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Streptococcus suis is an important worldwide endemic swine pathogen, which causes meningitis, septicemia, arthritis, and endocarditis in weaned piglets between 4 and 10 weeks of age. Mortality rates can be as high as 20 % in some farms and the total cost of S. suis infection in pigs is estimated to more than EUR 250 million annually in Europe alone. As of today, there are no approved vaccines available against S. suis infection in pigs.
Protection against a broad spectrum of S. Suis strains
The experimental infection model involved the intravenous administration of a high dose of the virulent serotype 9 strain of S. suis (ST16) to induce systemic disease. The study showed that vaccination of pregnant sows was safe and provided statistically significant protection (total clinical score; p = 0,017) to piglets compared with piglets from an unvaccinated control group. The vaccine has previously conferred statistically significant protection to piglets against a virulent serotype 2 strain (ST1). The vaccine is administered to pregnant sows by intramuscular injection making it simple and cost-effective for pig farmers to use.
The subunit vaccine, which is based on Intervacc’s platform using recombinant fusion proteins, is designed to give protection against a wide range of S. suis strain types, using conserved, immunogenic, and virulence-associated proteins from S. suis.
S. suis serotype 2 strains are the most common global cause of severe disease in piglets. Serotype 9 is currently less prevalent than serotype 2 but is increasingly responsible for severe pig diseases in Europe. Protection from a vaccine against multiple S. suis serotypes has been sought after by the pig farming industry for many years. Intervacc is the first company to show that a vaccine protected piglets against the highly virulent serotypes 2 (ST1) and 9 (ST16). This is a major breakthrough since the strains used in the studies are not closely related and the vaccine was only administered to pregnant sows with subsequent transfer of maternal immunity to their piglets.
Reduced need for antibiotics and improved profitability for pig farmers
It is estimated that S. suis accounts for one-third of the total antibiotic usage in weaner pigs. A safe and efficacious vaccine against S. suis would reduce the need for antibiotics and the global threat from antimicrobial resistance, play a significant role in improving animal welfare, and improve the profitability of the pig farming industry.
A game-changing breakthrough
“The significant levels of protection provided to piglets against these virulent and severe disease-causing types of S. suis, after the vaccination of pregnant sows, is novel and very encouraging” says Dr. Andrew Waller, Chief Scientific Officer at Intervacc. “These data underline the strengths of our technology platform, which generate broad immune responses that target multiple virulence pathways required by complex bacterial pathogens”.
“This breakthrough is a game-changer in the fight to protect pigs from the severe disease-causing strains of S. suis and merit its further development into a commercial vaccine” says Carl-Johan Dalsgaard CEO of Intervacc.
Intervacc will continue advancing the vaccine and prepare for GMP manufacturing and pivotal clinical studies.
March 19, 2026 - Intervacc
