In conclusion, a large body of new information on the biology and immunology of T. gondii has accumulated in the past several years. Much of this is due to the advent of AIDS and the increased funding made available to researchers interested in opportunistic infections in this patient population. These scientific advances have led to a better understanding of the process by which Toxoplasma infects mammalian host cells, molecular biology and biochemistry of the parasite, antigenic structure and immune response to the infection and approaches to be adopted for drug design and therapeutic strategies. Thus, it is through such recognition of the importance of understanding the basic science of an opportunistic pathogen that such advances can be realized.