Expression of Hepatitis B Virus Core Antigen Gene Is Induced in Human Hepatoma Cells by Their Growth in Nude Mice

Comparative Expression of Hepatitis B Virus Antigens in Several Cell Model Systems

“…Passage of the human cell lines in nude mice and subsequent reculturing of the tumour tissue did not lead to any e antigen expression, whereas e antigen was detected in vivo and in vitro in both experimental cell lines (Tables 3, 4 and 5). We conclude that the functional state of the HBV genome does not depend on the environment, as has been suggested by Marquardt et al (1984), since HBV gene expression in the tumour homogenates and tumour derived cell lines did not differ from that measured in the parental cell lines.…”

“…Since it has been shown that expression of HBV DNA integrated into host cell chromosomes is inducible by changes in the environment (Marquardt et al, 1984), we investigated HBV gene expression in all the cell systems when grown as tumours in nude mice as well as in cell lines subsequently derived from these tumours, thus comparing HBV gene expression in vitro and in vivo.…”

Hepatitis B virus components produced by the human hepatoma cell line PLC/PRF/5: Do they indicate virus propagation?

“…This is explained on the molecular level by the integration of HBV sequences, including at least one functionally active HBsAg-encoding genc (14), into chromosomes. But the cell line exhibits simultaneously an indication of productive ini~ction (43) when it is treated with 5'-azacytidine or grown as a nude mouse tumour, i. e. production of HBc/eAg-specific protein (37,64). Moreover, the presence of a particle-bound DNA polymerase activity (Fig.…”

“…The agent is known to prevent cytidine methylation (28,47) and thus may cause the expression of otherwise silent HBcAg genes. The production of HBc or eAG-specific protein has also been achieved by culture of the cells as nude mouse tumours (37). The cells do not stably acquire the property to produce such proteins since tumour cells subsequently cultured in vitro are again HBc/eAg-negative.…”

“…Such particles sed'tment at 95 S and exhibit a buoyant density in CsC1 of 1.37-1.38 g/ml (26). as nude mouse tumours, harvested and homogenized as described earlier (37). Material which is eontMned in the cell cytoplasm after centrifugation for 30 minutes at 40,000 × g was submitted to sucrose gradient eentrifugation (A) or CsC1 density gradient eentrifugation (B) as described earlier (65).…”