Related Experiment Video
Updated: Aug 7, 2026
Peptide-based Identification of Functional Motifs and their Binding Partners
Published on: June 30, 2013
Interactions between Nef and AIP1 proliferate multivesicular bodies and facilitate egress of HIV-1
Luciana J Costa1, Nan Chen, Adriana Lopes
1Molecular Virology Laboratory, Dep. of Genetics, Federal University of Rio de Janeiro, Rio de Janeiro, Brazil. ljcosta@biologia.ufrj.br
Background:
Nef is an accessory protein of primate lentiviruses, HIV-1, HIV-2 and SIV. Besides removing CD4 and MHC class I from the surface and activating cellular signaling cascades, Nef also binds GagPol during late stages of the viral replicative cycle. In this report, we investigated further the ability of Nef to facilitate the replication of HIV-1.
Results:
To this end, first the release of new viral particles was much lower in the absence of Nef in a T cell line. Since the same results were obtained in the absence of the viral envelope using pseudo-typed viruses, this phenomenon was independent of CD4 and enhanced infectivity. Next, we found that Nef not only possesses a consensus motif for but also binds AIP1 in vitro and in vivo. AIP1 is the critical intermediate in the formation of multivesicular bodies (MVBs), which play an important role in the budding and release of viruses from infected cells. Indeed, Nef proliferated MVBs in cells, but only when its AIP1-binding site was intact. Finally, these functions of Nef were reproduced in primary macrophages, where the wild type but not mutant Nef proteins led to increased release of new viral particles from infected cells.
Conclusion:
We conclude that by binding GagPol and AIP1, Nef not only proliferates MVBs but also contributes to the egress of viral particles from infected cells.
Insights
The HIV accessory protein Nef enhances viral replication by binding GagPol and AIP1. This interaction promotes the formation of multivesicular bodies (MVBs), aiding viral particle release from infected cells.
Area of Science:
- Virology
- Molecular Biology
Background:
- Nef is an accessory protein crucial for primate lentiviruses like HIV-1.
- Nef influences viral replication by modulating cell surface proteins and signaling pathways.
- Nef interacts with GagPol during the later stages of the viral life cycle.
Purpose of the Study:
- To further investigate the role of Nef in facilitating HIV-1 replication.
- To elucidate the mechanisms by which Nef enhances viral particle release.
Main Methods:
- Assessed viral particle release in T cell lines and primary macrophages with and without Nef.
- Utilized pseudotyped viruses to determine CD4 independence of Nef's function.
- Investigated Nef's interaction with AIP1 in vitro and in vivo using binding assays.
- Examined the effect of Nef on multivesicular body (MVB) formation.
- Compared the function of wild-type Nef with mutant Nef proteins.
Main Results:
- Viral particle release was significantly reduced in the absence of Nef.
- Nef's role in enhancing viral release was independent of CD4 and viral envelope.
- Nef binds to AIP1, a key factor in multivesicular body (MVB) formation.
- Nef promotes MVB proliferation, contingent on its intact AIP1-binding site.
- These findings were replicated in primary macrophages, showing increased viral particle release with wild-type Nef.
Conclusions:
- Nef binding to GagPol and AIP1 is essential for its function.
- Nef promotes multivesicular body (MVB) proliferation.
- Nef significantly contributes to the egress of viral particles from infected cells.
Related Concept Videos
01:19Inhibitors of Virion Maturation and Assembly
01:38Intralumenal Vesicles and Multivesicular Bodies