Schematic representation of the experimental protocol.

<p>Adult female BALB/c mice were infected with influenza A or media only 21 days before they were sensitized with HDM. This involved intranasal exposure to 10 µg of HDM in saline or 50µL of saline for 5 days during weeks 1 and 4, followed by intranasal exposure to 100 µg of HDM in saline or 50µL of saline for 3 days in week 7. Serum samples were collected after the last challenge of week 1, 4, and 7. BAL samples were collected after the last challenge at week 7.