To further address the possibility that increased expressions of GRA1, GRA2, GRA3, GRA7, and ROP35 are involved in the immune evasion of T. gondii cysts to successfully persist in the presence of the perforin-mediated anti-cyst CD8+ T-cell immunity, we examined whether the degree of increase in the relative mRNA expression levels for GRA1, GRA2, GRA3, GRA7, and ROP35 in the cysts directly correlates with their capability to successfully persist through the immune environment in which greater portions of cysts are eliminated. The gene discussed is PRF1; the disease is cyst.