The effects of hepatitis B virus core promoter mutations on hepatitis B core antigen distribution in hepatocytes as detected by laser-assisted microdissection.
OBJECTIVE
The severity of liver damage in patients with chronic hepatitis B is dependent on several factors such as subcellular localization of hepatitis B core antigen (HBcAg) and mutation of hepatitis B virus (HBV) DNA. Here we studied the interrelationship between these two factors both in situ and in vitro.


METHODS
Hepatocytes from liver biopsies showing expression of HBcAg only in the cytoplasm (n=6), only in the nucleus (n=4) and in both cytoplasms or nucleus of different hepatocytes (n=5) were picked up by laser-assisted microdissection and were checked for nucleotide sequences of core promoter region of HBV DNA. HepG2 and Huh7 cell lines transfected with wild and mutant HBV DNA were checked for localization of HBcAg.


RESULTS
The frequencies of core promoter mutations at nucleotide (nt) 1762 and nt 1764 was significantly higher in hepatocytes with cytoplasmic expression of HBcAg compared to that of nuclear expression of HBcAg (P<0.05). Cytoplasmic expression of HBcAg was observed more frequently in HepG2 and Huh7 cells transfected with HBV mutant type (nt 1762 and 1764) than HBV wild type (P<0.05).


CONCLUSIONS
Cytoplasmic localization of HBcAg was associated with HBV DNA mutations at nt 1762 and 1764.
Kawai
Keiko
K
Third Department of Internal Medicine, Ehime University School of Medicine, Shigenobu-Cho, Ehime 791-0295, Japan.
Horiike
Norio
N
Michitaka
Kojiro
K
Onji
Morikazu
M
D000293:Adolescent; D000328:Adult; D000368:Aged; D002478:Cells, Cultured; D003593:Cytoplasm / Q000821:virology; D004279:DNA, Viral / Q000032:analysis; D005260:Female; D006512:Hepatitis B Core Antigens / Q000235:genetics*; D006515:Hepatitis B virus / Q000235:genetics* / Q000302:isolation & purification; D019694:Hepatitis B, Chronic / Q000473:pathology* / Q000821:virology*; D022781:Hepatocytes / Q000473:pathology / Q000821:virology*; D006801:Humans; D007834:Lasers; D008297:Male; D042282:Microdissection; D008875:Middle Aged; D009154:Mutation; D011401:Promoter Regions, Genetic / Q000235:genetics; D014162:Transfection
D004279:DNA, Viral; D006512:Hepatitis B Core Antigens