Prior to infection, the levels of the Elane transcripts were significantly higher in DBA/2J mice, were somewhat higher (1.3 fold) in C57Bl/6J at day 1 p.i and became significantly higher at day 3 p.i. and comparable levels were observed in both mouse strains at day 6 p.i. While the levels of the Ctsd (cathepsin D; also known as aspartyl proteinase) transcripts were significantly higher in C57Bl/6J prior to infection and at day 6 p.i., comparable transcript levels were recorded in the lungs of both strains at day 1 p.i. whereas at day 3 p.i. transcript levels were higher in DBA/2J mice. The gene discussed is CTSD; the disease is infection.