HEV in Pigs: Understanding Infection Dynamics and Deciphering Prevention Strategies. - OZ0516

Hepatitis E virus (HEV) is the causative agent of hepatitis E in humans. In Western countries hepatitis E was historically associated with travel related acquisition, however in the last 15 years, in the UK and across Europe a continuous increase in non-travel associated cases has been noted. There is substantial evidence of an association with pork/pork products and HEV zoonotic transmission. Several studies have also highlighted the risk of HEV zoonotic transmission via undercooked contaminated pork products. This has led to growing interest as to how HEV enters the pork food chain. To date, studies have mainly focused on surveillance and limited molecular characterisation, as the study of HEV was commonly restricted by the difficulty in isolating and culturing field strains, with viral genetic heterogeneity often limiting complete molecular characterisation. The UKZADI report Policy Options for Reducing the Risk of Hepatitis E in the Food Chain (2018) provided suggestions for managing HEV on farm and at slaughter/during pork processing. Subsequently at APHA techniques have been established to obtain HEV full genome sequences; the isolation and culture of field strains and an oral dose infection model to study HEV in pigs. These tools will enable further study on HEV dynamics from farm to fork and provide much needed data to inform mitigation strategies. The programme of research described in this application reflects upon the questions raised in the UKZADI report and takes subsequent scientific developments into account, also building on recent work conducted at APHA. Working with stakeholders across government, an updated time of slaughter assessment (i.e., abattoir survey) is intended to provide current HEV prevalence data at the point of entry in the food chain. Surveillance based farm studies have been reported in the literature, often using pooled samples to determine the presence or absence of HEV in farming systems. Complementarily, it is aimed here to work in collaboration with UK pig farming to compare different farming systems and selected groups pigs throughout their lifespan, understanding the impacts of farming systems and biosecurity upon the continuous transmission of HEV. In collaboration with academic partners, in vivo investigations into the pathogenesis of HEV and to investigate the use of vaccines, will inform strategies to control HEV on farm. In addition, it is intended to produce pork products (e.g., ham) from HEV experimentally infected pigs and investigate whether the virus remains viable. This leads to the final aim of this research programme: augmentation of the toolkit to study and control HEV in pigs. Whilst several technical difficulties such as the culture of HEV have been addressed, others, such as extraction from and preparation of food samples for virus isolation remain, thus an alternative approach to virus isolation to confirm viral viability will also be investigated.