Dr. Antoniskis was born and raised in Nebraska and graduated from the University of Nebraska Medical Center. Her internship was at San Francisco General Hospital during the early years of the HIV epidemic, and she went on to pursue additional training in both Internal Medicine and Infectious Diseases at Los Angeles County/USC Medical Center; she is board certified in both of those specialties. She moved to Portland in 1991 to join Kaiser Permanente, where she worked in the Immune Deficiency Clinic (IDC) and the general Infectious Disease department until her retirement in 2017. During her time at KP, she also served as the Director of Clinical Research for the IDC and was Chief of that department for approximately 10 years. She served as the Director of Operations for Medical Specialties for Northwest Permanente from 2012-2017 in addition to her clinical practice.