title: Infectious bursal disease virus uptake involves macropinocytosis and trafficking to early endosomes in a Rab5-dependent manner.
abstract: Infectious bursal disease virus (IBDV) internalization is sparsely known in terms of molecular components of the pathway involved. To describe the cell biological features of IBDV endocytosis, we employed perturbants of endocytic pathways such as pharmacological inhibitors and overexpression of dominant-negative mutants. Internalization analysis was performed quantifying infected cells by immunofluorescence and Western blot detection of the viral protein VP3 at 12 h post-infection reinforced by the analysis of the capsid protein VP2 localization after virus uptake at 1 h post-infection. We compared IBDV infection to the internalization of well-established ligands with defined endocytic pathways: transferrin, cholera-toxin subunit B and dextran. To describe virus endocytosis at the morphological level, we performed ultrastructural studies of viral internalization kinetics in control and actin dynamics-blocked cells. Our results indicate that IBDV endocytic internalization was clathrin- and dynamin-independent, and that IBDV uses macropinocytosis as the primary entry mechanism. After uptake, virus traffics to early endosomes and requires exposure to the low endocytic pH as well as a functional endocytic pathway to complete its replication cycle. Moreover, our results indicate that the GTPase Rab5 is crucial for IBDV entry supporting the participation of the early endosomal pathway in IBDV internalization and infection of susceptible cells.
authors.affiliation: Facultad de Farmacia y Bioquímica, Universidad Juan Agustín Maza, Mendoza, Argentina.|Instituto de Histología y Embriología (IHEM), Facultad de Ciencias Médicas, Universidad Nacional de Cuyo - CONICET, Mendoza, Argentina.
authors.forename: María C
authors.initials: MC
authors.lastname: Gimenez
authors.affiliation: Departamento de Biología Molecular y Celular, Centro Nacional de Biotecnología - CSIC, Madrid, Spain.
authors.forename: José F
authors.initials: JF
authors.lastname: Rodríguez Aguirre
authors.affiliation: Facultad de Farmacia y Bioquímica, Universidad Juan Agustín Maza, Mendoza, Argentina.|Instituto de Histología y Embriología (IHEM), Facultad de Ciencias Médicas, Universidad Nacional de Cuyo - CONICET, Mendoza, Argentina.
authors.forename: María I
authors.initials: MI
authors.lastname: Colombo
authors.affiliation: Facultad de Farmacia y Bioquímica, Universidad Juan Agustín Maza, Mendoza, Argentina.|Instituto de Histología y Embriología (IHEM), Facultad de Ciencias Médicas, Universidad Nacional de Cuyo - CONICET, Mendoza, Argentina.|Facultad de Ciencias Exactas y Naturales, Universidad Nacional de Cuyo, Mendoza, Argentina.
authors.forename: Laura R
authors.initials: LR
authors.lastname: Delgui
mesh_terms: D000818:Animals; D001692:Biological Transport; D001717:Birds; D015153:Blotting, Western; D002460:Cell Line; D011992:Endosomes / Q000821:virology*; D007243:Infectious bursal disease virus / Q000502:physiology*; D008856:Microscopy, Fluorescence; D010873:Pinocytosis; D013997:Time Factors; D015678:Viral Structural Proteins / Q000032:analysis; D053586:Virus Internalization; D020696:rab5 GTP-Binding Proteins / Q000378:metabolism*
chemical_list: D015678:Viral Structural Proteins; D020696:rab5 GTP-Binding Proteins