Exploring trained immunity to complement vaccination against Streptococcus suis in swine

Area of Science:

• Veterinary Immunology
• Swine Infectious Diseases
• Innate Immune Memory

Background:

• Streptococcus suis causes significant swine diseases like septicaemia and meningitis.
• Control is challenging due to serotype diversity, genetic variation, and maternal antibody interference.
• Antibiotic resistance in S. suis strains presents further difficulties.

Purpose of the Study:

• To assess if a mycobacterial immunomodulator (dpB) combined with an S. suis vaccine enhances pig protection.
• To evaluate the efficacy of live and inactivated dpB formulations.
• To investigate the impact on immune responses and clinical outcomes.

Main Methods:

• Thirty-two pigs were divided into four groups: vaccine only, vaccine + live dpB, vaccine + inactivated dpB, and controls.
• Animals received two immunizations followed by challenge with S. suis serotype 2.
• Immune responses were measured via cytokine levels, ex vivo blood stimulation, and phagocytosis assays.

Main Results:

• Pigs receiving vaccine and inactivated dpB showed reduced bacterial loads and lung lesions.
• This group exhibited milder clinical symptoms and less bacterial dissemination post-challenge.
• Elevated pre-challenge cytokine levels were observed in the inactivated dpB group.

Conclusions:

• Inactivated dpB combined with S. suis vaccination offers a potential complementary strategy for improved swine protection.
• This approach may enhance host defense mechanisms against S. suis infections.
• Further research is warranted to understand mechanisms and integrate into disease prevention programs.