Timothy M Block1, Ju-Tao Guo2. 1. Hepatitis B Foundation, Doylestown, Pennsylvania; Baruch S. Blumberg Institute, Doylestown, Pennsylvania. Electronic address: timothy.block@bblumberg.org. 2. Hepatitis B Foundation, Doylestown, Pennsylvania; Baruch S. Blumberg Institute, Doylestown, Pennsylvania. Electronic address: ju-tao.guo@bblumberg.org.