title: Major histocompatibility complex class II molecules promote human immunodeficiency virus type 1 assembly and budding to late endosomal/multivesicular body compartments.
abstract: Human immunodeficiency virus type 1 (HIV-1) assembly, budding, and release occur mostly at the plasma membrane in T lymphocytes as well as in established nonlymphoid cell lines, while in macrophages these processes occur primarily in intracellular compartments that harbor late endosomal/multivesicular body (LE/MVB) markers, including human leukocyte antigen DR (HLA-DR). Major histocompatibility complex class II molecules (MHC-II), which are expressed in macrophages and activated T cells, have been previously reported to induce the formation of multilaminar and multivesicular endocytic MHC-II-like structures analogous to MVB upon their expression in HEK 293 cells. Here, we have examined the role of MHC-II in HIV-1 Gag targeting as well as in virus assembly and release. Expression of HLA-DR in nonlymphoid cell lines induced a relocation of Gag to intracellular compartments that harbored LE/MVB markers and increased the accumulation of viral particles assembling intracellularly. Consequently, viral production and release from the cell surface was found to be substantially decreased in HLA-DR-expressing cells. This process was specific, since it was not observed with HLA-DR molecules lacking their cytoplasmic tails, nor with structurally related but functionally distinct MHC-II molecules such as HLA-DM or HLA-DO. Importantly, virus released intracellularly in HLA-DR-expressing cells retained infectivity. Overall, these results suggest a role of MHC-II molecules in promoting HIV-1 assembly and budding to LE/MVB and raise the possibility that this activity might be part of a normal pathway of virus production in cell types physiologically expressing MHC-II molecules, such as macrophages.
authors.affiliation: Unité de Rétrovirologie Humaine, Institut de Recherches Cliniques de Montréal, Montréal, Canada.
authors.forename: Andrés
authors.initials: A
authors.lastname: Finzi
authors.forename: Alexandre
authors.initials: A
authors.lastname: Brunet
authors.forename: Yong
authors.initials: Y
authors.lastname: Xiao
authors.forename: Jacques
authors.initials: J
authors.lastname: Thibodeau
authors.forename: Eric A
authors.initials: EA
authors.lastname: Cohen
mesh_terms: D002460:Cell Line; D011992:Endosomes / Q000276:immunology*; D015683:Gene Products, gag / Q000276:immunology; D015497:HIV-1 / Q000502:physiology* / Q000648:ultrastructure; D000949:Histocompatibility Antigens Class II / Q000276:immunology*; D006801:Humans; D046529:Microscopy, Electron, Transmission; D013997:Time Factors; D014771:Virion / Q000378:metabolism; D019065:Virus Assembly
chemical_list: D015683:Gene Products, gag; D000949:Histocompatibility Antigens Class II