Associate Professor Jason Mackenzie BSc (Hons) Phd
|Academic Degrees||Contact Details|
1991: BSc (Hons), University of Otago, Dunedin, New Zealand
1996: PhD, University of Queensland
Tel: +61 3 9035 8376
Fax: +61 3 8347 1540
Room 4.18B, Department of Microbiology and Immunology
2013 - present: Senior Lecturer, Department of Microbiology and Immunology, University of Melbourne
2007 - 2013: Senior Lecturer, Department of Microbiology, La Trobe University, Melbourne
2002: Alexander von Humbolt Fellow, EMBL, Heidelberg, Germany
Our overall objectives are to investigate and unravel the replication mechanism of two positive-stranded RNA viruses (West Nile virus [a flavivirus] and Mouse Norovirus [a Norovirus]) that are highly pathogenic to humans and cause outbreaks of encephalitis and gastroenteritis. Our aims are to determine how and where these viruses replicate within infected cells and what host components/organelles are “used and abused” by the virus. We aim to correlate this abuse of host with the pathogenic outcomes associated with viral infection. In conjunction with these studies we are investigating how viruses can evade our immune system and in particular how viruses can bypass the antiviral activities of our first line of defence; the innate immune system.
In particular we investigate:
Role of Cellular Lipids during Flavivirus replication – Dr Benjamin Dickerman,
Dr Andrea Mikulasova (previous post-doc) and Ms Leah Gillespie
A 3D representation of the WNV replication complex
The intracellular replication of many (+)RNA viruses is associated with intracellular membranes. We have extensively characterised this intimate association during the replication of the flavivirus West Nile virus (WNV) and showed there is a dramatic re-organisation of membrane architecture during replication. In particular, redistribution of cellular lipids to replication sites that appears to favour WNV replication and survival. To extend these studies we have assessed in the global changes in lipid metabolism and are evaluating the contributions each of these lipids on WNV replication. More significantly we have identified a specific lipid binding domain in one of the WNV proteins and mutation of this domain severely restricts WNV infection. We aim to determine how lipids impact on membrane remodelling and how changes in lipid homeostasis affect cell metabolism, survival and immune competency.
Collaborators: Rob Parton (University of Queensland) and Gareth Griffiths (University of Oslo, Norway)
West Nile virus replication and cellular stress responses – Dr Rebecca Ambrose
WNV dramatically alters the intracellular environment of infected cells. Earlier studies from our lab have shown that viral protein expression and assembly all occur at the endoplasmic reticulum (ER), and that this organelle is also a source of membranes for the replication structures observed during infection. As a result, WNV places a significant amount of stress on the ER, thus we are interested in investigating the effect that WNV replication has on the ER stress response. Our studies have shown that WNV modulates signalling from the ER to benefit replication, activating pro-survival pathways whilst simultaneously inhibiting pro-apoptotic and translational arrest effectors. We have also demonstrated that by hijacking this signalling pathway, WNV can concurrently inhibit antiviral signalling, and that this is mediated by the hydrophobic viral proteins. We are currently investigating the cross-talk between ER stress and anti-viral signalling, as well as determining the exact effectors of ER stress vital for WNV replication.
Our current model of how WNV can manipulate and modulate cellular responses to promote survival.
Visualization and Formation West Nile virus Replication Complexes – Mr Turgut Aktepe (PhD Student)
During WNV replication, intracellular membrane structures are dramatically altered. Towards the end of the latent period, translation is observed in virally induced membrane structures called convoluted membranes (CM) and paracrystalline arrays (PC) and RNA synthesis is observed in vesicle packets (VP).These membrane structures are crucial for the efficient replication of flaviviruses and are linked to the exponential increase in virus production. However, previous visualization of these structures has been static at fixed time points. We aim to visualize the formation and proliferation of these virally induced membrane structures over real time using time-lapse epi-fluorescence. Recently, proteins localizing to the CM/PC and VP have been identified and we aim to tag these proteins, in frame, with a reporter protein to visualize WNV replication over real-time. We are also interested in determining host/viral protein interactions for membrane biogenesis. A number of host proteins are known to form cellular membrane structure. During infection, these cellular proteins can be recruited by viral proteins to aid in CM/PC and VP formation. Identifying and understanding these interactions can allow us to determine WNV replication and which components/organelles are used and abused during viral infection.
Autophagy and Norovirus replication – Ms Tanya O’Donnell (PhD student)
We are also interested in the role autophagy plays in MNV-1 replication. Autophagy is a cellular mechanism used to recycle proteins and degrade pathogens as a method of prolonging cell life. We have since discovered that MNV-1 infection induces autophagy but does not utilize the autophagosomal membranes to facilitate replication. Various techniques have been used in this project including; immunofluorescence, western blotting, qPCR, plaque assays and live cell imaging. Further analyses will examine the effects of autophagy inducing and inhibiting compounds on MNV-1 replication and what implications these results will reveal about how MNV-1 is able to manipulate cells.
Collaborators: Justine Mintern (University of Melbourne) and Skip Virgin (Washington University School of Medicine, USA)
Norovirus replication and innate immunity – Mr Ben Cotton (PhD Student)
Previous work has shown that innate immune response is vital to norovirus pathogenesis. Thus we aim to further examine the interaction between the virus and the host with particular focus on the signalling pathway components leading to IFN activation or more importantly subversion/inhibition by viral components. We have utilised cell lines deficient in several key Interferon pathway receptors/components to further elucidate their role in host response to infection. We have observed that MNV1 can subvert both intracellular recognition of virus replication and downstream signalling and activation of the immune response, mediated via type 1 interferon. We are currently investigating the precise mechanisms that mediate virus evasion, particularly the roles of the individual viral proteins.
