Development and application of a novel system for investigation of equine herpesvirus infections and immune responses utilizing viral pseudotyping

Equine herpesviruses (EHV) are ubiquitous respiratory pathogens of horses worldwide, leading to significant welfare issues and economic losses. EHV-1 can cause neurological disease, paralysis and mortality in adults, foetal abortion and death of newborn foals. Unfortunately some animals are asymptomatic disease carriers, a problem exacerbated by typical herpesvirus lifetime infection and reactivation. The few vaccines available mainly provide protection against respiratory disease, so rapid diagnosis and quarantine is vital. Detection is usually via PCR during active replication. Serology permits a way of identifying infected horses via antibody presence, but current methods lack sensitivity and specificity. However, our equine influenza (EI) studies showed pseudotyped virus (PV) assays to be exquisitely sensitive for low level antibody detection compared with other methods. A recent paper described the first pseudotyping of a DNA virus (herpesvirus simplex), unusually using multiple surface glycoproteins, enabling target cell transduction and entry. The complex multi-protein entry mechanism has yet to be elucidated for EHV, but PVs provide a perfect model to test individual glycoprotein contributions to infection in isolation.

Objectives:
1) Generation of the first EHV pseudotyped virus particles bearing precise combinations of viral surface glycoproteins (employing lentivirus and/or rhabdovirus vectors).
2) Identification of surface glycoproteins required for EHV tropism for different equine cells (e.g. epithelial, dermal, CNS, mononuclear blood cells).
3) Development of a pseudotype-based assay for detection of neutralising antibodies in naturally infected horses for diagnostics and for vaccine evaluation (i.e. identification of immunodominant glycoproteins, measurement of magnitude and duration of immunity)

This project is a joint initiative between Dr Simon Scott (Viral Pseudotype Unit, Medway School of Pharmacy, University of Kent, UK) and Drs Romain Paillot and Stéphane Pronost (LABÉO/ University of Caen, Normandy, France), building on a prior collaboration. The study will involve research being conducted in both the Kent and Normandy, exploiting expertise, reagents (PV technology, equine cell models, unique sera) and in-house facilities at both institutes. The Viral Pseudotype Unit was established in 2011 to focus on basic and translational research with pseudotyped viruses. LABÉO is one of the largest French veterinary diagnostic and research laboratories linked with the University of Caen (EA7450 BIOTARGEN), with the research platform dedicated to equine health. The project is due to commence in September 2018..