of etiologies, one or more as-yet-unidentified infectious agents are likely to account for a proportion of these cases. In December 1997, a novel DNA virus was reported by Nishizawa et al[7] to be associated with elevated aminotransferase levels in patients with post-transfusion hepatitis of unknown etiology (non-A-G hepatitis). This virus was designated transfusion transmitted virus (TTV). Then, Luo et al[8] and Wei et al[9] also detected TTV in the sera of patients from an outbreak of cryptogenic hepatitis in south China. And TTV was also detected in patients with post-transfusion hepatitis in China[10]. In subsequent analyses, TTV is an un-enveloped single-stranded DNA virus for which a sequence of 3800 bases was determined[11]. Evidence of potential hepatotropism of TTV was reported with TTV DNA detected in liver tissue[12]. Histopathological study indicated that the characteristics of liver histology of TTV infected patients are portal inflammation and interlobular bile duct damage[13]. TTV was proposed as the part of causative agent of non-A to G hepatitis. Seroepidemiological studies have shown TTV to have global distribution[12,14,15]. Although the potential association of TTV with cryptogenic hepatitis is intriguing, the pathological and clinical significance of this virus remains to be established. To assess more thoroughly the etiological role of TTV in the causation of hepatitis, we determined the frequency of TTV infections and their relationship to liver disease in several cohorts of liver diseases and rural population.