Lawsonia intracellularis is an important pathogen of pigs in which it causes an enteric diseases called, amongst other terms, proliferative enteropathy or ileitis.
The disease manifests in several forms all of which are characterised by the presence of L. intracellularis within intestinal epithelial cells and a resultant increased replication of infected epithelial crypts (hyperplasia). The main effect of infection is altered performance and growth of pigs although some infections may be severe enough to result in fatalities. Control of infection can be achieved through antibiotic usage although a novel vaccine has been available for several years.
L. intracellularis is a highly unusual bacterium not closely related to other pathogens. Its closest relatives are mostly found in the environment and some may be occasionally found as intestinal residents or, very rarely, as causes of septic infections. L. intracellularis differs significantly in other ways from related bacteria – it is obligately intracellular and has a small genome size typical of bacteria adopting this lifestyle.
In common with many pathogens, L. intracellularis possesses a specialised Type 3 secretion system (T3SS) [Alberdi et al., Veterinary Microbiology 139 (3-4), 298-303] as well as multiple proteins characteristic of “autotransporter” or type 5 secretion system (T5SS) family. Typically, these systems play important roles in interactions between bacteria and their hosts and the T5SS forms the focus for an on-going project funded under the BBSRC CEDFAS initiative.
We have carried out analysis of the available genome sequence (link to NBIS website pages with accession numbers NC_008011, NC_008014, NC_008013, NC_008012) for T3SS “effector” proteins. Multiple putative effectors have been identified at several chromosomal locations and functional assessment of a subset of these is underway.
Proteomics and immunoproteomics investigations have identified major immunogenic proteins of L. intracellularis and further appraisal of these is underway.
|Relevant Lawsonia Publications.pdf||17.15 KB|
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