TY - JOUR
T1 - Cellular uptake of avian leukosis virus subgroup B is mediated by clathrin
AU - Diaz-Griffero, Felipe
AU - Jackson, Antony P.
AU - Brojatsch, Jürgen
PY - 2005/6/20
Y1 - 2005/6/20
N2 - Avian leukosis virus (ALV) requires endocytosis and a low pH step for successful viral entry. Here we report that transient treatment with lysosomotropic agents was not sufficient to block ALV subgroup B (ALV-B) entry, while it completely inhibited uptake of the pH-dependent Semliki Forest virus. Extended incubations with lysosomotropic agents were required to block ALV-B entry, suggesting that ALV particles are stable in endosomal compartments. We analyzed endocytic pathways involved in the uptake of ALV-B into target cells. The ALV-B receptor TVBS3 was not associated with detergent-resistant membranes (DRMs) in the presence or absence of ALV-B particles. This result suggested that DRM-associated endocytic pathways were not required for ALV-B entry. Using several approaches, we found that clathrin mediates endocytosis of ALV-B particles into target cells. By means of confocal microscopy, we established that the ALV-B receptor TVBS3 colocalized with clathrin in TVBS3-expressing quail QT-6 cells. In addition, chlorpromazine, an inhibitor of clathrin-mediated endocytosis, blocked uptake of soluble ALV-B Env into chicken embryo fibroblasts. To examine ALV-B uptake into clathrin-negative cells, we used a chicken DT40 B cell line containing a tetracycline-regulatable clathrin gene. Clathrin depletion significantly reduced ALV-B entry into the chicken DT40 cell line. Taken together, our results suggest that clathrin is involved in uptake of ALV-B particles into target cells.
AB - Avian leukosis virus (ALV) requires endocytosis and a low pH step for successful viral entry. Here we report that transient treatment with lysosomotropic agents was not sufficient to block ALV subgroup B (ALV-B) entry, while it completely inhibited uptake of the pH-dependent Semliki Forest virus. Extended incubations with lysosomotropic agents were required to block ALV-B entry, suggesting that ALV particles are stable in endosomal compartments. We analyzed endocytic pathways involved in the uptake of ALV-B into target cells. The ALV-B receptor TVBS3 was not associated with detergent-resistant membranes (DRMs) in the presence or absence of ALV-B particles. This result suggested that DRM-associated endocytic pathways were not required for ALV-B entry. Using several approaches, we found that clathrin mediates endocytosis of ALV-B particles into target cells. By means of confocal microscopy, we established that the ALV-B receptor TVBS3 colocalized with clathrin in TVBS3-expressing quail QT-6 cells. In addition, chlorpromazine, an inhibitor of clathrin-mediated endocytosis, blocked uptake of soluble ALV-B Env into chicken embryo fibroblasts. To examine ALV-B uptake into clathrin-negative cells, we used a chicken DT40 B cell line containing a tetracycline-regulatable clathrin gene. Clathrin depletion significantly reduced ALV-B entry into the chicken DT40 cell line. Taken together, our results suggest that clathrin is involved in uptake of ALV-B particles into target cells.
KW - Avian leukosis virus subgroup B
KW - Caveolae
KW - Clathrin
KW - Endocytosis
KW - Entry
KW - pH-dependence
UR - http://www.scopus.com/inward/record.url?scp=19444368439&partnerID=8YFLogxK
UR - http://www.scopus.com/inward/citedby.url?scp=19444368439&partnerID=8YFLogxK
U2 - 10.1016/j.virol.2005.02.027
DO - 10.1016/j.virol.2005.02.027
M3 - Article
C2 - 15914219
AN - SCOPUS:19444368439
SN - 0042-6822
VL - 337
SP - 45
EP - 54
JO - Virology
JF - Virology
IS - 1
ER -