Patterns and mechanisms of hepatitis B/hepatitis D reinfection after liver transplantation.

Viral recurrence is the limiting factor in orthotopic liver transplantation (OLT) for hepatitis B virus (HBV) related liver disease. In fact, high rates of HBV infection of the transplanted liver are reported, followed by the recurrence of liver disease in a high percentage of cases. The importance of reinfection stimulates the study of its modalities and mechanisms in order to better identify preventive measures and better select patients for OLT. In HBV and HDV positive patients, the outcome of liver transplantation appears significantly better than in patients that are solely HBV positive, in spite of a high rate of HDV reinfection. Long-term analysis (5 years) of HBV and HDV infection, using the PCR technique, in 15 patients transplanted for an HBV/HDV positive liver disease and treated with anti-HBs immunoglobulin (HBIG), revealed that all patients experienced an HDV reinfection, but only about 7 were still harboring the virus after four years of follow-up. HDV reinfection was either associated to HBV reinfection or isolated whereas no cases of HBV isolated reinfection was observed. Isolated HDV reinfection was frequent and transient in all but one case that was superinfected by HBV. Infected peripheral blood mononuclear cells seem to be implicated in HBV superinfection of HDV infected liver. Liver damage was observed only in cases of HBV/HDV co-infection, suggesting that, in vivo, HBV is necessary to produce liver damage although it is not essential for HDV absorption to target cells, HDV penetration of these cells or HDV genomic replication. In addition, in isolated HDV infection, transient HDV viraemia and its low levels suggest that, perhaps in these patients HDV uses a very limited presence of HBV or alternative ways which are not efficient enough for envelope production. These data suggest that, particularly in HDV positive patients, antiHBs Ig administration, which has previously been proven to significantly reduce HBV reinfection in HBsAg-positive patients, may be useful in changing the natural history of repetition of the original viral infection and liver disease after OLT.