Collaborators: Paul Hertzog, Brian Williams & Ashley Mansell (Monash Institute of Medical Research, Melbourne) Peter White (University of NSW, Sydney) and Skip Virgin (Washington University School of Medicine, USA)
Associate Professor Jason Mackenzie
Dr Rebecca Ambrose, Research Officer
Dr Benjamin Dickerman, Research Officer
Ms Leah Gillespie, Research Assistant
Mr Benoit Cotton, PhD student
Ms Tanya O’Donnell, PhD student
Mr Turgut Aktepe, PhD student
Mr Adam Lopez-Denman, PhD student
Ms Helen Pham, Honours student
- G. Haqshenas, J.M. Mackenzie, X. Dong and E.J. Gowans. The HCV p7 protein is localized in the endoplasmic reticulum when it is encoded by a replication competent genome. J Gen Virol 2007; 88: 134-142.
- S.R. Schaecher, J.M. Mackenzie and A. Pekosz. The ORF7b protein of SARS-CoV is expressed in virus-infected cells and incorporated into SARS-CoV particles. Journal of Virology 2007; 81: 718-731.
- J.M. Mackenzie, M.T. Kenney and E.G. Westaway. West Nile virus NS5 polymerase is a phosphoprotein localized at the cytoplasmic site of viral RNA synthesis. J Gen Virology 2007; 88: 1163-1168.
- H. Malet, M.-P. Egloff, B. Selisko, R.E. Butcher, P.J. Wright, M. Roberts, A. Gruez, G. Sulzenbacher, C. Vonrhein, G. Bricogne, J.M. Mackenzie, A.A. Khromykh, A.D. Davidson and B. Canard. Crystal Structure of the RNA polymerase domain of West Nile Virus NS5. Journal of Biological Chemistry 2007; 282: 10678-89.
- J.M. Mackenzie, A.A. Khromykh and R.G. Parton. Cholesterol manipulation by West Nile virus perturbs the cellular immune response. Cell Host & Microbe 2007; 2: 229-239.
- A. Hoenen, W. Liu, G. Kochs, A.A. Khromykh and J.M. Mackenzie. West Nile virus-induced cytoplasmic membrane structures provide partial protection against the interferon-induced antiviral MxA protein. J Gen Virology 2007; 88: 3013-3017.
- J.Y. Leung, G.P. Pijlman, N. Kondratieva, J.L. Hyde, J.M. Mackenzie and A.A. Khromykh. The role of non-structural protein NS2A in flavivirus assembly. Journal of Virology 2008; 82: 4731-4741.
- M.J. Snooks, P. Bhat, J.M. Mackenzie, N.A. Counihan, N. Vaughan and D.A. Anderson. Vectorial entry and release of hepatitis a virus in polarized human hepatocytes. Journal of Virology 2008; 82: 8733-8742.
- J.C. Martyn, A.J. Cardin, B.D. Wines, A. Cendron, S. Li, J.M. Mackenzie, M. Powell and E. J. Gowans Surface display of IgG Fc on baculovirus vectors enhances binding to antigen-presenting cells and cell lines expressing Fc receptors. Archives of Virology 2009; 154: 1129-1138.
- J.L. Hyde, S.V. Sosnovtsev, K.Y. Green, C. Wobus, H.W. Virgin and J.M. Mackenzie. Mouse norovirus replication is associated with virus-induced vesicle clusters originating from membranes derived from the secretory pathway. Journal of Virology 2009; 83: 9709-9719.
- J.L. Hyde, and J.M. Mackenzie. Subcellular localization of the MNV-1 ORF1 proteins and their role in the formation of the MNV-1 replication complex. Virology 2010; 406: 138-148.
- L.K. Gillespie, A. Hoenen, G. Morgan and J.M. Mackenzie. The Endoplasmic reticulum provides the membrane platform for biogenesis of the flavivirus replication complex. Journal of Virology; 84: 10438-10447.
- R.A. Bull1, J. Hyde, J.M. Mackenzie, G.S. Hansman, T. Oka, N. Takeda and P.A. White. Comparison of the replication properties of murine and human calicivirus RNA dependent RNA polymerases. Virus Genes 2011; 42: 16-27.
- R.L. Ambrose and J.M. Mackenzie. West Nile virus differentially modulates the unfolded protein response to facilitate replication and immune evasion. Journal of Virology 2011; 86: 2723-2732.
- R.L. Ambrose and J.M Mackenzie. A conserved peptide in West Nile Virus NS4A protein contributes to proteolytic processing and is essential for replication. Journal of Virology 2011; 85: 11274–11282.
- J.L. Hyde, L.K. Gillespie and J.M. Mackenzie. Mouse Norovirus-1 utilises the cytoskeleton network to establish localization of the replication complex proximal to the microtubule organizing centre. Journal of Virology 2012; 86: 4110-4122.
- S.-S. Wong, G. Haqshenasa, E.J Gowans and J.M. Mackenzie. The localization and oligomeric properties of the dengue virus M protein. FEBS Letters 2012; 586: 1032-1037.
- J.L. Hyde and J.M. Mackenzie. Pathogenesis and replication of norovirus: following the mouse tail? Microbiology Australia 2012; 33: 74-76.
- R.L. Ambrose and J.M. Mackenzie. ATF6 signaling is required for efficient West Nile virus replication by promoting cell survival and inhibition of innate immune responses. Journal of Virology 2013; 87: 2206-2214.