Abstract Streptococcus suis is a gram-positive opportunistic bacterium that colonizes respiratory and enteric epithelial tissues and is a major causative agent of invasive infections in pigs, leading to significant morbidity and mortality. A novel dairy bioactive, FXP™, is hypothesized to improve nursery pig performance due to its high concentration of immunoglobulins, dairy-derived lipids, and proteins which have demonstrated anti-pathogenic properties. The aim of the current experiment was to determine the efficacy of FXP™ in mitigating the infectivity of Strep. suis using a porcine epithelial cell culture model. Strep. suis (serotype 2), derived from porcine brain and tonsil tissues, was isolated from nursery pigs exhibiting clinical signs of disease. A preliminary study comparing the classical human bronchial epithelial cell model (HBE-135) with porcine epithelial cells (IPEC-J2) confirmed similar infectivity profiles. Treatment groups consisted of: 1.) Control (no pathogen, no FXP™), 2.) Strep. suis only, and 3.) Strep. suis + 0.50% FXP™. Prior to the experiment, Strep. suis cultures were grown overnight in Brain Heart Infusion (BHI) broth, and IPEC-J2 cells were cultured to confluence in trans well inserts using Dulbecco’s Modified Eagle Medium. Cells were pre-incubated with FXP™ for 1 hour, followed by a 1-hour exposure to Strep. suis at a multiplicity of infection of 50:1. Cytotoxicity, measured by lactate dehydrogenase release, remained below 20% across all treatments. After the 2-hour experiment, adherent and translocated Strep. suis were plated on BHI agar for enumeration (6 replicates per treatment). Cellular integrity was assessed by measuring transepithelial electrical resistance (TEER) (4 replicates per treatment). Co-incubation with FXP™ significantly reduced Strep. suis adhesion to and translocation through IPEC-J2 cells by 46% and 95%, respectively (P ≤ 0.02) compared to Strep suis only. Additionally, Strep. suis exposure tended to reduce TEER compared to the no pathogen control, an effect that was partially mitigated by FXP™ (P = 0.08). These results indicate that FXP™, a novel dairy bioactive technology, possesses anti-pathogenic properties against Strep. suis and can partially preserve porcine epithelial cell integrity during infection.
Horn et al. (2026) studied this question.