Furthermore, in vivo studies of infants with RSV bronchiolitis have found blood levels of ECP to be higher during convalescence than during acute disease and therefore possibly play a role in the development of the long-standing inflammatory reaction seen in the airways after RSV bronchiolitis, and in which eosinophils play an important role [24,25]. This evidence concerns the gene RNASE3 and respiratory syncytial virus bronchiolitis.