Membrane traffic pathways in viral replication and pathogenesis

Lead Research Organisation: University College London

Abstract

"We study the human immunodeficiency virus (HIV) that is linked to AIDS and is believed to have infected 60 million people worldwide. During infection these viruses must interact with receptor proteins expressed on the surfaces of target cells. Using the natural binding proteins of these receptors, it is possible to abrogate HIV infection. We are trying to understand the cellular and molecular mechanisms that underlie this regulation with the aim of developing novel strategies to down regulate the receptors. Such strategies may have efficacy against HIV. Importantly, the receptors exploited by HIV are representative of a large class of similar proteins, so-called G protein coupled receptors (GPCRs), that control a range of biological functions including the immune system. So what we learn about HIV receptors may have relevance to other important biological events.||In addition to understanding virus entry, we also investigate the molecular and cellular mechanisms involved in the formation of new virus particles within infected cells. This requires that the key structural proteins that make up virus particles are bought together at the same time and place within an infected cell so that virus particles can form. We have identified molecular signals in the envelope glycoprotein that are required for the correct trafficking within infected cells. When one of these signals is mutated in a simian model system, the virus is attenuated and is no longer pathogenic. Moreover, animals treated with this virus are protected against challenge with normal pathogenic viruses. Together these studies are providing novel insights to the mechanisms of pathogenesis and may give hints to the key components of immune control."

Technical Summary

We focus on understanding; (i) the mechanisms controlling cell surface expression of cellular receptors for HIV and (ii) the mechanisms involved in the assembly of HIV virions.||Project 1: Human immunodeficiency virus (HIV), the etiological agent of AIDS, infects cells by membrane fusion following interaction with receptors expressed on surfaces of target cells. Two different cell surface glycoproteins form the functional virus receptor - CD4 and a member of the chemokine receptor family of G protein-coupled receptors (GPCRs). Two chemokine receptors have been linked to HIV infection, CC chemokine receptor 5 (CCR5) and CXC chemokine receptor 4 (CXCR4). The agonists for these receptors can protect cells from infection by inducing their endocytosis. We are studying the mechanism of chemokine receptor internalisation and the fate of the internalised molecules. Although focused on chemokine receptors, these studies have relevance for understanding the regulation of a variety of other GPCRs.||Project 2: To make new HIV particles, the essential proteins of the virus must be bought together at the same time and place within infected cells. Structurally, HIV is a relatively simple virus and requires just three virally encoded proteins to make new infectious particles, namely Envelope (Env), Gag and Gag-Pol. We are trying to understand how these proteins are sorted and traffic within cells in order to produce viral particles. We have found that in primary human macrophages, infected with HIV in tissue culture, the assembly events occur on the membranes of a novel intracellular multivesicular compartment. This internal assembly may convey distinct biochemical and functional properties on virus particles and enable release of infectious virus to be regulated and coordinated with the presence of appropriate target cells, such as CD4 positive T cells. Experiments are in progress to determine how the viral components target this compartment and the normal biological functions of this compartment. Significantly, we have found that the Env protein contains conserved signals that control its intracellular trafficking, in part these signals mediate endocytosis and keep the level of Env expressed at the cell surface low. Significantly, in a monkey model, mutation of these signals in the closely related simian immunodeficiency viruses (SIV) leads to attenuation of the pathological potential of the virus. Moreover, animals treated with such viruses show protection when challenged with pathogenic viruses. We hypothesis that correct signals in the structural components of the virus are required to allow efficient assembly of infectious virions and that in animals challenged with viruses lacking the correct signals in the viral structural proteins, the immune system is able to control infection and protect against challenge with non-attenuated viruses.
 
Description Role of SIV and HIV Env cytoplasmic tail in pathogenesis and protective immunity
Amount £276,611 (GBP)
Funding ID 1RO1A/138782-01 
Organisation National Institutes of Health (NIH) 
Sector Public
Country United States
Start 07/2018 
End 06/2022
 
Description UCL MRC Confidence in Concepts
Amount £100,000 (GBP)
Funding ID MC_PC_15037 
Organisation Medical Research Council (MRC) 
Sector Public
Country United Kingdom
Start 08/2016 
End 07/2017
 
Description UCL Therapeutic Innovation Fund
Amount £100,000 (GBP)
Organisation University College London 
Sector Academic/University
Country United Kingdom
Start 09/2014 
End 08/2015
 
Description Dr Marcus Dorner, Imperial College 
Organisation Imperial College London
Country United Kingdom 
Sector Academic/University 
PI Contribution Provided data and expertise on the effect of Hsp90 on regulation of HIV-1 latency, provided specific Hsp90 inhibitor.
Collaborator Contribution humanized mouse models for HIV-1 infection to test the effect of selective Hsp90 inhibitors on HIV-1 latency.
Impact experiments ongoing.
Start Year 2014
 
Description Dr. Richard Benarous, Mutabilis, France 
Organisation University College London
Department Metbolism and Endocrinology
Country United Kingdom 
Sector Academic/University 
PI Contribution Performed novel high through put screening to identify host factors necessary for HIV-1 replication.
Collaborator Contribution Provided expertise and library of 10,000 small chemical compounds selected from a 150,000 compounds library.
Impact Identified four new compounds with antiretroviral activity: they belong to a new class of antiretrovirals.
Start Year 2012
 
