Effect of selective vaccination on a decrease in the rate of hepatitis B virus-positive Japanese first-time blood donors.

The government of Japan started a selective vaccination programme to prevent mother-to-infant infection by hepatitis B virus (HBV) since January 1986. The effect of the programme on first-time blood donors has not been examined in detail. Data of first-time blood donors aged 16-25 years from 1996 to 2007 were extracted from the Japanese Red Cross (JRC) donors' database. Principal component analysis (PCA) was used to visualize the birth-year-dependent group of rate of HBV-positive donors. According to the birth of year, donors were divided into four groups by PCA. After the start of the programme, donors born in 1986-1989 comprised a single group. Before the start of the programme, three groups (1980, 1981-1984 and 1985) were identified. Although a significant time-dependent decrease in the rate of HBV-positive donors was observed before the start of the programme, a significant difference in the rate of HBV-positive donors was observed around the start of the programme by regression analysis for 16-19-year-old first-time blood donors. The selective vaccination programme has been effective to prevent the vertical transmission of HBV from the analysis of first-time blood donors. On the other hand, vaccination of blood donors should be considered to reduce the risk of post-transfusion HBV infection, because the horizontal transmission increases in HBV-positive blood donors.

A new method of concentrating hepatitis B virus (HBV) DNA and HBV surface antigen: an application of the method to the detection of occult HBV infection.

BACKGROUND: The risk of post-transfusion hepatitis B virus (HBV) infection has been reduced after the implementation of HBV nucleic acid amplification technology (NAT). However, the problem of HBV DNA-positive and HBV surface antigen (HBsAg)-negative occult HBV infections remains to be solved. This is in part due to the HBV DNA load being too low to detect these occult HBV infections using mini-pool NAT. In Japan, the assay for the antibody against the HBV core antigen (anti-HBc) has not completely excluded occult HBV infection. To solve this problem, we have developed a new method of concentrating HBV DNA and HBsAg simultaneously to increase the sensitivity of detection tests. METHODS: Virus concentration is achieved by the enhancement of the agglutination of viruses using poly-L-lysine in the presence of a bivalent metal. Poly-L-lysine-coated magnetic beads are used to shorten the time of each step of the concentration procedure. Seventy-seven anti-HBc-positive and HBsAg-negative donations were examined. HBsAg and anti-HBc were tested by enzyme immunoassay (EIA) (AxSYM; Abbott) and haemagglutination inhibition test (Japanese Red Cross), respectively. RESULTS: HBV surface antigen and HBV DNA levels were concentrated up to four- to sevenfold. Using this method, 35 of the 77 anti-HBc-positive and HBsAg-negative donors were HBV DNA-positive by individual NAT and a further five donors became HBV DNA-positive by HBV concentration. Twenty-seven of 40 occult HBV infections became HBsAg-positive by HBsAg concentration. CONCLUSION: Our new method of concentrating HBV and HBsAg increased the sensitivities of EIA and HBV NAT, and enabled us to detect 27 of 40 occult HBV infections by HBsAg EIA.