Influenza viral load in the lungs of 20 month old mice, 6 days after infection. Copyright 2005 The American Association of Immunologists, Inc. *P< 0.001 when compared with the control group. These mice had expression plasmids containing either the IL-7 gene, the fusion protein (the extracellular portion of the chemokine receptor CCR9 and interleukin-7) gene, or a sham control gene (the N-terminal portion of CCR9) inserted into their anterior tibial muscle approximately 2 months previously .
Aspinall et al. Immunity & Ageing 2007 4:9 doi:10.1186/1742-4933-4-9