1. HBV screening Further improvement of blood safety based on the knowledge deduced from the results on analysis of the donor’s sera positive for HBV DNA by NAT as well as the results of experimental HBV infection to Chimpanzees HiroshiYOSHIZAWA 1 MD JunkoTANAKA 1 PhD KeikoKATAYAMA 1 MD HisaoYUGI 2 PhD TetsushiTOMOGURI 3 PhD 1.Graduate School of Biomedical Sciences, Hiroshima University, Hiroshima, Japan 2.Division of NAT, Japanese Red Cross Association, Tokyo, Japan 3.Primate Center, Sanwa Kagak, Ltd., Kumamoto, Japan

2. ● Importance of HBV DNA Testing ● Natural Course of Persistent HBV infection - typical/ or classical pattern of HBV carrier state - ● Natural Course of Acute HBV Infection clinically: anamnestic infection virologically : (atypical) HBV carrier state ● Characteristics of Acute HBV Infection Late phase of Infection ● Relationship between quantity of HBV DNA and titer of anti HBc

3. ● Detection of HBsAg by highly sensitive immunoassay method (PRISM) in 268 early phase of HBV infected blood donors : both negative for HBsAg (by R-PHA method) and anti HBc ( by CLIA method) ● Experimental HBV infection using model animal (Chimpanzees) ● Results of the experiment - 10 copies of HBV DNA can transmit HBV to Chimpanzees - ● Doubling time and log time of HBV DNA in the peripheral blood of HBV (genotype A, early phase) infected Chimpanzees ● Characteristics of Acute HBV Infection Early phase of Infection

4. Importance of HBV DNA testing for Blood Safety For late stage of HBV infection Strategy should be different in hyper-endemic area and low- endemic area of HBV infection. For early stage of HBV infection Generally saying, it is almost impossible to achieve 100% of blood safety by HBV DNA testing solely both in hyper-endemic area and low-endemic area. Other strategy such as social edecation to donors should be considered. conclusion