Immunofluorescent localization of hepatitis B antigens in chimpanzee tissues

Three chimpanzee chronic carriers of hepatitis B surface antigen (HBs Ag) were examined by immunofluorescent techniques to determine the localization of HBs Ag and hepatitis B core antigen (HBc Ag) in their tissues. All specimens were quick-frozen in liquid nitrogen and stored at -70degrees until sectioned. Frozen sections were prepared and stained for examination by fluorescent microscopy. For staining, anti-HBs and anti-HBc labeled with fluorescein isothiocyanate were used. HBs Ag was found in the liver of all three animals. In two animals which were necropsied, HBs Ag was detected in other tissues, e.g., lymph nodes, spleen, and kidney. Specificity of these tests was demonstrated by blocking with purified HBs Ag. Examination of various tissues revealed HBc Ag only in the liver. 32 samples of liver, from different sites from one chimpanzee, were examined and all were positive for both HBs Ag and HBc Ag. The finding of HBc Ag only in the liver further supports the assertion that the liver is the sole site of replication of hepatitis B virus in chronic carriers.