Evaluation of survival rate using liposome containing soluble antigens (SA) against Toxoplasma gondii infection in BALB/c mice

Toxoplasma gondii, an obligate intracellular protozoan parasite, is widespread across the world. It causes congenital disease and abortion in humans and domestic animals. One of the major concerns in parasitology, thus, is an effective vaccine development to control Toxoplasmosis.

In the present research, a nano-liposomal vaccine containing soluble antigens (SA) was designed to evaluate the immunity and protective efficacy against T. gondii infection in BALB/c mice. Soluble antigens (SA) were achieved from tachyzoites, encapsulated in the liposome, and investigated via scanning electron microscope. Three times with 2-week intervals, BALB/c mice were immunized subcutaneously with different formulations. The level of protection against infection was assessed through the percent survival survey of BALB/c mice after challenge with tachyzoites of T. gondii RH strain; also, the type of generated immune response was determined by evaluating the generation of cytokine (IFN-γ, IL-4) and titration of IgG isotypes.

The immunization with liposome DSPC+ SA and liposome DSPC+ Imiquimod + SA induced a substantial increase in anti-Toxoplasma IgG antibody as compared to the PBS group (p <0.05). The IgG2a and IFN-γ secretion highest levels were seen with liposome DSPC+ Imiquimod + SA more than the control group (p <0.01) and (p <0.0001), respectively. After challenge with tachyzoites, less mortality was detected in the immunized mice by liposome DSPC + Imiquimod + SA that was meaningfully different (p <0.01) in comparison to other groups.

Vaccination with liposome DSPC + Imiquimod + SA showed more survival rate and cellular immune reaction against T. gondii.