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Coulibaly Lab research

CollaborationsStudent research projects | Publications

Insect viruses have a profound impact on human activities through the diseases they cause, their role in the control of invertebrate populations and major biotechnological applications.

Our research focuses on understanding the biology of some of these viruses to inform the design of new vaccines and biotechnological tools. To this end, we integrate complementary structural biology approaches to generate detailed models of infectious particles and virus-induced assemblies that facilitate infection. Specifically, we aim to elucidate these complex structures in their near native state using innovative methodologies such as cryo-electron microscopy, in vivo crystallisation and X-ray serial microcrystallography.

Current projects

1. Structural analysis of insect viruses relevant to biotechnology and human health

2. MicroCubes: natural crystals as antigen carriers and universal platform for vaccine discovery

3. Understanding the assembly of large DNA viruses

4. Exploring the virosphere with cryo-electron microscopy

Visit Associate Professor Coulibaly's Monash research profile to see a full listing of current projects.

Research activities

Microcrystals of insect viruses

Despite significant theoretical and experimental advances, protein crystallization remains the main bottleneck in most structure determination pipelines. Over the last decade, the study of proteins that crystallize as part of the normal viral infectious cycle has provided new insights into this process that may ultimately contribute to alleviating this bottleneck.

The first X-ray structures of in vivo crystals were elucidated from viral polyhedra produced by cypoviruses [1] and baculoviruses [2] using microcrystals directly purified from infected insects. The function of polyhedra is to package up to hundreds of viral particles constituting the main infectious form of the virus and allowing the virus to persist for years in the environment like bacterial spores.

By contrast with these viruses, insect poxviruses produce two types of microcrystals in infected cells: virus-containing spheroids representing their main infectious form; and spindles, bipyramidal crystals of the viral fusolin protein, that contribute to the oral virulence of these viruses (cf. Figure). Using serial microcrystallography, we have  determined the structure of viral spindles [3] allowing a comparative analysis of three completely different architectures of in vivo crystals. These various molecular organisations suggest common strategies of self-assembly that hint to features facilitating crystallization and more particularly in vivo crystallization, which has been proposed as a potential new route for structure determination. We are developing approaches to produce and analyse crystals in cellulo with improved efficiency [4].

  1. Coulibaly F., Chiu E., Ikeda K., Gutmann   S., Haebel P.W., Schulze-Briese C., Mori H. and Metcalf, P. (2007). The   Molecular Organization of Cypovirus Polyhedra. Nature 446:97-101.

  2. Coulibaly F.*, Chiu E., Ikeda K., Gutmann S., Haebel P.W., Schulze-Briese C., Mori   H. and Metcalf, P.* (2009). The atomic structure of baculovirus polyhedra   reveals the independent emergence of infectious crystals in DNA and RNA   viruses. Proc Natl Acad Sci USA. 106:22205-10

  3. Chiu E, Hijnen M, Bunker RD, Boudes M,   Rajendran C, Aizel K, Oliéric V, Schulze-Briese C, Mitsuhashi W, Young V,   Ward VK, Bergoin M, Metcalf P, Coulibaly F. (2015) Structural basis for the enhancement of   virulence by viral spindles and their in vivo crystallization. Proc   Natl Acad Sci USA. 112 (13):3973-78

  4. Boudes M, Garriga D, Fryga A, Caradoc-Davies T, Coulibaly   F (2016) A pipeline for structure   determination of in vivo-grown crystals using in cellulo diffraction. Acta. Cryst. D72:576-585.

MicroCubes: natural crystals as antigen carriers and universal platform for vaccine discovery

Polyhedra are ultra-stable protein crystals that form a protective capsule around the infectious particles of common insect viruses. We engineer these crystals to incorporate complex antigens of interest in place of the virus particles as a vaccine platform for infectious diseases.

