Mechanism of action of an african swine fever virus virulence factor. THIS GRANT IS A SUPPLEMENTATION TO GRANT REF BB/E021239

Lead Research Organisation: The Pirbright Institute
Department Name: Div of Microbiology Pirbright

Abstract

Abstracts are not currently available in GtR for all funded research. This is normally because the abstract was not required at the time of proposal submission, but may be because it included sensitive information such as personal details.

Technical Summary

We will investigate the function of an African swine fever virus (ASFV)-encoded protein, DP71L which we have recently shown both inhibits activation of transcription from the interferon IFN-beta promoter and stimulates protein phosphatase 1 (PP1) activity in infected cells. Our data has shown that DP71L can inhibit both IRF-3- and NF-kB-dependent gene transcription, suggesting it may have a broader effect on host immunomodulatory gene transcription. The DP71L protein is expressed as either a long form localised mainly in the nucleolus or a short form localised mainly in the nucleus of cells. Deletion of the short form of the gene dramatically reduces virulence in pigs. We propose that DP71L acts as a regulatory subunit of PP1 to activate and target the enzyme to dephosphorylate specific substrates in the nucleus and suggest that this is the mechanism by which IFN induction is inhibited. We will map the domains in DP71L that are required to bind to and stimulate PP1 and to inhibit IFN. This will establish if these two activities are linked. We will also determine at which point DP71L blocks IFN induction and establish if this is linked to inhibition of NF-?B activation. We will also investigate if DP71L modulates transcription of other immunomodulatory genes. To determine if these activities of DP71L are linked to its role in virulence, we will replace the wild-type gene on the virus genome with mutant DP71L genes which do not have these functions. Virulence will be studied in pigs. We will also monitor the in vivo effect of DP71L expression on induction of IFN and activation of IFN-induced pathways as well as other predicted functions of DP71L. The results will improve our understanding of the IFN induction pathway as well as revealing novel functions for PP1 and how these may be targeted by viruses. In addition we will learn more about mechanisms of virus pathogenesis which will help in the rational design of attenuated virus vaccines. Joint with BB/E019781/1

Publications

10 25 50
 
Description The function of an African swine fever virus viruelnce factor, DP71L, was studied. We showed that DP71L recruits a cellular enzyme, protein phosphatase 1, to remove phosphate from the protein translation initiation factor eIF2alpha and thus prevents the global shut-off of protein synthesis in ASFV infected cells. The activation of host cell death pathways dependent on induction of ATF4 and CHOP are also prevented by DP71L. As a consequence virus replication is favoured since the virus replication cycle can be completed more efficiently. In cells infected with ASFV as expected phosphorylation of eIF2alpha and activation of ATF4 and CHOP was not detected. Surprisingly this was also observed in cells infected with ASFV deletion mutants lacking the DP71L gene. Therefore we conclude that ASFV has additional mechanisms to inhibit these pathways. The results were published in a paper in Journal of Virology (Zhange et al., JOURNAL OF VIROLOGY Volume: 84 Issue: 20 Pages: 10681-10689 DOI: 10.1128/JVI.01027-10 Published: OCT 2010).Preliminary evidence indicated that DP71L has additional functions for example in inhibiting transcriptional activation of the IFN beta gene.
Exploitation Route Deletion of the gene may be used to construct candidate attenuated vaccines
Sectors Agriculture, Food and Drink