Resposta imune celular e humoral em suínos imunizados com a vacina inativada Porcilis® Ileitis e desafiados com Lawsonia intracellularis

Abstract

Lawsonia intracellularis is an obligatory intracellular bacterium that infects enterocytes causing the disease known as Proliferative Enteropathy (PE). Protective immune response against L. intracellularis in pigs are commonly associated with the production of IgG and IgA antibodies in the serum and intestinal mucosa, respectively. The objective of the present study was to evaluate the performance and protection of pigs vaccinated with Porcilis® Ileitis. Seventy-two 3-week-old pigs from a herd with no history of PE were used. Animals were divided in four different groups: Vaccinated/Challenged (VAC/CHAL), Vaccinated (VAC), Challenged (CHAL) and Control (CONT). All animals were weighed during the experiment and feed intake data was recorded for performance evaluation. Serum samples were collected from all animals and examined by IPMA to detect specific serum IgG and also ileal washes for the detection of IgA against L. intracellularis. Whole blood samples were collected from animals in the 4 groups and examined by the ELISPOT technique to detect IFN-γ producing cells that respond specifically to L. intracellularis antigens. Clinical and anatomopathological evaluations were also performed. From day 28 to day 49, for ADG and FC, a significant reduction was observed betweem the CHAL and the other groups. The detection of anti-L intracellularis antibodies produced after vaccination could be detected on day 14 post-vaccination (pv). The peak of detection of IgG anti-L intracellularis antibodies in serum occurred on day 28pv. On day 49pv, IgG specific for L. intracellularis was detected in all animals in the VAC and VAC/CHAL groups and in four animals in DES group. For the induction of specific cellular immune response, significant difference was detected between the VAC/DES and CONT groups on day 49 pv. For the results of the anatomic-pathological evaluation, a significant difference was detected between the DES group and the others, only for the macroscopic evaluation. Based on the results of Imunoperoxidase Monolayer Cell Assay and ELISPOT, the Porcilis® Ileitis vaccine proved to be efficient in inducing specific humoral and cellular responses.