Calicivirus
Calicivirus Research Group (Dr Ian Goodfellow, group leader)
For a full description please see our lab pages at:
WWW.CALICIVIRUS.CO.UK
Our research interests focus on the molecular mechanisms that positive stranded RNA viruses use to translate and replicate their genomes, with particular interest in members of the Caliciviridae family, primarily noroviruses. .
Often referred to as ‘winter-vomiting disease’, the human enteric caliciviruses (noroviruses and sapoviruses) are a major cause of gastroenteritis worldwide and frequently cause the closure of hospital wards in the UK. Noroviruses have been associated with up to 93% of non-bacterial GE and between 60-85% of all gastroenteritis outbreaks in the United States, Europe and Japan. The human caliciviruses, including the prototype Norwalk virus, do not replicate in tissue culture, hence we know very little with regards to the molecular mechanisms these viruses use for genome translation and replication. In contrast to the human caliciviruses, feline calicivirus (FCV), porcine enteric calicivirus (PEC) and murine norovirus (MNV) can be propagated in tissue culture. Our lab uses a variety of state of the art methods to examine the basic mechanisms of calicivirus translation and replication as well as aspects of pathogenesis. Two ongoing areas of research within the group include:
Analysis of calicivirus translation initiation
We have recently reported that caliciviruses use a novel protein-directed translation initiation mechanism that involves the binding of translation initiation factors to the virus encoded VPg protein that is covalently linked to the 5’ end of the viral RNA (Goodfellow et al. EMBO Reports 2005 and Chaudhry et al. JBC 2006). This mechanism has not seen in any other animal RNA virus, but shares some limited similarity with a mechanism proposed for members of the plant potyvirus family. We demonstrated that both the FCV and Lordsdale virus, a human norovirus (NV), VPg proteins interact directly with the eIF4E component of the eIF4F cap-binding complex. Translation of FCV VPg-linked mRNA was inhibited by the eIF4E inhibitor 4E-BP1, confirming a functional role for eIF4E and suggesting that the eIF4E-4G interaction is essential for FCV translation. Current work focuses on the analysis of the roles of other translation initiation factors in calicivirus translation using proteomics, as well as the identification of inhibitors of this novel translation mechanism as potential anti-viral therapeutics.
Molecular analysis of calicivirus replication
The replication of positive-stranded RNA viruses occurs on the surface of membranous vesicles in the cytoplasm of the infected cell. The formation of these replication complexes occurs via a complex network of protein-protein interactions between individual viral proteins, and also between viral and host cell proteins. Characterisation of interactions between viral proteins using the yeast two-hybrid system has allowed the formation of protein linkage maps for a number of viruses including poliovirus, potato virus A, pea seed-borne mosaic virus, infectious bursal disease virus, vaccinia virus and a number of others. Although not exhaustive, such linkage maps are informative, as they not only identify new interactions but also those that are amenable to fine detail mapping using yeast two-hybrid analysis. This can often allow the identification of the specific amino acids or exposed surfaces of proteins that are required for the interactions to occur, information that is useful for the design of small molecule inhibitors of such interactions. We have recently generated a protein-linkage map for FCV as a model member of the Caliciviridae family (Kaiser et. al. J. Gen. Virol. 2006). This has been followed up with a number of papers describing the identification of membrane bound components of the calicivirus replication complex (Bailey et al. J. Gen. Virol. 2010). We have also identified a number of conserved RNA structures in the calicivirus genome which play a role in virus replication (Simmonds et al. NAR 2008) and viral virulence (Bailey et al. J. Virol 2010). Current work focuses on the further characterisation of the interactions observed using two reverse genetics systems developed within the lab (Chaudhry et al J. Gen Virol 2007 and Yunus et al. J Virol Methods 2010), the generation of calicivirus replicons and the identification of RNA binding proteins that interact with the viral genome.
The overall aim of the ongoing work within the group is to gain a greater insight into the molecular mechanisms caliciviruses use for genome translation and replication. A better understanding of how these viruses interact with the host cell and how this interaction leads to genome replication will aid greatly in our ability to control the frequent outbreaks of these viruses.
Current funding is from the Wellcome Trust, European Union and MRC.
Further detailed information regarding the current members of the research group and ongoing research can be found within our research group pages available here:WWW.CALICIVIRUS.CO.UK
