Related Experiment Video
Updated: Jul 20, 2026
07:10
Conformational Evaluation of HIV-1 Trimeric Envelope Glycoproteins Using a Cell-based ELISA Assay
Published on: September 14, 2014
Human ESCRT-II complex and its role in human immunodeficiency virus type 1 release
Charles Langelier1, Uta K von Schwedler, Robert D Fisher
1Department of Biochemistry, 15 N. Medical Drive East, Room 4100, University of Utah School of Medicine, Salt Lake City, UT 84112-5650, USA.
Journal of Virology
|September 16, 2006
Summary
Human ESCRT-II proteins interact with components of the multivesicular body (MVB) pathway. However, HIV-1 release and infectivity are not affected by ESCRT-II depletion, suggesting alternative viral budding pathways.
Area of Science:
- Cell Biology
- Virology
- Molecular Biology
Background:
- Enveloped RNA virus budding, including HIV-1, utilizes cellular machinery similar to multivesicular body (MVB) vesicle formation.
- The ESCRT-II complex in yeast is crucial for MVB protein sorting and vesicle formation, bridging ESCRT-I and ESCRT-III complexes.
Purpose of the Study:
- To investigate the function of human ESCRT-II subunits (EAP20, EAP30, EAP45) in MVB vesicle formation and HIV-1 budding.
- To determine if HIV-1 release relies on the ESCRT-II pathway.
Main Methods:
- Biochemical assays to assess subunit interactions (ubiquitin binding, TSG101/ESCRT-I, CHMP6/ESCRT-III binding).
- Cellular localization studies (endosomal membranes, VPS4-dependent localization).
- Functional assays using small interfering RNA (siRNA) to deplete ESCRT-II and CHMP6/ESCRT-III, assessing epidermal growth factor receptor (EGFR) downregulation and HIV-1 release/infectivity.
Main Results:
- Human ESCRT-II subunits exhibit conserved properties with yeast orthologs, including ubiquitin binding and interactions with ESCRT-I and ESCRT-III components.
- Human ESCRT-II localizes to endosomal membranes in a VPS4-dependent manner.
- Depletion of human ESCRT-II or CHMP6/ESCRT-III partially impaired EGFR downregulation but did not affect HIV-1 release or infectivity.
Conclusions:
- Human ESCRT-II plays a role in MVB-related cellular processes, such as EGFR downregulation.
- HIV-1 release and infectivity are independent of the ESCRT-II pathway, indicating the existence of alternative viral budding mechanisms.
Related Concept Videos
01:19Inhibitors of Virion Maturation and Assembly
As part of their replication cycle, certain viruses synthesize long precursor proteins called polyproteins within infected host cells. In human immunodeficiency virus (HIV), two major polyproteins are produced: Gag and Gag-Pol. The Gag polyprotein supplies the structural components of the virus, while Gag-Pol includes essential viral enzymes such as reverse transcriptase, integrase, and protease. After synthesis, these polyproteins move to the host cell membrane, where they assemble into an...
01:38Intralumenal Vesicles and Multivesicular Bodies
Intraluminal vesicles (ILVs) are small vesicles 50-80 nm in diameter formed during the maturation of early endosomes. A specialized endosome containing numerous ILVs is called a multivesicular body (MVB). ILVs contain internalized molecules such as antigens, nucleic acids, proteins, and metabolites. Some of these molecules are released from the MVBs inside exosomes and are transported to other cells. Other MVBs contain molecules that are retained in the ILVs and are later degraded within the...
01:25Inhibitors Of Virion Release
Viral replication and dissemination rely on efficient mechanisms for host cell entry, genome replication, assembly, and release. Influenza viruses, such as types A and B, are negative-sense single-stranded RNA viruses with a segmented genome, that depend on two critical surface glycoproteins to carry out these processes: hemagglutinin (HA) and neuraminidase (NA). HA initiates infection by binding to sialic acid residues on the surface of host epithelial cells, facilitating receptor-mediated...
01:29Immune Response Against Viral Pathogens
The immune system's response to viral infections is a complex and coordinated process involving natural killer (NK) cells, T cell-mediated responses, and antibody-mediated responses.
NK Cells
NK cells are a crucial part of our innate immune system, acting as the first line of defense against viral infections. These cells can recognize and kill infected cells without prior exposure to the virus, effectively slowing down the spread of infection. Additionally, NK cells produce proinflammatory...
NK Cells
NK cells are a crucial part of our innate immune system, acting as the first line of defense against viral infections. These cells can recognize and kill infected cells without prior exposure to the virus, effectively slowing down the spread of infection. Additionally, NK cells produce proinflammatory...
02:33Retroviruses
Retroviruses and retrotransposons both insert copies of their genetic elements into the genome of the host cell. Thus, the viral genes are passed on when the host genome is replicated or translated. A typical retroviral DNA sequence contains 3-4 genes that encode the different proteins required for its structural assembly and function as a molecular parasite. This DNA is transcribed into a single mRNA, which is very similar in structure to conventional mRNAs, i.e., it is capped at the 5’...
01:26Size and Structure of Viral Genomes
Viral genomes exhibit remarkable diversity in size, structure, and composition, influencing their replication strategies and interactions with host cells. These genomes consist of either DNA or RNA and may be linear or circular. Additionally, they can be single-stranded or double-stranded, with each configuration affecting how the virus propagates within a host. RNA viruses, for instance, generally have smaller genomes than DNA viruses, a factor that contributes to their high mutation rates and...