ABSTRACT
This chapter reviewed the immunostimulatory property of probiotics taking around the time of vaccination as vaccine adjuvants. Lactobacillus acidophilus NCFM™(LA) can enhance immunogenicity and protection of the AttHRV vaccine in Gn pigs. Probiotic LA and L. rhamnosus GG (LGG) at the appropriate dose are effective both in reducing rotavirus diarrhea as well as enhancing immunogenicity of the AttHRV vaccine. However, the dosage of probiotics influences their adjuvanticity. LA and LGG regulated rotavirus vaccine-induced immune responses in a dose-dependent manner. Low dose LA significantly enhanced effector T cell responses and down-regulated regulatory T cell responses whereas high dose LA had the opposite effects in Gn pigs. Intermediate dose LA significantly enhanced rotavirus-specific ASC and memory B cell responses induced by the AttHRV vaccine. Thus, the same probiotic strain used at different doses can either increase or reduce mucosal and systemic immune responses induced by vaccines. These findings have significant implications in the use of probiotic lactobacilli as immunostimulatory versus immunoregulatory agents. Optimal dosage of probiotics needs to be determined for the appropriate purposes. Although data from studies of Gn pigs may not be generalized directly to humans, Gn pig model provides a good starting point for identification of the optimal dosage of a probiotic adjuvant.
