title: Exosomes packaging APOBEC3G confer human immunodeficiency virus resistance to recipient cells.
abstract: The human cytidine deaminase APOBEC3G (A3G) is a part of a cellular defense system against human immunodeficiency virus type 1 (HIV-1) and other retroviruses. Antiretroviral activity of A3G can be severely blunted in the presence of the HIV-1 protein Vif. However, in some cells expressing the enzymatically active low-molecular-mass form of A3G, HIV-1 replication is restricted at preintegration steps, before accumulation of Vif. Here, we show that A3G can be secreted by cells in exosomes that confer resistance to both vif-defective and wild-type HIV-1 in exosome recipient cells. Our results also suggest that A3G is the major exosomal component responsible for the anti-HIV-1 activity of exosomes. However, enzymatic activity of encapsidated A3G does not correlate with the observed limited cytidine deamination in HIV-1 DNA, suggesting that A3G-laden exosomes restrict HIV-1 through a nonenzymatic mechanism. Real-time PCR quantitation demonstrated that A3G exosomes reduce accumulation of HIV-1 reverse transcription products and steady-state levels of HIV-1 Gag and Vif proteins. Our findings suggest that A3G exosomes could be developed into a novel class of anti-HIV-1 therapeutics.
authors.affiliation: Meharry Medical College, Center for AIDS Health Disparities Research, Nashville, Tennessee 37208, USA.
authors.forename: Atanu K
authors.initials: AK
authors.lastname: Khatua
authors.forename: Harry E
authors.initials: HE
authors.lastname: Taylor
authors.forename: James E K
authors.initials: JE
authors.lastname: Hildreth
authors.forename: Waldemar
authors.initials: W
authors.lastname: Popik
mesh_terms: D000071480:APOBEC-3G Deaminase; D002460:Cell Line; D003564:Cytidine Deaminase / Q000276:immunology*; D004279:DNA, Viral / Q000235:genetics / Q000378:metabolism; D055354:Exosomes / Q000276:immunology*; D015497:HIV-1 / Q000276:immunology*; D006801:Humans; D016133:Polymerase Chain Reaction; D014764:Viral Proteins / Q000096:biosynthesis; D014779:Virus Replication / Q000276:immunology
chemical_list: D004279:DNA, Viral; D014764:Viral Proteins; D000071480:APOBEC-3G Deaminase; C464924:APOBEC3G protein, human; D003564:Cytidine Deaminase