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Re-challenge of pigs following recovery from proliferative enteropathy

Collins, A.M., Love, R.J.
Veterinary microbiology 2007 v.120 no.3-4 pp. 381-386
swine, weanlings, polymerase chain reaction, disease transmission, Lawsonia intracellularis, oral administration, porcine proliferative enteritis, bacterial colonization, animal models, dose response, disease course, disease detection, seroconversion, disease control, microbial detection, immune response
An experimental challenge model was developed to demonstrate Lawsonia intracellularis colonization and reproduction of proliferative enteropathy (PE) in naïve weaner pigs. Groups of pigs were orally dosed with between 10¹⁰ and 10⁵ L. intracellularis extracted from haemorrhagic PE affected mucosa. Pigs were monitored for clinical signs and intestinal lesions of PE and evidence of bacterial colonization by serology and faecal polymerase chain reaction (PCR). One group of challenged pigs were necropsied after 21 days to confirm the reproduction of PE. L. intracellularis colonization and seroconversion was delayed in pigs dosed with lower numbers of L. intracellularis. When faecal shedding of L. intracellularis ceased to be detected in all of the challenged pigs, they were re-dosed orally with approximately 10¹⁰ L. intracellularis and monitored for evidence of re-colonization and clinical disease. This study demonstrated that pigs previously challenged with L. intracellularis were protected from re-colonization and clinical disease on subsequent exposure 10 weeks later, regardless of the initial dose of L. intracellularis.