Characterisation of the immunological response to Lawsonia intracellularis and improvement of diagnostic tools
Item statusRestricted Access
Embargo end date31/07/2022
Campillo Poveda, Marta
Lawsonia intracellularis (L. intracellularis) is an obligate intracellular bacterium associated with enteric disease in pigs. Clinical signs include weight loss, diarrhoea and, in some cases, sudden death. The hallmark pathology is the thickening of the intestinal mucosa due to increased epithelial cell replication known as proliferative enteropathy. The diagnosis tools currently available for L. intracellularis often have limited sensitivity and differentiation of vaccine from field isolates is not possible. Furthermore, the immune response to L. intracellularis is not well defined and detection of the infection, especially in the early stages, is still a significant challenge. In this thesis, I have investigated a number of potential new antigens that will help to gain a better understanding of the L. intracellularis infection adaptive immune responses, as well as to guide improvements in current diagnostic tools. Tools that can differentiate between vaccine and field isolates would be extremely helpful to veterinarians, and in this thesis, we have developed a ‘differentiating infected from vaccinated animals’ (DIVA) qPCR based on the genomic differences found between the wild type strains, the Enterisol® Ileitis (Boehringer Ingelheim Vetmedica) vaccine strain and the vaccine parental strain. My research has also investigated the pathogenesis of L. intracellularis in different environments by using in vitro culture under different conditions and in vivo in two pig trials. To summarise, as we have gained this knowledge about the bacterium and its pathogenicity, we have increased the power of diagnosis to guide appropriate interventions of L. intracellularis infection, a disease that threatens the sustainability of the pig industry worldwide through impacts on the welfare of animals and the economics of production.