The association of CD81 with tetraspanin-enriched microdomains is not essential for Hepatitis C virus entry.
BACKGROUND
Three percent of the world's population is chronically infected with hepatitis C virus (HCV) and thus at risk of developing liver cancer. Although precise mechanisms regulating HCV entry into hepatic cells are still unknown, several cell surface proteins have been identified as entry factors for this virus. Among these molecules, the tetraspanin CD81 is essential for HCV entry. Interestingly, CD81 is also required for Plasmodium infection. A major characteristic of tetraspanins is their ability to interact with each other and other transmembrane proteins to build tetraspanin-enriched microdomains (TEM).


RESULTS
In our study, we describe a human hepatoma Huh-7 cell clone (Huh-7w7) which has lost CD81 expression and can be infected by HCV when human CD81 (hCD81) or mouse CD81 (mCD81) is ectopically expressed. We took advantage of these permissive cells expressing mCD81 and the previously described MT81/MT81w mAbs to analyze the role of TEM-associated CD81 in HCV infection. Importantly, MT81w antibody, which only recognizes TEM-associated mCD81, did not strongly affect HCV infection. Furthermore, cholesterol depletion, which inhibits HCV infection and reduces total cell surface expression of CD81, did not affect TEM-associated CD81 levels. In addition, sphingomyelinase treatment, which also reduces HCV infection and cell surface expression of total CD81, raised TEM-associated CD81 levels.


CONCLUSIONS
In contrast to Plasmodium infection, our data show that association of CD81 with TEM is not essential for the early steps of HCV life cycle, indicating that these two pathogens, while using the same molecules, invade their host by different mechanisms.
Rocha-Perugini
Vera
V
Institut de Biologie de Lille, CNRS-UMR8161, Université Lille Nord de France, Institut Pasteur de Lille, Lille, France. vera.rocha.perugini@gmail.com
Lavie
Muriel
M
Delgrange
David
D
Canton
Jonathan
J
Pillez
André
A
Potel
Julie
J
Lecoeur
Cécile
C
Rubinstein
Eric
E
Dubuisson
Jean
J
Wychowski
Czeslaw
C
Cocquerel
Laurence
L
D000818:Animals; D015703:Antigens, CD / Q000378:metabolism*; D019921:Biotinylation; D045744:Cell Line, Tumor; D002462:Cell Membrane / Q000821:virology; D002518:Ceramides / Q000378:metabolism; D002784:Cholesterol / Q000378:metabolism; D016174:Hepacivirus / Q000235:genetics / Q000276:immunology / Q000502:physiology*; D006508:Hepatitis Antibodies / Q000378:metabolism; D006526:Hepatitis C / Q000821:virology; D006801:Humans; D021962:Membrane Microdomains / Q000821:virology; D008565:Membrane Proteins / Q000378:metabolism*; D051379:Mice; D009500:Neutralization Tests; D013108:Sphingomyelin Phosphodiesterase / Q000378:metabolism; D060225:Tetraspanin 28; D053586:Virus Internalization
D015703:Antigens, CD; C554798:CD81 protein, human; C554799:Cd81 protein, mouse; D002518:Ceramides; D006508:Hepatitis Antibodies; D008565:Membrane Proteins; D060225:Tetraspanin 28; D002784:Cholesterol; D013108:Sphingomyelin Phosphodiesterase