Understanding the impact of Lawsonia intracellularis infection and vaccination on gut health

Lawsonia intracellularis is an important, ubiquitous pig pathogen causing a clinical syndrome known as porcine proliferative enteropathy (PPE), also known as ileitis which affects growing pigs and breeding animals. Besides the clinical impact on pigs and the economic consequences for pig production ileitis has relevance for public health and food safety as it is commonly treated with antibiotics. On one side, there is increasing pressure to reduce the use of antibiotics in food animals; on the other side, pigs need to be treated for animal welfare reasons. In this context, measures to prevent disease and reduce the use of antibiotics in pigs gain importance. Vaccination is seen as one of the most effective measures to reduce the need for antibiotics.

Since 2006 an oral, attenuated live vaccine against Lawsonia intracellularis is available in Europe. In recent years the use of this vaccine has increased, and the benefit of vaccination has been demonstrated extensively not only on pig health but also on reducing antimicrobial usage. Recent research suggests that Lawsonia intracellularis infection causes a temporary depletion of mucin, specifically mucin (MUC2) secreted from goblet cells, in Lawsonia intracellularis infected pigs that is correlated with increased levels of intracellular bacteria in crypt cells. This reduction in MUC2 levels may compromise the effectiveness of the mucus barrier and provide access for Lawsonia intracellularis and other pathogens. This is in line with data from other research groups indicating that infection with Lawsonia intracellularis increases the susceptibility of pigs to subsequent Salmonella spp. infection.

Objective 1. Characterization of the Enterosol Ileitis Lawsonia intracellularis vaccine strain (Boehringer Ingelheim) by genomic sequencing. Obtained information will be used for the development of diagnostic tools to differentiate pigs vaccinated with this vaccine strain from pigs naturally infected Lawsonia intracellularis. These tools will serve to monitor vaccinations complaints and to investigate Lawsonia intracellularis outbreaks in vaccinated herds.
Objective 2. Characterization of Lawsonia intracellularis infection and impact of Lawsonia intracellularis vaccination on infection at the cellular level including characterization of goblet cells and selected cytokines)
Objective 3. Impact of Lawsonia intracellularis infection on subsequent Salmonella enterica serovar Typhimurium challenge and protective effect of vaccination