Because of different funding mechanisms, the cost will fall into three different categories: Harvard University Center for AIDS Research (HU CFAR) members, other academic including Harvard Medical School (HMS) non-AIDS researchers, and corporate. In all cases, the cost is based on a per mouse model which will include purchase, housing expenses as defined by DFCI Animal Research Facility (ARF), human tissue/cell engraftment and immune reconstitution monitoring cost. Depending on the model chosen, immune reconstitution could take up to 12-16 weeks to complete thus the mouse housing expense would vary. Once reconstructed, the humanized mice may be transferred to the investigator's facility or further experiments may be conducted at DFCI ARF per prior agreement with the investigator bearing the per diem and any applicable costs. Academic investigators are expected to set up a billing structure with the mouse purchasing and initial reconstitution per diem cost paid up front and other applicable expenses billed as it occurs. Corporate projects requires individual research and pay structure agreements set in place prior to starting the project.