Influenza viruses continue to cause severe morbidity and remain a
continuous pandemic threat. Virus challenge studies in animal models are
performed during preclinical vaccine development. Improved methods are
needed to improve data quality in animal models to reduce both animal
stress and the animal numbers. By evaluating automated activity monitors
as a tool for Influenza vaccine development, we demonstrate that
activity in mice declines after viral challenge and that this reduction
in activity can be prevented by vaccination. Notably, the decline in
activity precedes weight loss and could thus provide an objective and
early endpoint in Influenza virus challenge studies.