Evaluation of the effectiveness of cerium nanoparticles as a potential adjuvant in veterinary rabies vaccine.

Rabies remains a major public health and veterinary concern worldwide, underscoring the need for improved vaccine immunogenicity. Nanomaterials are being looked at for their role in shaping early immune reactions, along with boosting targeted responses to antigens. In this work, particles made of cerium were tested as possible helpers in a vet-approved dead rabies vaccine using mice. Using a method that formed cerium oxide nanoparticles, scientists checked how they looked and behaved. These tiny particles were tested to understand their makeup plus shape. CeNPs were synthesized and characterized for their physical and chemical properties. Subsequently, a mouse model using a standard veterinary rabies vaccine was evaluated for its capacity to elicit a booster response. Animals were immunized with inactivated rabies vaccine formulations with or without CeNPs, and immune responses were assessed by rabies virus neutralizing antibody (RVNA) titers (RFFIT) and serum cytokine levels (IL-4 and IFN-γ). The Rapid Fluorescent Focus Inhibition Test (RFFIT) revealed that NAb titers in the primary cohort (CRV-CeNPs) showed greater variability than those in the reference cohorts (A and B) (P < 0.001). A marked distinction was observed in the levels of interleukin-4 (IL-4) and Interferon gamma (IFN-γ) within the primary cohort (CRV-CeNPs) in contrast to the reference cohorts (P ≤ 0.05). CeNP co-formulation was associated with higher RVNA titers than vaccine alone and modulated systemic cytokine levels. Within the scope of this study, CeNPs demonstrate adjuvant-like activity in an inactivated veterinary rabies vaccine formulation. Safety conclusions are limited to clinical monitoring and survival outcomes; mechanistic and histopathological assessments warrant further dedicated studies.