Improving Vaccine Response through Probiotics and Micronutrient Supplementation: Evaluating the Role of TLR5 in Adult Female BALB/c Mice.

Background: The role of probiotics and micronutrients in improving immune system function and response to vaccination has been proven. Hence, this study aimed to investigate the effects of probiotics enriched with micronutrients on the immunogenicity of PastoCovac® vaccine.

Methods: The probiotic supplement BioBoost® and PastoCovac® vaccine, which contain six expressed receptor-binding domains (RBD) and conjugated with tetanus toxin, were administered concurrently. The safety and efficacy were assessed by determining Immunoglobulin G (IgG) antibody titers to RBD and cytokines, mRNA expression of Toll-like Receptors (TLRs) 5, and clinical symptoms.

Results: Results revealed that the administration of the probiotics enriched with micronutrients and vitamins for 14 days before the first vaccine dose, followed by continued supplementation for 14 days after the first dose, and in conjunction with the second vaccine dose, yielded the most significant elevation in interleukin 4 (IL-4), Tumor Necrosis Factor-alpha (TNF alpha), Interferon-gamma (IFN-gamma), and anti-SARS-CoV-2 RBD IgG levels within the supernatant samples collected from spleen cultures with the highest expression of TLR5 genes in intestinal samples, compared to the control group.

Conclusion: Our results indicated that the inclusion of probiotics enriched with micronutrients and vitamins significantly enhanced the immunogenicity of the PastoCovac® vaccine. Based on the recommendation to administer third and fourth vaccine doses, particularly for vulnerable and elderly individuals, the utilization of supplements containing probiotics is expected to favorably influence immune responses.