Cellular uptake of avian leukosis virus subgroup B is mediated by clathrin

Virology. 2005 Jun 20;337(1):45-54. doi: 10.1016/j.virol.2005.02.027.

Abstract

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 TVB(S3) 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 TVB(S3) colocalized with clathrin in TVB(S3)-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.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Animals
  • Avian Leukosis Virus / classification
  • Avian Leukosis Virus / physiology*
  • Chick Embryo
  • Clathrin / physiology*
  • Endocytosis*
  • Endosomes / virology
  • Fibroblasts / virology*
  • Hydrogen-Ion Concentration

Substances

  • Clathrin