MicroCubes with eGFP as cargo

Polyhedra are protein crystals formed in vivo by insect viruses. Their role in the viral cycle is to embed virus particles and protect them in the environment, which means that polyhedra have remarkable robustness and packaging ability. We are interested in exploiting these features to engineer microparticles as a new platform for vaccination (www.monash.edu.au/assets/pdf/industry/microcube-info.pdf)

Understanding the assembly of large DNA viruses

How large and giant viruses assemble is not understood at a molecular level and may relate to their origin, which remains controversial. We investigate the assembly of poxvirus membrane to provide insights into this process and reveal new targets to combat viruses in the family that cause human diseases.

Caption: Poxvirus artistic representation of poxvirus IV-like particles based on X-ray crystallography and cryo-EM data.

Contrary to most enveloped viruses, poxviruses do not acquire their internal membrane by budding through cellular compartments. Instead they mature from crescent-shaped precursors whose origin and structure remains controversial. This process results in the formation of non-infectious spherical particles called immature virions or IV.

To investigate the mechanisms underlying this essential maturation step, we focus on a scaffolding protein called D13 in vaccinia virus, the prototype poxvirus. This protein forms a honeycomb scaffold on the surface of IV. Its central role in poxvirus assembly is highlighted by the fact that point mutations of D13 block morphogenesis before the formation of IV. Also the antibiotic rifampicin induces a similar arrest in vaccinia virus morphogenesis that is overcome by point mutations in D13.

Our structure-function studies of the formation of crescents and IV aim at understanding how poxvirus acquire and remodel their membrane, a fundamental process possibly shared by a large group of DNA viruses [1]. This research may also provide new targets for the development of antivirals specifically blocking the assembly of poxviruses [2].

  1. Hyun JK, Accurso C, Hijnen M, Schult P, Pettikiriarachchi A, Mitra   AK* and Coulibaly F*(2011). Membrane   remodeling by the double-barrel scaffolding protein of poxvirus. PLoS   Pathogens 7:e1002239.

  2. Garriga D,    Heady S, Accurso C,   Gunzburg M, Scanlon M, Coulibaly F (2018)   Structural basis for the inhibition of poxvirus assembly by the antibiotic   rifampicin. Proc Natl Acad Sci USA 115(33):8424–8429.

Exploring the virosphere with cryo-electron microscopy

Using an integrated structural biology approach based on cryo-electron microscopy and X-ray crystallography, we investigate the structure of viruses that have biotechnological and biomedical applications – such as phage therapy and vaccine - but for which critical molecular details are missing.

Techniques/expertise

  • Structural biology including X-ray crystallography and cryo-electron microscopy
  • Molecular Virology
  • Protein engineering
  • Vaccinology

Disease models

  • Viral diseases (HCV, HIV, influenza virus, poxviruses)
  • Malaria
  • Antimicrobial resistance (bacteriophage therapy)

Collaborations

We collaborate with many scientists and research organisations around the world. Some of our more significant national and international collaborators are listed below. Click on the map to see the details for each of these collaborators (dive into specific publications and outputs by clicking on the dots).

1. Prof. Trevor Lithgow, Monash University – Bacteriophage biology
2. Prof. Martin Scanlon, MIPS - Understanding and blocking the assembly of poxviruses
3. Dr. Jacomine Krijnse-Locker, Pasteur Institute (France) - Poxvirus assembly
4. Prof Heidi Drummer and Andy Poumbourios, Burnet Institute – HCV and HIV entry
5. Dr. Daniel Watterson, UQ – Pathogenic insect viruses
6. Prof. James Beeson and Dr Rose French, Burnet Institute - MicroCube vaccine technology
7. Prof. Jade Forwood, CSU - Circovirus assembly and evolution


Student research projects

The Coulibaly Lab offers a variety of Honours, Masters and PhD projects for students interested in joining our group. There are also a number of short term research opportunities available.

Please visit Supervisor Connect to explore the projects currently available in our Lab.