Antibodies in Anti-HBe—positive patient sera bind to an HBe protein expressed on the cell surface of human hepatoma cells: Implications for virus clearance
✍ Scribed by Hans-jürgen Schlicht; Albrecht von Brunn; Lorenz Theilmann
- Publisher
- John Wiley and Sons
- Year
- 1991
- Tongue
- English
- Weight
- 503 KB
- Volume
- 13
- Category
- Article
- ISSN
- 0270-9139
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✦ Synopsis
The relevance of the recently described membranebound form of the HBe protein for the antiviral immune response was examined. The data show that antibodies in anti-€€Be, but not in anti-HBc-positive human sera efficiently bind to the membrane expressed HBe. No evidence was obtained that the HBc can reach the cell surface in a form that can be detected with human antibodies. The findings suggest that the decline of virus titer that is usually observed after seroconversion from HBe to anti-HBe might be the result of an antibody-mediated elimination of infected cells. (HEPATOLOGY 1991;13:57-61.)
As has been demonstrated by biochemical and genetic analyses, the HBV core gene encodes at least two different proteins: the HBc, which forms the virus capsid, and the HBe, which is secreted from infected liver cells and is found in a free form in the serum (1,2). This is because the HBe is derived from a protein slightly larger than the HBc that, in addition to the HBc sequences, contains a signal sequence for secretion and therefore enters the secretory pathway (3, 4). Nterminal and C-terminal proteolytic processing of this protein then results in HBe formation (2, 5 ) .
Clinical observations have shown that seroconversion from HBe to anti-HBe represents a crucial step during HBV infection, whereas the humoral immune response directed against the HBc appears to be insignificant ( 6 ) . Anti-HBc antibodies appear very early after infection and persist for a long time but have no obvious effect on the course of the disease because all patients develop such antibodies, irrespective of whether they clear the virus or not. On the contrary, appearance of anti-HBe usually correlates with complete or extensive elimination of virus. Interestingly, seroconversion from HBe