Prevalence and clinical significance of occult hepatitis B virus infection among renal transplant recipients in Korea

Background : Occult hepatitis B infection (OBI) is the presence of hepatitis B virus (HBV) DNA in serum or hepatic tissue without detectable hepatitis B surface antigen (HBsAg) in serum. Kidney disease patients in the post-renal transplantation period are in a specific situation as a result of the high pre-transplantational risk of HBV infection and post-transplantational immunosuppression. We studied the pre-transplantational prevalence and post-transplantational influence of OBI on kidney transplantation patients. Methods : We investigated pre-transplantational serum samples of 217 HBsAg-negative patients of post-renal transplant status for the presence of HBV DNA by real-time quantitative polymerase chain reaction. Serologic markers for HBV and hepatitis C virus (HCV) infection as well as liver enzymes were analyzed. Results : We detected HBV DNA in 2.3% (5/217) of HBsAg-negative patients, and the median HBV DNA titer was 33.15 copies/ml (range 30.6-144.6 copies/ml). Among the 5 OBI patients, 2 had hepatitis B surface antibodies (anti-HBs) and 1 had hepatitis B core antibodies (anti-HBc IgG). None of the patients with OBI were co-infected with HCV. There was no evidence of reactivation of OBI during the 36-month (range 27-63 months) follow-up monitoring period after transplantation, in spite of immune suppression to prevent rejection. Conclusions: The prevalence of occult HBV in the setting of renal transplantation was higher than that in the general population of Korea, and no reactivation of hepatitis B was observed in patients with OBI in the post-renal transplantation period.