Abstract
Hepatitis E virus (HEV) causes hepatitis E in humans and is present worldwide. The primary route of transmission is faecal-oral, which is dominant in developing countries where drinking water can be contaminated, and conditions possibly unsanitary. There are several genotypes (HEV1-8) of the virus, which are distributed across most continents. However, within the last 15 years there has been an increase in the number of autochthonous cases of hepatitis E (genotype 3) in countries within Europe, including the UK, and the United States of America. Despite there being a few transmission routes of HEV, there is evidence to suggest this rise in cases originated from pigs through the consumption of undercooked, contaminated pork products, such as pigs’ livers and pork sausages. This is due to HEV being endemic in the pig population and pigs being a reservoir host. As a result of this foodborne zoonosis, research has investigated the progression of HEV infection in the pig to determine how the virus is entering the pork food chain. Although many of these studies were successful in infecting pigs with HEV, they utilised alternative routes of inoculation such as intravenous, which do not represent the natural route of infection, i.e., faecal-oral. Consequently, these studies may produce different results to what is observed in the farm environment, such as faecal shedding, viraemia, and HEV detections in the muscle meat occurring earlier than expected.
This project employed a multi-faceted approach to gain a better understanding of HEV pathogenesis in the pig and overcome weaknesses in HEV research, such as the lack of an established oral inoculation model for HEV in pigs. A UK pig farm located in South-West England was explored to provide a recent dataset on the current HEV genotypes in circulation on one farm. This contributes to the topic as evidence suggests the increase in hepatitis E cases are suspected of originating from imported pork products, therefore providing data to demonstrate HEV stability in the UK pig population supports this notion. Cell culture systems were investigated to learn more about HEV replication in vitro and to propagate virus stocks for in vivo studies. Finally, an oral inoculation model was established to provide a natural route of infection and follow the course of HEV infection within the pig. This model can be used in future research to determine how HEV is entering the food chain.