Ferdowsi University of Mashhad Iranian Journal of Veterinary Science and Technology 2008-465X 18 3 2026 07 01 Comparison of the Immunogenicity of Different Proportions of Chitosan Adjuvant in an Attenuated Neospora caninum Vaccine in BALB/c Mice 53 58 47432 10.22067/ijvst.2025.94043.1567 EN Seyed Reza Hosseini Department of Veterinary, Shk. C., Islamic Azad University, Shahrekord, Iran. 0000-0002-2553-4004 Marzieh Kefayat Department of Parasitology, Ka. C., Islamic Azad University, Karaj, Iran. Milad Hamzehali Tehrani Department of Pathobiology, Faculty of Veterinary, Science and Research Branch, Islamic Azad University, Tehran, Iran. 0000-0002-6681-0837 Amir Hosein Norouzi Department of Parasitology, Ka. C., Islamic Azad University, Karaj, Iran. Journal Article 2025 07 26 Neosporosis is a neuromuscular infectious disease in dogs caused by the protozoan N. caninum. This disease is globally distributed; canines are the definitive hosts, while a wide range of animals serve as intermediate hosts. This study aimed to compare the immunogenicity of different proportions of chitosan adjuvant in an attenuated N. caninum vaccine in BALB/c mice. Twenty-eight BALB/c mice were divided into four groups (n = 7 per group). Groups 1, 2, and 3 were subcutaneously immunized with attenuated tachyzoites of N. caninum strain Nc-1 combined with micronized chitosan adjuvant at concentrations of 10%, 50%, and 90%, respectively. Group 4 served as the negative control and did not receive any vaccine formulation or adjuvant. All groups were monitored daily over a three-week period. Following sample collection, antibody levels were quantified using ELISA, and cellular immune responses were evaluated by measuring IFN-γ levels with a commercial assay kit. According to ELISA results, the highest antibody levels were observed in the group immunized with the attenuated N. caninum strain containing 90% chitosan adjuvant, showing significantly higher antibody levels compared to the control and other groups (p < 0.05). Similarly, IFN-γ analysis revealed that the strongest IFN-γ-associated immune response was observed in the group immunized with 90% chitosan adjuvant, with significant differences compared to the control and other groups (p < 0.05).Statistical analysis was performed using one-way ANOVA followed by Tukey's post-hoc test for multiple comparisons. Based on these findings and the considerable effect of chitosan adjuvant on both antibody levels and IFN-γ-associated cellular immunity, these findings support further investigation of chitosan-containing formulations as potential adjuvants for Neospora vaccine development. https://ijvst.um.ac.ir/article_47432_c16f522d08b34a5ea1b6e7c65b14fa9d.pdf