Molecular basis of La Crosse virus entry and neuropathogenesis
La Crosse virus (LACV), a member of the Bunyaviridae family, is a mosquito-borne pathogen that is leading cause of paediatric encephalitis in North America. Most cases of LACV infection are asymptomatic. However, the virus can cause severe disease when it infects the central nervous system: approximately 1% of LACV neuroinvasive disease cases are fatal, and it causes neurological sequelae including epilepsy and cognitive abnormalities in a further 6-15% of cases. LACV neuroinvasive disease is most common in children under the age of 16.
LACV is an enveloped virus with a tripartite, negative-sense RNA genome consisting of small (S), medium (M), and large (L) segments. The M segment encodes the glycoproteins Gn and Gc that are present on the surface of virus particles. These glycoproteins recognise receptors on the surface of suitable host cells and catalyse the membrane fusion that allows entry of the viral genome into the host cell, the essential first step of the infection cycle. The cell surface receptor(s) of LACV have not been characterised, limiting our understanding of which cells can be infected and of why children but not adults suffer severe LACV neuroinvasive disease.
We have performed an unbiased protein-based screen to identify human cell surface proteins that bind the surface glycoproteins of LACV. We identified that LACV binds to receptors of the Notch signalling pathway. This result is highly significant because Notch receptors are regulators of neuronal development, helping determine whether neural progenitor cells differentiate into neurons or glial cells. Biochemical and biophysical experiments using purified components have confirmed that LACV binds these receptors with high affinity, and we have a high-confidence structural prediction of the interaction between LACV and these cell surface receptors.
This project will define the molecular interactions between LACV and its cell surface receptors at atomic resolution, using a combination of structural biology, biochemical and biophysical techniques. We will exploit this information to generate structurally informed mutations that disrupt these interactions, allowing us to test the functional consequences of Notch receptor binding for LACV infection and neuropathogenesis. Students undertaking this project will gain experience of biochemistry, biophysics, structural biology and molecular virology, with the opportunity to perform virus infection experiments in a high-containment environment. They will also advance our knowledge of an important paediatric disease, potentially identifying new strategies to prevent LACV infection or minimise the subsequent neurological sequelae.