In vitro binding of hepatitis C virus to CD81-positive and -negative human cell lines.
OBJECTIVE
The aim of the present study is to study the mechanism of entry of hepatitis C virus (HCV) into human cells. We examined the in vitro binding of HCV to various human cell lines with or without CD81 expression.


METHODS
We first used three cell lines, two hepatocyte-derived, huH-7 and HepG2, and one colon cancer cell line, Cw2. Among them, HepG2 did not express TAPA-1 (CD81) on their surface but two others did. They were incubated with HCV + serum for 1 h and HCV-RNA in extracted RNA obtained from these cells was examined by using both a quantitative test and reverse transcriptase-polymerase chain reaction (RT-PCR).


RESULTS
We found that a significant amount of HCV-RNA was detected in huH-7 and HepG2 but not in Cw2. In addition, the titer of HCV-RNA in serum-incubated CD81-transfected HepG2 was similar to that of the non-transfected titer, and the binding between HCV and huH-7 was not inhibited by anti-CD81. Under the same condition, HCV-RNA tended to be detectable in serum-pulsed hepatocyte-derived cell lines, but not in the others.


CONCLUSIONS
These results suggest that while CD81, as reported, specifically binds to HCV-E2 protein, the entry of HCV into human hepatocytes might be regulated by CD81-unrelated molecule(s).
Sasaki
Mina
M
Division of Medicine, Institute of Gastroenterology, Tokyo Women's Medical University, Institute of Medical Science, University of Tokyo, Tokyo, Japan.
Yamauchi
Katsumi
K
Nakanishi
Toshimi
T
Kamogawa
Yumiko
Y
Hayashi
Naoaki
N
D000906:Antibodies / Q000494:pharmacology; D015703:Antigens, CD / Q000235:genetics / Q000276:immunology / Q000378:metabolism*; D002460:Cell Line; D004198:Disease Susceptibility; D016174:Hepacivirus / Q000235:genetics / Q000502:physiology*; D022781:Hepatocytes / Q000737:chemistry; D006801:Humans; D008565:Membrane Proteins / Q000235:genetics / Q000276:immunology / Q000378:metabolism*; D012367:RNA, Viral / Q000032:analysis; D060225:Tetraspanin 28; D014162:Transfection
D000906:Antibodies; D015703:Antigens, CD; C554798:CD81 protein, human; D008565:Membrane Proteins; D012367:RNA, Viral; D060225:Tetraspanin 28