Vaccination of pigs with attenuated Lawsonia intracellularis induced acute phase protein responses and primed cell-mediated immunity without reduction in bacterial shedding after challenge

Abstract

Although vaccinated and non-vaccinated pigs shed L. intracellularis at similar levels after challenge, a lower number of intestinal L. intracellularis was observed in the vaccinated pigs at post mortem inspection. This might be due to the observed faster CMI responses upon challenge in vaccinated pigs. Complete protection against infection without L. intracellularis shedding, however, was only seen after a previous infection resulting in IFN-γ production predominantly by CD8(+) and CD4(+) CD8(+) cells. Improved protective vaccines against L. intracellularis should therefore target stimulation of these T cell subsets.

Systemic cytokine response in pigs infected orally with a <i>Lawsonia intracellularis</i> isolate of South Korean origin

“…The response of cells to cytokines can be markedly affected by the “context”, and the systemic cytokine response in vivo is more valid for immunology than for any other type of research. Although several papers on mucosal, systemic, or primed cell-mediated immune responses to L. intracellularis have recently been published [ 1 , 16 , 17 , 21 ], most immunological researches on L. intracellularis have focused mainly on IFN-γ. Here we focused on in vivo research on cytokine involvement in porcine PE caused by L. intracellularis infection using a Korean isolate.…”

“…Among various cytokines, interferon-γ (IFN-γ) has been reported to play a significant role in limiting intracellular infection and increasing cellular proliferation associated with L. intracellularis and so far most immunological researches on L. intracellularis infection have focused mainly on IFN-γ [ 2 , 3 , 20 , 22 ]. The relevance of IFN-γ in L. intracellularis infection has been assessed mainly using IFN-γ receptor knockout mice [ 2 , 22 ], normal pigs [ 3 , 16 , 17 , 20 , 21 ], and horses [ 18 ].…”

“…Certainly, IFN-γ is one of the most important immunological molecules because IFN-γ is produced in large amounts and is crucial for the control of infectious diseases. Although several papers on mucosal, systemic, or primed cell-mediated immune responses to L. intracellularis have recently been published [ 1 , 16 , 17 , 21 ], the levels of various circulating inflammatory cytokines, including IFN-γ, in animals infected with L. intracellularis is still an area of considerable interest for understanding immunity against PE. In addition, there has been no information on cytokine response in animals infected with any L. intracellularis isolate of South Korean origin or Asian origin.…”

A Cell Proliferation and Inflammatory Signature is Induced by Lawsonia intracellularis Infection in Swine

“…These include the pathways of leukocyte extravasation signaling, dendritic cell maturation and acute phase response signaling. Increased levels of acute phase proteins have previously been found in pigs infected with L. intracellularis (52). This gives some insight into the mucosal immune response to infection which is known to be protective and suggests that antigen presentation with dendritic cells and the presence of leukocytes are an important part of this process.…”

Potent O-antigen-deficient (rough) mutants of Salmonella Typhimurium secreting Lawsonia intracellularis antigens enhance immunogenicity and provide single-immunization protection against proliferative enteropathy and salmonellosis in a murine model

“…An L. intracellularis modified-live vaccine (Enterisol ® Ileitis, Boehringer Ingelheim) is currently available and shows efficacy in reducing the severity of clinical symptoms in infected pigs. However, although currently available live attenuated LI vaccines have been shown to reduce clinical disease and to increase weight gain, however, these vaccines fail to induce complete protection against the LI challenge [ 2 ]. This live attenuated vaccine can be reactogenic, creating safety concerns.…”