Exploring a new paradigm for enveloped virus entry that identifies a new broad-range anti-viral target.

To infect a cell, viruses must deliver their genomes into the cell interior, and often this is via transit through the endocytic network. To escape the endosome and begin replication, viruses mediate fusion of viral and cellular envelopes using specialized spike proteins that respond to the changing biochemical environment of maturing endocytic vesicles. These biochemical conditions act like triggers to switch the fusion spikes from inactive to active conformations, and the aim of this project is to identify these triggers and determine how they work.
Bunyaviruses comprise the largest family of RNA viruses and represent an emerging threat to livestock and human health. We showed bunyaviruses require the activity of specific cellular potassium (K+) channels to cause infection. These channels serve to maintain [K+] within endosomes, and we established that [K+] is a newly defined biochemical trigger required for bunyavirus fusion, and thus infection.
Our data using cryo-EM show that K+ mediates conformational changes in the envelope spikes of a model bunyavirus (Hazara virus; HAZV) and promotes interactions with membranes. This represents the first visualization of monovalent metal ion dependant fusion, which may represent a conserved mechanism for bunyaviruses and beyond.
Furthermore, we have shown the K+ channels responsible can be blocked using clinically-available compounds. Thus, these channels are druggable targets for blockade of virus infection and disease.
Based on this exciting platform, we propose a multidisciplinary work plan that will define the mechanism that underpins the K+ requirement. We will then establish whether K+ channels represent a pan-viral therapeutic target to prevent infection by these serious pathogens
Objectives and approaches
Aim 1: Determine the biochemical requirements for infectivity, spike conformational changes and membrane interaction. Our data shows exposure to K+ acts to accelerate Bunyavirus infectivity and induces conformational changes in envelope spikes, and interactions with cellular membranes. The student will first determine whether any of the other cellular ions present within endosomes (Na+, Cl-, Ca2+ and H+) also induce the same changes in infectivity and spike properties.
Aim 2: High-resolution structural analysis of HAZV Gn/Gc spikes. Fusion spikes from several different Bunyaviruses will be studied by two complementary approaches: cryo-EM and crystallography. Cryo-EM will produce structures of the spikes within virions, and crystallography will generate high resolution domain structures. The University of Leeds (UoL) has recently invested ~£15M in new EM infrastructure, making it competitive with the best structural virology centres in the world.
Aim 3. Structure-function analysis using Bunyavirus reverse genetics systems. The high-resolution structures of Bunyavirus spikes will identify critical residues instrumental in conformational changes and/or fusogenic activities. To validate the function of these critical residues, we will use a HAZV reverse genetics systems to allow generation of infectious mutants at these selected sites.
Aim 4. Assess whether other segmented negative stranded RNA viruses require K+ as a biochemical trigger for fusion. Our results suggest that the dependence on [K+] for viral entry may extend to other negative stranded RNA viruses outside of the Bunyavirus group. We will test this hypothesis using pharmacological treatment of infected cells with K+ channel blockers, and then further examine the changes induced by K+ on their fusion spikes by cryo-EM.
Training environment
Supervisors are experts in molecular virology, virus-host interactions and structural biology. Techniques to be employed include reverse genetics, X-ray crystallography, cryo-electron microscopy and antiviral screening.
What we offer
The successful applicant will join the Faculty of Biological Sciences Post-Graduate Research Program at UoL with over 100 talented and motivated post graduate students passionate about research.
Applicant Requirements
Applicants should hold or expect a first/upper second-class degree or equivalent in a relevant subject with appropriate research experience and/or a Masters degree in a relevant subject. Knowledge of at least one of the following techniques is required (practical experience would be an advantage): virology and cell culture; electron microscopy imaging and data processing; X-ray crystallography.

Relevant publications
Hover S, Foster B, Fontana J, Kohl A, Goldstein S, Barr JN, Mankouri J. 2018. PLoS Pathogens doi:10.1371/journal.ppat.1006845.
Hover S, Foster B, Barr JN, Mankouri J. J Gen Virol. 2017, 98(3):345-351.
Hover S, King B, Hall B, Loundras EA, Taqi H, Daly J, Dallas M, Peers C, Schnettler E, McKimmie C, Kohl A, Barr JN, Mankouri J. J Biol Chem. 2016, 291(7):3411-22.