[Culture of hepatitis virus B]

For the last 25 years, numerous attempts have been made to isolate the HBV agent responsible for hepatitis B by means of cultures 'in vitro'. We have undertaken longterm cultures of children's hepatic tissue (C.H.), conjunctive tissue (human adult H.A.F. and human embryonic fibroblasts H.E.F.) and KB cells; these were put in the presence of 7 sera HB + rich in Dane particles. These cells were trypsinized twice a week for almost 3 months and did not present any cytopathogenic effects. Electromicroscopy revealed, 15 days after infection, the presence of icosahedral particles (25 to 27 nm in diameter), free or in dense clusters, but more often empty (20 nm in diameter). These structures seemed to be made up of an assembly of capsomers approximately 5 nm in diameter, joined together in fours to form a ridge. Older cultures revealed clusters of icosahedrons some of which degenerated spontaneously; others were surrounded by proteinic structure having a fringed aspect. Certain rare particles of 35 to 45 nm in diameter are similar to full Dane particles. EID immunological results were positive in the case of sera of patients convalescent from hepatitis B, containing anti-HBc antibodies, on C.H. cells the 27th and 40th days, and negative with anti-HBs antibodies. By immunofluorescence we observed 12 to 20 days after infection of the cells, a clear fluorescence at first nuclear, then essentially cytoplasmic, by means of fluorescent anti-HBc sera of human or animal origin. With the fluorescent anti-HBs antibodies, the reaction is weak and solely cytoplasmic although in DRI, with H.E.F. and KB cells, we obtained from time to time weakly positive results in HBs. The relations between the morphological structures and the immunological results observed are discussed.