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Research Abstracts Online
January - December 2011

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University of Minnesota Twin Cities
College of Veterinary Medicine
Department of Veterinary and Biomedical Sciences

PI: Connie J. Gebhart

Transcriptional Profiling of a Pathogenic and an Attenuated Homologous Lawsonia intracellularis Isolate During in Vitro Infection

Lawsonia intracellularis is the causative agent of proliferative enteropathy, an endemic disease in pigs and an emerging concern in horses. Spontaneous attenuated isolates obtained through multiple passages in cell culture do not induce disease. Conversely, bacterial isolates at low cell passage induce clinical and pathological changes. The identification of genes differentially expressed between a pathogenic and an attenuated homologous L. intracellularis isolate can help to elucidate virulence factor-encoding genes involved in this infection. This study used high-throughput sequencing technology to characterize the transcriptional profiling of a pathogenic and an attenuated isolate during in vitro infection. Bacterial RNA was harvested from infected piglet intestinal epithelial cells (IPEC-J2) five days post-infection (approaching peak of infection). A total of 319 protein-encoding genes were expressed in both pathogenic and attenuated isolates. These common genes between the two strains are involved in metabolic, biosynthetic and cell motility pathways, such as chemotaxis and flagellar assembly. Only 10 genes in the chromosome and one in the plasmid LIB (parA – ATPase involved in chromosome partitioning) were uniquely expressed by the attenuated strain. In contrast, 401 mapped genes were exclusive to the pathogenic strain. Genes involved in ATP-binding cassette transporter synthesis, two-component system and protein export pathways were responsible for this wider transcriptional landscape, which were distributed in the chromosome and three plasmids (LIA, LIB, LIC). In addition, only sequences from the pathogenic strain could be mapped against the plasmid LIA, which may play an important role in the course of infection. These researchers identified distinct genes and pathways between a pathogenic and an attenuated L. intracellularis strains. This information supports the project hypothesis and opens a new research field for studying target genes involved in the ecology, pathogenesis, and physiology of L. intracellularis.

Group Members

Molly Kelley, Graduate Student
Fabio Vannucci, Graduate Student