Roles of Toxoplasma gondii-derived heat shock protein 70 in host defense against T-gondii infection

C57BL/6 mice receiving intraperitoneal injection of Toxoplasma gondii-derived heat shock protein 70 (Tg.HSP70) on day 3 post T gondii infection succumbed by day 9 post infection, while vector protein-injected control mice survived more than 6 months. The deteriorating effect of Tg.HSP70 on host immune responses was dose-dependent. By Tg.HSP70 injection, T gondii loads increased in various organs of T gondii-infected mice. Th2 cytokines such as IL-4 and IL-10 were continuously produced from spleen and peritoneal exudate cells of T gondii-infected mice by injection of Tg.HSP70. Furthermore, nitric oxide production from peritoneal macrophages in T gondii-infected mice was reduced by Tg.HSP70.