An increased frequency of Toxoplasma encephalitis has been reported in AIDS patients, especially those with significant immunosuppression when CD4 T lymphocyte cell counts is <200 cells/μL, and T. gondii infection is regarded as an important opportunistic pathogen that lead to the death of AIDS patients (Luft et al., 1993; Jones et al., 1996). This evidence concerns the gene CD4 and AIDS.