Today, we are sharing a recent publication from Dr. Vannucci lab in the Veterinary Diagnostic Laboratory at the University of Minnesota. This project evaluated the pig’s response to a co-infection with Lawsonia intracellularis and Brachyspira hyodysenteriae after receiving an ileitis vaccine. The full manuscript is available in open access on the journal website.

Methods

• 80 pigs, 21 days of age
• Five groups were created:
  • V-CO: LI-vaccinated and co-infected with LI + Bhyo,
  • P-CO: placebo and co-infected with LI + Bhyo,
  • V-LI: LI-vaccinated and infected with LI,
  • P-LI: placebo and infected with LI,
  • and NC: negative control, placebo, and non-challenged
• Vaccinated pigs received the Porcilis ileitis IM
• Pigs were challenged with LI 22 days after vaccination and with B.hyo 30 days after vaccination
• Fecal scores were collected every 2 to 3 days and fecal swabs were taken on D27, D31, D34, D38, D41 and 43.
• Serum was collected at D21, D29, D36, and D43.
• Between 2 and 6 pigs were necropsied for each group at D21, D29, D36, and D43.

Results

• Fecal scores were numerically higher for the P-CO and V-CO groups.
• P-CO had lower Ct-values for LI shedding in the P-CO group compared to V-LI and P-LI at several time points.
• No difference in B.hyo shedding was noted.
• V-LI had no gross intestinal lesions and one out of six V-CO animals had gross lesions on the colon, typically caused by Bhyo.
• Vaccinated pigs showed anti-LI serum IgG before the LI challenge. Their IgG levels was also higher and quicker after vaccination compared to the placebo groups.

Abstract

Vaccination is a tool to control Lawsonia intracellularis (LI) in pigs. However, pigs may have co-infections that worsen clinical signs and lesions. The aim of this study was to characterize systemic and gut-mediated humoral and cell-mediated immune (CMI) responses in pigs vaccinated with a killed intramuscular LI vaccine and to analyze the impact of co-infection with Brachyspira hyodysenteriae (Bhyo) on the immune response. The study included eighty pigs and five study groups: V-CO (LI-vaccinated and co-infected with LI + Bhyo, n = 21), P-CO (placebo and co-infected with LI + Bhyo, n = 18), V-LI (LI-vaccinated and infected with LI, n = 21), P-LI (placebo and infected with LI, n = 12), and NC (negative control, placebo and non-challenged, n = 8). Parameters analyzed: fecal score and pathogen shedding), gross intestinal lesions, LI intestinal colonization (IHC), serum IgG, LI-specific IFN-γ production (ELISPOT), and immune cell subsets (flow cytometry) in blood, mesenteric lymph nodes, Peyer’s patches, and intestinal epithelium. LI vaccination significantly reduced LI fecal shedding, intestinal colonization, and macroscopic lesions—even under Bhyo co-infection. Vaccinated pigs had earlier and stronger serum IgG and IFN-γ responses. B cells seem to play an important role in the local immune response, and T regulatory cells apparently do not have a significant role in immunomodulation. This study contributes to a better understanding of LI immune response and can provide subtract for further research in the control of LI.