PROBLEM TO BE SOLVED: To provide an isolated essentially mammalian negative-sense single stranded RNA virus (MPV) belonging to the sub-family Pneumovirinae of the family Paramyxoviridae and identifiable as phylogenetically corresponding to the genus Metapneumovirus.SOLUTION: Provided is an isolated negative-sense single stranded RNA metapneumovirus comprising an N protein of a specific amino acid sequence, wherein (i) the virus can infect a mammalian cell, (ii) the virus can cause syncytium formation of an infected mammalian cell, (iii) the virus forms a virus particle of 150 to 600 nm, (iv) the virus is chloroform sensitive, and (v) a tMK cell infected with the virus shows no haemagglutination activity.
VIRUS CAUSING RESPIRATORY TRACT ILLNESS IN SUSCEPTIBLE MAMMALS