Proliferative enteropathy: a global enteric disease of pigs caused byLawsonia intracellularis

Abstract

Proliferative enteropathy (PE; ileitis) is a common intestinal disease affecting susceptible pigs raised under various management systems around the world. Major developments in the understanding of PE and its causative agent, Lawsonia intracellularis, have occurred that have led to advances in the detection of this disease and methods to control and prevent it. Diagnostic tools that have improved overall detection and early onset of PE in pigs include various serological and molecular-based assays. Histological tests such as immunohistochemistry continue to be the gold standard in confirming Lawsonia-specific lesions in pigs post mortem. Despite extreme difficulties in isolating L. intracellularis, innovations in the cultivation and the development of pure culture challenge models, have opened doors to better characterization of the pathogenesis of PE through in vivo and in vitro L. intracellularis-host interactions. Advancements in molecular research such as the genetic sequencing of the entire Lawsonia genome have provided ways to identify various immunogens, metabolic pathways and methods for understanding the epidemiology of this organism. AbstractProliferative enteropathy (PE; ileitis) is a common intestinal disease affecting susceptible pigs raised under various management systems around the world. Major developments in the understanding of PE and its causative agent, Lawsonia intracellularis, have occurred that have led to advances in the detection of this disease and methods to control and prevent it. Diagnostic tools that have improved overall detection and early onset of PE in pigs include various serological and molecular-based assays. Histological tests such as immunohistochemistry continue to be the gold standard in confirming Lawsonia-specific lesions in pigs post mortem. Despite extreme difficulties in isolating L. intracellularis, innovations in the cultivation and the development of pure culture challenge models, have opened doors to better characterization of the pathogenesis of PE through in vivo and in vitro L. intracellularis-host interactions. Advancements in molecular research such as the genetic sequencing of the entire Lawsonia genome have provided ways to identify various immunogens, metabolic pathways and methods for understanding the epidemiology of this organism. The determinations of immunological responsiveness in pigs to virulent and attenuated isolates of L. intracellularis and identification of various immunogens have led to progress in vaccine development.

Lawsonia intracellularisContains a Gene Encoding a Functional Rickettsia-Like ATP/ADP Translocase for Host Exploitation

“…Proliferative enteropathy is characterized by a progressive proliferation of immature intestinal epithelial cells (enterocytes) following infection with L. intracellularis. The disease, which can persist for several weeks, leads to anorexia, diarrhea, reduced growth of infected animals, and decreased reproductive performance (27,34,46). Although proliferative enteropathy is considered one of the most economically important diseases in the swine industry worldwide, causing hundreds of millions of U.S. dollars in extra costs annually (27,29,36), data on the molecular mechanisms important for the pathogenicity and interaction of L. intracellularis with its host cells are surprisingly scarce.…”

“…L. intracellularis enters the host cell via induced phagocytosis; the phagosome is quickly degraded, and Lawsonia resides directly in the cytoplasm (27). L. intracellularis is an important veterinary pathogen causing proliferative enteropathy (ileitis) in many mammals but mostly in pigs (27,37,46). Proliferative enteropathy is characterized by a progressive proliferation of immature intestinal epithelial cells (enterocytes) following infection with L. intracellularis.…”

“…Proliferative enteropathy is characterized by a progressive proliferation of immature intestinal epithelial cells (enterocytes) following infection with L. intracellularis. The disease, which can persist for several weeks, leads to anorexia, diarrhea, reduced growth of infected animals, and decreased reproductive performance (27,34,46). …”

“…L. intracellularis is a gram-negative, microaerophilic, obligate intracellular bacterium belonging to the Deltaproteobacteria. L. intracellularis enters the host cell via induced phagocytosis; the phagosome is quickly degraded, and Lawsonia resides directly in the cytoplasm (27). L. intracellularis is an important veterinary pathogen causing proliferative enteropathy (ileitis) in many mammals but mostly in pigs (27,37,46).…”

A Novel Lawsonia intracellularis Autotransporter Protein Is a Prominent Antigen

“…Current diagnostic tools are not without their drawbacks: PCR amplification of bacterial DNA from the feces of infected animals is routinely employed, but detection is limited to when bacteria are excreted (19,39), and in situ detection of the bacterium within the intestines of infected animals can only be achieved postmortem (28). Serodiagnosis is considered to be a reliable and convenient indicator of exposure to the bacterium, particularly when evaluating the immune status of herds, (7,21).…”