We initially identify new host-pathogen and host-host protein interactions using a proteomics approach. We then explore the significance of these novel interactions using a combined structural (e.g. X-ray crystallography, SAXS), biophysical (e.g. analytical ultracentrifugation) and functional approach (e.g in vitro assays, cell-based assays). Pathogens of interest include influenza, HIV, respiratory syncytial virus, Zika virus, dengue virus, West Nile virus and members of the Enterobacteriaceae (eg. Salmonella, Shigella).
Viral infection is a significant cause of global mortality and economic burden. Did you know the Spanish influenza outbreak of 1918 killed more than 40 million people? Or that hepatitis B is the most common infectious disease in the world, causing 600,000 deaths each year?
Host organisms detect and clear viral infection by coordinating between the innate and adaptive arms of immunity. The retinoic acid-inducible gene I (RIG-I)-like receptors (RLRs) are antiviral pattern recognition receptors that act as sentinels for viral RNA from pathogens of significance to human health such as influenza, hepatitis B, hepatitis C and respiratory syncytial virus.
Once activated these innate immune RLR receptors recruit downstream signalling proteins that lead to the induction of type I interferons (IFN) such as IFN-α and IFN-β. These type I IFNs activate JAK-STAT (Janus kinase/signal transducers and activators of transcription) signalling, leading to the induction of hundreds of genes that control the viral infection. We are interested in identifying new connections between proteins in the RLR signalling cascade and the functional relevance of the interactions. Our current focus is how E3 ligases posttranslational modify RLR signalling proteins with ubiquitin to modulate signalling.
The success of a pathogen is partly determined by how well it can utilise host cell proteins for replication and also evade the host innate immune response. Well-known RNA viruses like influenza A and hepatitis C implement immune evasion strategies. Unfortunately, these immune evasion mechanisms are often poorly understood and hampered by our limited understanding of how antiviral immunity is activated by innate immune receptors such RIG-I. We are interested in mechanistically understanding how microbial pathogens target host cell proteins within the RLR signalling cascade.
The correct subcellular localisation of host and microbial proteins is central to their function. We are interested in better understanding how host and microbial proteins use nuclear transport receptors to shuttle between the nucleus and cytoplasm. Agents that selectively alter the nuclear transport of host or microbial proteins have potential application as therapeutics for microbial pathogens of significance.
We use a combined approach to study our innate immune response to infection. Techniques used within the laboratory include molecular biology, recombinant protein expression, protein purification, X-ray crystallography, small angle X-ray scattering, analytical ultracentrifugation, biochemical assays, high-resolution imaging, gene knockdown/knockouts, luciferase assays, coimmunoprecipitation.
Acknowledgement of country
RMIT University acknowledges the people of the Woi wurrung and Boon wurrung language groups of the eastern Kulin Nation on whose unceded lands we conduct the business of the University. RMIT University respectfully acknowledges their Ancestors and Elders, past and present. RMIT also acknowledges the Traditional Custodians and their Ancestors of the lands and waters across Australia where we conduct our business. - Artwork created by Louisa Bloomer