Lethal Virus Infection in Haploid Stem Cells

Outbreaks of emerging infectious diseases continue to threaten human and animal health in Europe and around the world. The arthropod-borne Rift Valley fever virus (RVFV) and Crimean Congo Haemorrhagic fever virus (CCHFV) are among the most prominent bunyaviruses, provoking symptoms like hepatitis, encephalitis, and even hemorrhagic fever and death in humans. While RVFV is predicted to have high potential for invading Europe, CCHFV is already present in south-eastern European states. Despite the growing importance of bunyaviruses as emerging pathogens, comparatively little is known about the molecular events and requirements during intracellular virus replication, and there is no specific therapy. To develop new antivirals and/or prevention strategies, we therefore need to characterize the pathogenesis and the molecular mechanism of infection both in vitro and in vivo. Organisms with a single copy of their genome, i.e., a haploid genome, provide a fundament for genetic analyses where any recessive mutation of essential genes will show a phenotype due to the absence of a second gene copy. Haploid embryonic stem cells carry the promise to revolutionize functional genetics and allow rapid, near whole genome-wide mutational forward genetics and reverse genetics analysis in defined cell types. By using the power of genome-wide, repairable, mutagenesis strategies, we will establish RVFV and CCHFV infection models in haploid ES cells in order to characterize essential cellular genes and pathways for virus infection. Furthermore, by using reverse genetic system for these pathogens, we will establish a platform to further identify and validate candidate factors for these lethal viruses. Our initiative aims to build on existing and entirely new cutting-edge expertise in Europe and to bring together leading scientists to work towards solving the key problems concerning emerging and often lethal viral diseases that are not tractable by individual groups.

As one consequence of climate change, microenvironments have changed in Europe that now permit viruses to enter Europe that we as a population have not been exposed to for centuries. It is therefore paramount to utilize cutting edge technologies to unlock fundamental mechanism of such virus pathologies. We have put together an international multidisciplinary consortium to address these critical issues, with a special focus on Bunyaviruses such as Rift Valley fever virus (RVFV) and Crimean Congo Haemorrhagic fever virus (CCHFV). While RVFV is predicted to have high potential for invading Europe, CCHFV is already present in south- eastern Europe. Despite the growing importance of Bunyaviruses as emerging pathogens, comparatively little is known about the molecular events and requirements during intracellular virus replication, and there is no specific therapy. The ESCential grant has allowed us to establish a European network combining knowledge in virology, genome engineering and advanced cell engineering. The experimental set-ups and critical host factor we have already identified for these viruses demonstrate the power of our platform to identify essential host genes for virus infections.