Improved Alum Containing Adjuvant by Vitamin A for Enhancing Immune Responses and Efficacy of Leptospira Vaccine in Hamster Model

Abstract

Use of suitable adjuvant is one of the priorities in vaccine and immune modulation, stimulation and potentiating. Vaccination is effective for prevention and treatment of bacterial diseases including Leptospirosis. In the present study, we prepared Leptospiral vaccine with Alum, modified Alum adjuvant (mAlum) and without adjuvant. Vaccination was done; then we evaluated the immune responses by isolating the splenocytes and sera for interleukin (IL) profiles (the highest level of all cytokines except IL-4 and IL-12 was obtained in the mAlum antigen group at week 7 post-treatment). Moreover, the expression of all evaluated cytokines in the mAlum group was greater than in the other groups at week 62. Significant increases in antibody titters were noted in the mAlum and Alum group, challenged interaperitionelly with a lethal dose of virulent and monitored pathological lesion that moderate to severe lesions with score 3 were observed in the control group while the animals immunized with mAlum-antigen and Alum-antigen displayed slight to mild lesions with an average score of 0.5. The results demonstrated that modified Alum Adjuvants are better than Alum adjuvants as revealed by the enhanced long-term antibody responses. None of the vaccinated animals died from the challenge experiment 84 day post-injection except those vaccinated with saline vaccine. We assume that these observations affirmatively assign a pivotal vitamin a role to adjuvant formulation and preparation in type and extent of immune responses raised in the vaccinated animals.