Research Projects
Targeting Deubiquitylases as Therapeutic Strategies Against Viral Infections

Programme(s) to which this project applies:

☒ MPhil/PhD ☑ MRes[Med] ☒ URIS
About the Project

Objective and Significance:

Influenza virus is responsible not only for annual epidemics, but also for frequent outbreaks of pathogenic avian flu strains that have become a serious public health issue worldwide. The ubiquitylation machinery is frequently exploited by a number of pathogens either to masquerade as host proteins or to inhibit immune signaling cascades. We have employed a chemoenzymatic strategy to identify deubiquitylating enzymes (DUBs) that are specifically expressed upon influenza or dengue infections and are currently investigating the role of these DUBs. Our ongoing studies involve characterization and pharmacological intervention of these DUBs in order to attenuate virus infection. Preliminary data in macrophages and dendritic cells support the hypothesis that viruses takes advantage of DUBs to suppress signaling pathways such as RIG-I and inflammasome activation that require ubiquitin modification for recruitment of downstream effectors. We also propose to test small molecules that target these DUBs both in vitro and in vivo.

Research Plan and Methodology:

One of our research goals is to determine how ubiquitin and ubiquitin like modifiers are utilized by the host innate immune system and their modulation during viral infections. Within this context, we are investigating the role of deubiquitylating enzymes (DUB) that are expressed during influenza infection and their effect on the innate immune response. Our preliminary data indicate that upon influenza A infection in human lung epithelial cells (A549) as well as bone marrow derived macrophages in culture, the extent of ubiquitylated material recovered from whole cell lysates is dramatically reduced. We hypothesize that this is a consequence of either one or both of the following reasons: (i) upregulation of deubiquitylating enzymes (DUBs) by influenza virus that de-ubiquitylates host factors to enable a productive virus infection (ii) degradation of antiviral host restriction factors through the ubiquitin proteasome pathway to enable a productive influenza virus infection. In support of the first hypothesis we have identified DUBs, expressed during influenza infection, which function to block the inflammasome signaling pathway as well as the RIG-I pathway and result in compromise of the host innate immune response. We anticipate that by targeting this pathway using a combination of chemoenzymatic and pharmacological methods, we will be able to restore a more robust innate immune response and restrict virus replication. Targeting specific enzymes of the ubiquitylation machinery is an emerging therapeutic strategy. We propose to test two specific small molecule inhibitors to these DUBs that are available and have shown considerable promise as drugs in phase I and II clinical trials. Questions that we are specifically focused on addressing are as follows: Are certain DUBs specifically induced during influenza infection? Our preliminary results support the conclusion that specific DUBs are induced upon H1N1 infection. Using a version of ubiquitin (Ub) modified at its C-terminus with vinyl methyl ester (Ub-VME) and a combination of large-scale immunoprecipitation and proteomic analyses by mass spectroscopy, we have successfully identified DUBs that are expressed during H1N1 infection. What is the purpose of DUBs expressed during viral infections? Do they provide an advantage to virus replication? Are there differences between DUBs expressed by different strains of influenza virus, specifically between the seasonal human influenza H1N1 and the pathogenic avian influenza H5N1 and H7N9? We hypothesize that the DUB expression profiles for seasonal H1N1 and the pathogenic avian viruses would be different and their identity would provide insights into what host factors allow avian flu to become transmissible in humans. Given our success with the seasonal influenza, we aim to use the same strategy to identify and compare DUBs expression profiles with avian influenza.

About the Supervisor

Prof R Bruzzone, School of Public Health


Next Step?

For more information or to express interest for this project, please email the supervisor or the specified contact point in the project description.  Interested candidates are advised to enclose with your email:

  1. your CV,
  2. a brief description of your research interest and experience, and
  3. two reference letters (not required for HKUMed UG students seeking MRes[Med]/URIS projects).

Information on the research programme, funding support and admission documentations could be referenced online at the Research Postgraduate Admissions website. General admission enquiries should be directed to

HKUMed MBBS students interested in the Master of Research in Medicine (MRes[Med]) programme may visit the programme website for more information.  

HKUMed UG students interested in the Undergraduate Research Internship Scheme (URIS) may visit the scheme’s website for more information.