Poovorawan Y, Tangkijvanich P, Theamboonlers A, Hirsch P
Viral Hepatitis Research Unit, Department of Paediatrics, Faculty of Medicine, Chulalongkorn University & Hospital, Bangkok 10330, Thailand.
Hepatogastroenterology. 2001 Jan-Feb;48(37):256-60.
TTV, the transfusion transmissible hepatitis virus infects mainly patients at risk for parenteral exposure and hence, prone to develop chronic liver disease, as well as healthy populations worldwide. Most TTV infections appear to occur parenterally, with viremia detected frequently in blood donors and blood products. The substantial proportion of asymptomatic individuals never exposed to blood-borne agents, and its high prevalence among healthy subjects implicates the fecal-oral route as another potential for transmission. According to the TTV DNA levels detected in liver tissue, it apparently replicates in hepatocytes, and TTV DNA is present in sera of patients with posttransfusion hepatitis of unknown etiology closely correlated with ALT levels. However, TTV initiating the development of chronic liver disease or causing posttransfusion hepatitis could not be confirmed, as most patients positive for TTV DNA remain asymptomatic and those progressing towards chronic liver disease are invariably coinfected with either the hepatitis B or C virus. Also, TTV coinfection does not aggravate the symptoms associated with hepatitis B or C. Similarly, it does not cause posthepatitis aplastic anemia, and high-risk patients can immunologically clear the viral DNA. In conclusion, being widely distributed and apparently nonpathogenic, TTV might represent an opportunistic but innocent virus reminiscent of hepatitis G virus, with a negligible role in the etiology of chronic liver disease.
输血传播性肝炎病毒（TTV）主要感染有肠道外暴露风险的患者，因此容易发展为慢性肝病，在全球健康人群中也有感染情况。大多数TTV感染似乎通过肠道外途径发生，在献血者和血液制品中经常检测到病毒血症。相当一部分从未接触过血源性病原体的无症状个体，以及其在健康受试者中的高流行率表明粪-口途径是另一种潜在传播途径。根据在肝组织中检测到的TTV DNA水平，它显然在肝细胞中复制，并且在病因不明的输血后肝炎患者的血清中存在TTV DNA，其与ALT水平密切相关。然而，TTV引发慢性肝病的发展或导致输血后肝炎尚未得到证实，因为大多数TTV DNA阳性患者仍无症状，而那些进展为慢性肝病的患者总是同时感染乙型或丙型肝炎病毒。此外，TTV合并感染不会加重与乙型或丙型肝炎相关的症状。同样，它不会导致肝炎后再生障碍性贫血，高危患者可以通过免疫清除病毒DNA。总之，TTV分布广泛且显然无致病性，可能是一种机会性但无害的病毒，类似于庚型肝炎病毒，在慢性肝病的病因学中作用微不足道。
