Coulson Laboratory
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Include: Research interests | Major research projects | Laboratory staff | Recent Publications
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Research interests
A major focus of this group has been the role played by integrins in rotavirus-cell attachment and entry and this has lead us to the discovery of rotavirus-integrin interactions. We also are analysing the role of rotavirus infection in progression to type I diabetes, following our initial reports of the possible association of rotavirus with diabetes. Other areas of strong interest include cell signalling induced by rotavirus infection, sialic acids as rotavirus receptors, and identification of compounds that inhibit rotavirus interaction with receptors.
Major research projects
Studies on rotavirus-cell binding and entry, cell signalling induced by rotavirus, and rotavirus modulation of type 1 diabetes development
Rotaviruses are the major cause of severe acute diarrhoeal illness of infants and children. They are responsible for one-third of all hospitalizations for diarrhoea worldwide, and for an estimated 873,000 deaths/year, mostly in developing countries. Prevention of disease due to rotavirus is a major aim of paediatric medical research.
The quadrivalent live RRV-reassortant rotavirus vaccine showed 60-80% protection against severe diarrhoea in the USA and was the first rotavirus vaccine to have been licensed for use in humans. However, this vaccine was shown to be associated with a significant increase in incidence of intussusception in vaccinees, and was withdrawn in October, 1999. This vaccine also showed a lower efficacy in developing countries. Two new live attenuated vaccines are now being licensed worldwide. The use of oral rehydration therapy has led to decreased mortality rates, but no preventative therapies are available as yet.
A major interest of my group is the interaction of rotavirus with cellular receptors, as an understanding of rotavirus cell entry is likely to lead to development of improved vaccines and therapies. Rotavirus infection of cells appears to be a multi-step process involving virus binding, protease-dependent cleavage of the viral spike protein VP4 and pH-independent entry. The attachment of many rotaviruses to cells involves cellular sialic acids. Rotaviruses appear to enter cells in a novel mechanism involving direct penetration of the cell membrane.
Our most recent results show that multiple members of the integrin family of heterodimeric adhesion molecules are important for rotavirus cell entry. We found that the rotavirus spike protein VP4 contains the alpha2beta1 integrin ligand sequence DGE. We showed that the DG residues are essential for binding of this protein, expressed as a GST fusion protein, to expressed alpha2 integrin subunit I domain, and the I domain is necessary for virus binding to alpha2beta1 integrin. In addition, we showed that the major outer capsid glycoprotein VP7 contains the alpha4beta1 ligand sequence LDV and the alphaxbeta2 ligand sequence in a region showing significant sequence homology to the snake venom disintegrin family of integrin counter-ligands. In our experiments, peptides containing these ligand sequences and monoclonal antibodies directed to these integrins blocked rotavirus infection of cells in a dose-dependent fashion. We also showed that cells permissive to rotavirus express the integrins alpha2beta1 and alphaxbeta2. Most clincially significant human rotaviruses use integrins alpha2beta1, alphaxbeta2 and alphavbeta3 during cell attachment or entry. Currently, we are studying the roles of integrins in rotavirus interactions with immune cells, and are mapping the I domain amino acids necessary for virus binding. We have concluded that these integrins can act as receptors or co-entry molecules for many rotaviruses.
We are collaborators with structural chemists in a program to determine the molecular basis of rotavirus VP4 binding to cell surface carbohydrates, and design sialylmimetics as rotavirus inhibitors. Compounds identified in this program (and those from elsewhere to integrins) that are potentially inhibitory to rotavirus cell binding and infection are being evaluated for their potential as anti-viral agents.
We are also analysing the signalling pathways elicited in host cells by rotavirus binding and infection, and the nature of the cell death induced by rotavirus.
Another focus of our research is rotavirus modulation of type 1 diabetes. In collaboration with researchers at WEHI, we originally showed that rotavirus infection appears to trigger autoimmune responses to pancreatic antigens in children at high risk of developing type I diabetes. We have now shown that mouse, pig and monkey islets are susceptible to rotavirus infection, and are studying the effect of rotavirus infection in mouse models of type 1 diabetes development. Most recently, we determined that rotavirus infection delays diabetes onset in mice infected as infants or young adults.
Laboratory staff
Head and Senior Research Fellow (NHMRC)
Dr Barbara Coulson PhD
Email: barbarac@unimelb.edu.au
Dr Gavan Holloway, Research Officer
Ms Fiona Fleming, Research Assistant
Mr Peter Halasz, PhD Student
Ms Thanhmai Truong, BSc Hons Student
Recent Publications
List of Publications prior to 2007
- Kraschnefski M, Bugarcic A, Fleming F, Yu X, von Itzstein M, Coulson B, Blanchard H. Effects on sialic acid recognition of amino acid mutations in the carbohydrate-binding cleft of the rotavirus spike protein. Glycobiology 2009; 19 194-200.
- Holloway G, Truong T, Coulson B. Rotavirus antagonizes cellular antiviral responses by inhibiting the nuclear accumulation of STAT1, STAT2 and NF-{kappa}B. Journal of Virology 2009; 83: 4942-4951.
- Haselhorst T, Fleming F, Dyason J, Hartnell R, Yu X, Holloway G, Santegoets K, Kiefel M, Blanchard H, von Itzstein M, Coulson B. Sialic acid dependence in rotavirus host cell invasion. Nature Chemical Biology 2009; 5: 91-93.
- Yu X, Guillon A, Szyczew A, Kiefel M, Coulson B, von Itzstein M, Blanchard H. Crystallization and preliminary X-ray diffraction analysis of the carbohydrate-recognizing domain (VP8*) of bovine rotavirus strain NCDV. Acta Crystallographica Section F - Structural Biology and Crystallization Communications 2008; 64: 509-511.
- Graham K, Sanders NT, Tan Y, Allison J, Kay T, Coulson B. Rotavirus infection accelerates type 1 diabetes in mice with established insulitis. Journal of Virology 2008; 82: 6139-6149.
- Halasz P, Holloway G, Turner S, Coulson BS. Rotavirus replication in intestinal cells differentially regulates integrin expression by a phosphatidylinositol 3-kinase-dependent pathway resulting in increased cell adhesion and virus yield. J Virol 2008; 82: 148-160.
- Blanchard H, Yu X, Coulson BS, von Itzstein M. Insight into host-cell carbohydrate-recognition by human and porcine rotavirus from atomic structures of the virion spike associated carbohydrate-binding domain (VP8*). J Mol Biol 2007; 367: 1215-1226.
- Graham KL, Tan Y, O’Donnell JA, Sanders N, Carrington EM, Allison J, Coulson BS. Rotavirus infection of infant and young adult nonobese diabetic mice involves extraintestinal spread and delays diabetes onset. J Virol 2007; 81: 6446-6458.
- Fleming FE, Graham KL, Takada Y, Coulson BS. Rotavirus-neutralizing antibodies inhibit virus binding to integrins α2β1 and α4β1. Arch Virol 2007; 152: 1087-1101.
- Haselhorst T, Blanchard H, Frank M, Kraschnefski M, Kiefel MJ, Fleming FE, Holloway G, Coulson BS, von Itzstein M. STD NMR spectroscopy and molecular modeling investigation of the binding of N-acetylneuraminic acid derivatives to rhesus rotavirus VP8* core. Glycobiology 2007; 17: 68-81.
Note: Pre-2002 Publications can be viewed via links on Barbara Coulson's homepage.