ApprochesÉtant donné l’étendue de nos questions de recherche, nous employons une grande diversité de techniques de biologie moléculaire, de biochimie, de biologie cellulaire et d’ l’immunologie pour étudier la pathogénie du VIH. Les personnes formées dans notre laboratoire acquièrent systématiquement des connaissances spécialisées dans chacun de ces domaines. En plus d’utiliser des lignées cellulaires humaines comme modèle, nous avons recours à des cellules immunitaires primaires humaines, du matériel biologique prélevé sur des personnes infectées par le VIH et des méthodes de disruption génique pour étudier la fonction de gènes spécifiques in vivo. Nos études bénéficient des infrastructures offertes par l’Institut de recherches cliniques de Montréal (IRCM), y compris ceux mis en place pour la virologie (laboratoires de bioconfinement de niveau 2 et 3), l’immunologie, la génomique, la protéomique, la cytométrie en flux, la microscopie, l’histologie, la transgénèse et la disruption génique.
Areas of investigationAcquired Immune deficiency Syndrome (AIDS) is a slow degenerative disease of the immune and nervous systems resulting from a chronic and persistent infection by the human immunodeficiency virus type-1 (HIV-1). Despite considerable progress made in our comprehension of HIV-1 infection, we still do not completely understand how the virus causes disease and how it persists in infected individuals in presence of a vigorous immune response and highly suppressive antiretroviral regimens. Several lines of evidence suggest that HIV-1 persists not only by populating sanctuary sites throughout the body but also by employing multiple genetic strategies that together contribute to lifelong infection and efficient transmission. As all retroviruses, HIV-1 irreversibly integrates its proviral DNA into the host cell genome - a process that ensures its maintenance throughout the lifetime of the infected cell. In addition, given the high sequence diversification that occurs during replication, HIV-1 has the ability to escape or tolerate adaptive immune responses as well as developing resistance to antiretroviral drugs. Importantly, one of the defining features of primate immunodeficiency viruses is that they encode a number of accessory proteins, Vif, Vpr/Vpx, Vpu and Nef, which are not commonly found in other retroviruses; overall, the function of these viral proteins is to interact with fundamental host cell processes to modify the local environment within infected cells to ensure persistence, replication, dissemination and transmission. In at least two instances, Vif and Vpu, the primary activity of these accessory proteins appears to be evasion from various forms of cell-mediated antiviral resistance that may be part of the innate immunity to retrovirus. Vif inhibits the antiviral activity of innate factors, APOBEC-3F and -3G, which disable HIV-1 infectivity by inducing G-to-A mutations in the nascent DNA formed during reverse transcription. Vpu induces the degradation of the primary viral CD4 receptor and counteracts the antiviral activity of a newly identified interferon (IFN)-regulated host restriction factor, Tetherin/BST2/CD317, to promote efficient release of infectious virions. Interestingly, both Vif and Vpu interact with modular cullin ring ubiquitin (Ub) E3 ligases to exert their functions.
My laboratory focuses on the interactions of HIV-1 with host target immune cells, which govern viral replication, persistence and transmission. Our current studies are aimed at understanding the functional role of the Vpu and Vpr accessory proteins in HIV-1 infection and pathogenesis and at elucidating in molecular and cellular terms their mechanism of action.
ApproachesDue to the broad scope of experimental questions, we employ a wide range of molecular, biochemical, cell biological and immunological techniques to study HIV pathogenesis. Individuals completing training in the laboratory routinely acquire expertise in all of these areas. Increasingly, we are utilizing human primary immune cells, biological material isolated from HIV-infected individuals and gene disruption approaches to study the function of specific genes in vivo. Our studies often take advantage of the outstanding core services offered at the Institut de recherches Cliniques de Montréal (IRCM) including cores in Virology (Level 2 and 3 Biocontainment laboratories), Immunology, Genomics, Proteomics, Flow Cytometry, Microscopy, Histology, Transgenesis and Gene Disruption.