Immunological evaluation of a DNA cocktail vaccine with co-delivery of calcium phosphate nanoparticles (CaPNs) against the Toxoplasma gondii RH strain in BALB/c mice

Many recent studies have been conducted to evaluate protective immunity mediated by DNA vaccines against toxoplasmosis. Cocktail DNA vaccines showed better immune responses compared to single vaccines. The objective of the current study was to evaluate the protective efficacy of rhomboid 4 (ROM4) and cocktail DNA vaccines (ROM4 + GRA14) of the Toxoplasma gondii RH strain with or without coated calcium phosphate nanoparticles (CaPNs) as the adjuvant to improve the immunogenicity against the T. gondii RH strain in BALB/c mice. Cocktail DNA vaccines of pcROM4 + pcGRA14 of the T. gondii RH strain were constructed. CaPNs were synthesized and the cocktail DNA vaccine was coated with the adjuvant of CaPNs. Immunogenicity and the protective effects of cocktail DNA vaccines with or without CaPNs against lethal challenge were evaluated in BALB/c mice. pcROM4 and cocktail DNA vaccine coated with CaPNs significantly enhanced cellular and humoral immune responses against Toxoplasma compared to pcROM4 and cocktail DNA vaccine without CaPNs ( p