Relationship between Ileal symbiont intracellularis and porcine proliferative enteritis

Abstract

The relationship between Ileal symbiont (IS) intracellularis, formerly known as a Campylobacter-like organism, and porcine proliferative enteritis (PE) was studied by use of pigs with experimentally transmitted PE. Twenty one pigs were experimentally inoculated with homogenized ileal mucosa from a pig that died with PE, and 7 were maintained as uninoculated controls. Fecal samples were collected, and pigs were necropsied weekly postinoculation. Light microscopy and electron microscopy were used to examine tissues for lesions of PE and infectious agents. DNA was extracted from the fecal samples and assayed for the presence of sequences specific for IS intracellularis by dot blot hybridization and polymerase chain reaction amplification. IS intracellularis was detected by the polymerase chain reaction in the feces of 20 of 21 inoculated pigs but not in the feces of uninoculated pigs. Seven inoculated pigs but no uninoculated pigs were detected shedding IS intracellularis by dot blot hybridization. Shedding was detected 1 to 5 weeks after inoculation, and clinical signs were seen in the second to fifth weeks after inoculation. Few pigs without lesions of PE were found to shed IS intracellularis. There was a highly significant association between the presence of IS intracellularis in feces or tissue and the presence of microscopic proliferative lesions and between the severity of the lesions of PE and the percentage of IS intracellularis-infected intestinal crypts. Pigs that ceased shedding IS intracellularis were significantly less likely to have proliferative lesions. These and previous reports are consistent with the hypothesis that IS intracellularis is a necessary causative agent of PE.

Comparison of a commercial ELISA with an indirect fluorescent antibody test to detect antibodies toLawsonia intracellularisin experimentally challenged pigs

“…Experimental challenge studies have demonstrated that serological results correlate well with shedding of L. intracellularis and clinical and histological evidence of PE 5,12–14 . Good correlations between serology and the duration of positive PCR results were also shown in this study; however, the predominantly subclinical population used in this study did not show strong correlations between serology and clinical scores.…”

Questionnaire survey of proliferative enteropathy on British pig farms

“…Nucleus herds belonging to major breeding companies experienced a high rate of infection with the disease. The infection of pigs with L intracellularis can occur over a wide age range; pigs nearly three months old have become infected by an oral challenge (Jones and others 1993b). The infection can persist in individual pigs for at least 10 weeks, with large numbers of L intracellularis being readily detectable in faeces during the same period (Smith and McOrist 1997).…”

A novel inactivated vaccine against Lawsonia intracellularis induces rapid induction of humoral immunity, reduction of bacterial shedding and provides robust gut barrier function

“…L. intracellularis also infects pigs sub-clinically, without clear clinical signs but still resulting in reduced growth performance. Its worldwide distribution and high prevalence have been recognized since the initial characterization of this pathogen in the early 1990s and L. intracellularis is reported to affect 57–100% of herds, globally [1] , [2] , [3] .…”