The interaction between native serum albumin and hepatitis B virus.

Purified hepatitis B virus particles were obtained from HBeAg positive serum by sucrose gradient ultracentrifugation and sephadex G-200 gel filtration. These virions formed a precipitation line in counterimmune electrophoresis with anti-albumin antibody, but the reaction could be inhibited by anti-HBs. After two months at 4 degrees C, another precipitating line was formed under the same condition which could not be inhibited by anti-HBs and was, thus, due to free albumin. When that sample was incubated at 37 degrees C overnight, the line of free albumin disappeared. The virion bound albumin was monomeric in non-denaturing gel electrophoresis. These results suggest that a reversible binding between virion and albumin may occur in vivo and does not require chemical modification or cross-linking.