Titer is a quantitative measure of the concentration or amount of a specific biological entity — such as a viral vector, antibody, or recombinant protein — present in a given sample volume, typically expressed in units per milliliter (U/mL), genome copies per milliliter (GC/mL), or transducing units per milliliter (TU/mL). In biopharmaceutical manufacturing and viral vector production, titer is a critical process performance indicator that reflects upstream productivity and directly influences downstream yield, manufacturing costs, and batch consistency. Achieving and maintaining high titer is a primary objective of upstream process development and process optimization in CDMO operations
