A major allergen contained in short ragweed pollen. Short ragweed extracts are labeled with AgE concentrations (now called Amb a 1) The concentration of AgE (i.e., Amb a 1) is measured for each manufactured lot of extract, using a standardized assay. Clinical studies have been conducted, which established a therapeutic dose range for Ragweed allergy immunotherapy. Guidelines for dosing are outlined in the Allergy Immunotherapy Practice Parameters.