Relying on a similar protocol that includes a systemic (i.p. and s.c.)adjuvant-driven cockroach antigen (CRA) sensitization, followed by RSV infection and CRA challenges, these studies found that RSV indeed exacerbates type 2 immune responses, including eosinophilia and production of cytokines, such as IL-13 and IL-4, as well as airway hyperresponsiveness (134–136). Here, IL4 is linked to airway hyperresponsiveness.