Study On Immune Response Of Goat After Immunized With Toxoplasma Gondii Excreted/Secreted Antigens

Toxoplasma gondii is an obligate intracellular parasite that infects a wide range of hosts, including human and domesticated animals throughout the world.So the toxoplasmsis can harm to people's health and cause considerable economic loss in the farming industry. The development of an effective vaccine against Toxoplasma gondii would be of great value to both human and veterinary medicine.To elucidate the immune mechanism of Toxoplasma gondii excreted/secreted antigens on goat, 18 goats were randomly divided into 6 groups, named E/SA group, E/SA+CpG group(no emulsification), E/SA+CpG group, E/SA+IL-2 group, E/SA+ IL-2 +CpG group and the control group. Peripheral blood were collected before the immunization, 2 weeks after immunization, 4 weeks after immunization, 1 week after challenging and 2 weeks after challenging. The specific antibody titer was tested by IHA and the IFN-γ, TNF-α, IL-2 and IL-4 were analyzed by ELISA and the T cells were analyzed by ANAE. The levels of antibody in group 1-5 were 1: 256-1:1024. But the level of the control group is 1:0-1:4. It suggested that the levels of antibody of the immune group had rised. The results showed that the levels of IFN-γ, TNF-α, IL-2 and IL-4 of the immune group were 175.40-215.60, 89.95-253.80, 230.40-301.50 and 39.20-54.20. But the levels were 14.00-18.75, 30.91-42.20, 10.75-18.30 and 20.40-24.60 before the immunization. The levels of the control group were 16.50-36.56, 37.75-58.20, 11.85-21.75 and 21.80-27.60. It suggested that E/SA could stimulated increase of the level of IFN-γ, TNF-α, IL-2 and IL-4 of goats(P<0.05). The levels of T cells of the immune group were 48-55, 48-58, 49-59, 50-60 and 49-63 after immunization, but the level of the control group is 45-56. It suggested that E/SA could stimulated increase of the level of T cell(P<0.05). Atter challenging the temperature of immune goats in 1-5 raise to 40.1-41.1℃and reduced to the normol range within 4 days. The control goats had continuous fever at 41.1～41.7℃for 4-6 days, anorexia and diarrhea. It indicated that immune codition recovered the level before immunization. The level of IFN-γ, TNF-α, IL-2, IL-4, T cells and antibody of the immune group were significantly higher than the control group (P<0.05). Therefore, E/SA could elevate the level cellular immunity and the humoral immunity of goat. The research has laid a foundation for development of goats Toxoplasma gongii vaccine.