The claimed invention is directed towards the generation of pluripotent, multipotent, and/or self-renewing cells which are capable of beginning to differentiate in culture into a variety of cell types and capable of further differentiation in vivo. The claimed invention is also directed towards the generation of desirable, differentiating cell populations transplantable to patients, genetic modification of endogenous cells, and the treatment of patients suffering from diseases that may be ameliorated by these methods. This invention also provides methods for preventing, treating, or retarding disease related to immunodeficiency virus (e.g. HIV-I, HIV-2, SIV, FIV, etc.) infection.