Evaluation of two aluminum adjuvant on DNA vaccine containing ROP1 gene of Toxoplasma gondii (RH strain) for immunity and survival assay in animal model

Toxoplasmosis can lead to severe pathological effects in both infected humans and animals. The various DNA vaccines against Toxoplasma compose of single or cocktail antigens have been investigated but they have partial protective against disease. In this study, we used pcROP1 as a DNA vaccine and aluminium phosphate and aluminium hydroxide to compare their efficacy as mineral adjuvants. BALB/c mice immunized with pcROP1 alone or with co-administration of Alpo4 or Alum and the effectiveness of these two adjuvants were compared using lymphocyte proliferation assay, cytokine and antibody assay and survival time. The group co-administered alum elicited stronger humoral and Th1-type cellular immune responses than the group co-administered Alpo4, while immune response in group administered with pcROP1 alone is higher than them. When challenged with Toxoplasma gondii RH strain, mice immunized with or without alum had significantly higher survival rates, whereas there was no notable enhancement of survival rate in Alpo4 group (P≤0.05). Our result suggest that pcROP1 plus alum and aluminium phosphate not strongly potentiate the efficacy of this DNA.