Dr. Downer has developed and directed several projects of national and regional significance, including as Principal Investigator and Project Director of the National Minority AIDS Education and Training Center; the AIDS Education Training Center National Multicultural Training Center; the AETC-Capitol Region Telehealth Training Center; the Capitol Region Telehealth Training Center,  and the National HIV Curriculum Integration Program. She developed several curricula, including the e-Curriculum Series, Essentials of HIV Medicine; and Module 6 on Cultural Competence in HIV Care for the Mayo Clinic.  She has served as an Instructor for the Federal Emergency Management Agency’s Emergency Management Institute and has lectured internationally on Cultural Competence and Emergency Management. Internationally, Dr. Downer directs the HIV/HCV workforce-strengthening Caribbean Clinicians Community of Practice (CCCoP) program. CCCoP is currently being conducted in twenty-six Caribbean islands. She has also served as Howard University’s Principal Investigator for the Central Asian Program on AIDS Control in Vulnerable Populations led by John Snow, Inc. (JSI) and funded by USAID.

A recognized expert in this field of nutrition and food security, Dr. Downer has served as Senior Nutrition, Food Security, and HIV/AIDS Technical Advisor for the   United States Agency for International Development. She has also served as Assistant Clinical Professor and Director of Public Health Nutrition Services in the Department of Pediatrics, Child Development Center, Georgetown University Medical School; as Director of Medical Education for the National Organization on Fetal Alcohol Syndrome; and as Adjunct Nutrition Faculty in the School of Public Health and Health Services, Exercise Science Program, George Washington, University. Her professional activities have included as a member of the U.S. Food and Drug Administration Advisory Committee; the FEMA Homeland Security and Emergency Management Program Accreditation Committee; the Washington, D.C. Affordable Care Act, Plan Management Advisory Committee;  and an Advisory Member for the US Federal Trade Commission, Division of Service Industry, Consumer Education Committee on Healthy Weight Management.  She is a former Chair of the Washington District of Columbia’s Health Coordinating Council (SHCC) as well as Chair of the Nutrition & Dietetics Board. She is currently a member of the District of Columbia Developmental Center for AIDS Research and is an active member of the District of Columbia's Medical Reserve Corps. Dr. Downer was inducted as a Fellow of the Academy of Nutrition and Dietetics in 2014.