Human metapneumovirus (HMPV or hMPV) is a negative-sense single-stranded RNA virus of the family Pneumoviridae and is closely related to the avian metapneumovirus (AMPV) subgroup C. It was isolated for the first time in 2001 in the Netherlands by using the RAP-PCR (RNA arbitrarily primed PCR) technique for the identification of unknown viruses growing in cultured cells...