The mumps virus nucleocapsid mRNA sequence and homology among the Paramyxoviridae proteins

The nucleotide sequence of mumps virus nucleocapsid protein (NP) mRNA has been determined from two overlapping cDNA clones and confirmed by partial sequencing of the mRNA and the genome. The mRNA contains 1844 nucleotides excluding poly(A) and encodes a protein of 553 amino acids with a calculated molecular weight of 61,792. A comparison of the mumps virus nucleocapsid protein sequence with that of other paramyxoviruses revealed a moderate degree of homology (33.1%) with the Newcastle disease virus (NDV) only. The nucleocapsid proteins of all paramyxoviruses studied to date, excluding that of the genus pneumovirus, have a conserved sequence of six amino acids (Ser-Tyr-Ala-Met-Gly-Val) except that of NDV which has a mismatch of two amino acids (Ser-Phe-Ala-Met-Gly-Met) in that sequence. In addition, there is another conserved region of seven amino acids (Phe-Ala-Pro-Gly-X-Tyr-Pro) in the nucleocapsid proteins of mumps virus, Sendai virus and parainfluenza virus type 3. The nucleocapsid proteins of measles virus and canine distemper virus (CDV) also have this conserved region but with three conservative amino acid changes.