SPECIES-SPECIFICITY FOR HBSAG BINDING-PROTEIN ENDONEXIN-II

Background/Aims: Hepatitis B virus displays a distinct species and tis sue tropism, Previously we have demonstrated that a human liver plasma membrane protein,vith a molecular weight of approximately 34 kiloDalt on specifically binds to HBsAg. This protein was identified as endonex in II, a Ca2+ dependent phospholipid binding protein. Methods: Using a mouse monoclonal antibody, directed against the HBsAg binding epitope on human endonexin II, liver tissue from various nonhuman species, hu man liver tissue and some extrahepatic human tissues were screened for the presence of endonexin II. Results: Endonexin II was detectable in human, chimpanzee and rhesus monkey liver and in all tested extra-hep atic human tissues, using western blot and inmunohistochemical techniq ues, In rat, mouse, cow and pig liver tissues endonexin II could not b e detected with the antibody. Conclusions: The species specific distri bution of the HBsAg binding protein endonexin II apparently correlates with the species tropism of hepatitis B virus. Furthermore, the detec tion of HBV-DNA, RNA transcripts and antigens in a variety of tissues in chronic infected patients, is in agreement with the wide distributi on of the HBsAg binding endonexin II in various tissues.