Description Env trafficking signals in SIV pathogenesis 
Organisation University of Pennsylvania
Department Perelman School of Medicine
Country United States 
Sector Academic/University 
PI Contribution Cell biological analysis of the role of trafficking signals in the cytoplasmic domain of the simian immunodeficiency virus envelope protein - a model for understanding HIV pathogenesis and anti-viral immune responses.
Collaborator Contribution Virological and in vivo studies that complement the cell biology.
Impact Nine publications Multi-disciplinary: Virology, cell biology, in vivo animal models
 
Description MRCT Index Compound Set 
Organisation MRC-Technology
Country United Kingdom 
Sector Private 
PI Contribution High-throughput screening of small molecule compounds"
Collaborator Contribution "Provision of small molecule library"
Impact None to date
Start Year 2015
 
Description Mode of action of HIV replication inhibitor: CADA 
Organisation University of Leuven
Country Belgium 
Sector Academic/University 
PI Contribution My lab contributed to understanding that CADA can specifically down regulate human CD4 by inhibiting the synthesis of the molecule.
Collaborator Contribution The partners were able to show that CADA can reversibly bind the signal peptide of the nascent human CD4 within the ER translocon and thereby inhibit synthesis of new protein.
Impact A paper is in press in PLOS Biology, other abstracts have been published in meeting reports.
Start Year 2010
 
Description Regulation of GPCR signalling through endocytic trafficking 
Organisation University of California, San Francisco
Country United States 
Sector Academic/University 
PI Contribution My group has provided conceptual input to the work, as well as electron microscopy, data analysis and contributions to the writing of research papers.
Collaborator Contribution The partners have provided conceptual input to the work, as well as live cell imaging, data analysis and contributions to the writing of research papers.
Impact Two papers have been published to date.
Start Year 2010
 
Description Contribution to the Financial Times New synthetic life needs context and regulation. 
Form Of Engagement Activity A magazine, newsletter or online publication
Part Of Official Scheme? No
Geographic Reach International
Primary Audience Public/other audiences
Results and Impact -
Year(s) Of Engagement Activity 2010
URL http://www.ft.com/cms/s/0/3da6db20-6796-11df-a932-00144feab49a.html#axzz2hsOEkNfY
 
Description European Union Marie Curie Alumni Association 
Form Of Engagement Activity A formal working group, expert panel or dialogue
Part Of Official Scheme? Yes
Geographic Reach International
Primary Audience Other academic audiences (collaborators, peers etc.)
Results and Impact I am a founding member of the Grants and Awards Working Group (WG-GA). Based on my research experience in Japan and Singapore, I represent Asia-related MCAA fellows.

The Grants and Awards Working Group in MCAA recognises and supports its members in their research initiatives and provides financial support in the forms of Grants and Awards. Every year, this Working Group will focus on the shaping and development of the Grant and Award Programme to support selected activities and initiatives of MCAA members. The number of the initiatives to be supported each year will be dependent on the allocated budget.

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Year(s) Of Engagement Activity 2013
 
Description Lecture - Conscience and values in the response to infectious diseases - Thomas More Institute, London 
Form Of Engagement Activity A talk or presentation
Part Of Official Scheme? No
Geographic Reach International
Primary Audience Other academic audiences (collaborators, peers etc.)
Results and Impact -
Year(s) Of Engagement Activity 2011
URL http://thomasmoreinstitute.org.uk/papers/conscience-and-values-in-the-response-to-infectious-disease...
 
Description Lecture - How does science contribute to our understanding of life? Institute of St. John, London 
Form Of Engagement Activity A talk or presentation
Part Of Official Scheme? No
Geographic Reach International
Primary Audience Undergraduate students
Results and Impact -
Year(s) Of Engagement Activity 2013
 
Description Lecture on the AIDS epidemic for the charity Mothers to Mothers London 
Form Of Engagement Activity A talk or presentation
Part Of Official Scheme? No
Geographic Reach International
Primary Audience Public/other audiences
Results and Impact -
Year(s) Of Engagement Activity 2011
URL http://www.m2m.org
 
Description Lecture to Y6 children "Investigating microbes" at the Oratory RC Primary School, London. 
Form Of Engagement Activity A talk or presentation
Part Of Official Scheme? No
Geographic Reach Regional
Primary Audience Schools
Results and Impact Lecture to Y6 children "Investigating microbes" at the Oratory RC Primary School, London.

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Year(s) Of Engagement Activity 2013
 
Description Live comment on the origin of the AIDS epidemic on Arise News 
Form Of Engagement Activity A press release, press conference or response to a media enquiry/interview
Part Of Official Scheme? No
Geographic Reach International
Primary Audience Media (as a channel to the public)
Results and Impact Live comment on the origin of the AIDS epidemic on Arise News

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Year(s) Of Engagement Activity 2014
URL http://www.arise.tv/arise-news-show/africa-wrap-03-10-8501
 
Description Waldegrave Secondary School Visit 
Form Of Engagement Activity Participation in an open day or visit at my research institution
Part Of Official Scheme? No
Geographic Reach National
Primary Audience Schools
Results and Impact -
Year(s) Of Engagement Activity 2013