Investigation of the immunostimulant effect of inactivated Cutibacterium granulosum on foot-and-mouth disease vaccine

This study aimed to evaluate the potential immunostimulant effects of inactivated Cutibacterium granulosum on the immune system and its contribution to the immune response when administered in combination with an inactivated foot-and-mouth disease (FMD) vaccine. Foot-and-mouth disease is a highly contagious, acute, and zoonotic infection affecting cloven-hoofed animals and poses a significant threat to animal health worldwide and in our country. In the study, seventy-five 7-month-old New Zealand rabbits (2–2.5 kg) were randomly divided into five groups: control group, C. granulosum group, FMD vaccine group, C. granulosum + FMD vaccine group, and a group receiving the FMD vaccine 20 days after C. granulosum administration. Vaccinations were performed on days 1 and 20. Blood samples were collected on days 0, 20, 30, 45, 60, and 90, while spleen samples were collected on days 30, 60, and 90. Total antibody levels and leukocyte counts were determined from serum samples, and TNF-α, IL-1β, IL-2, IFN-γ, IL-8, and IL-12 levels were measured by ELISA. Gene expression levels of IFN-γ, TNF-α, and IL-1β from spleen samples were assessed using PCR. The results demonstrated that the administration of Cutibacterium granulosum either in combination with or prior to the FMD vaccine significantly enhanced the immune response in rabbits. Analysis of cytokine levels, leukocyte counts, and antibody responses revealed that both combination groups showed a significant increase in both cellular and humoral immunity.