Differential production of inflammatory cytokines in primary infection with human metapneumovirus and with other common respiratory viruses of infancy.

Viral respiratory infections are the most frequent cause of hospital admission for infants and young children during winter. However, the mechanisms of illness that are associated with viral lower-respiratory-tract infection (LRI) are unclear. A widely accepted hypothesis attributes the pathogenesis of viral LRI in infants to the induction of innate inflammatory responses.