Complete nucleotide sequence of the hemagglutinin-neuraminidase (HN) mRNA of mumps virus and comparison of paramyxovirus HN proteins

The complete nucleotide sequence of the hemagglutinin-neuraminidase protein (HN) mRNA of the virulent SBL-1 strain of mumps virus has been determined. The mRNA contains 1887 nucleotides excluding the poly(A). The protein encoded by the mRNA has 582 amino acids and a membrane anchorage domain near the amino terminus. The calculated molecular mass (64 kDa) of the protein is in good agreement with that of the unglycosylated HN protein (63 kDa) identified in tunicamycin treated mumps virus infected cells (Herrler and Compans, 1983). The predicted sequence has nine potential N-glycosylation sites out of which two contain a cysteine residue and one has a proline residue as the variable amino acid X in the glycosylation site (Asn-X-Ser or Asn-X-Thr) and therefore, may not be utilized. One potential glycosylation site is in the cytoplasmic region which may not also be glycosylated. Comparison of the mumps HN protein sequence with the HN protein sequences of Sendai virus, simian-virus 5 (SV5), parainfluenza virus type 3 and Newcastle disease virus (NDV) shows two major homology regions, one region near the middle of the protein and the other in the second half of the molecule. In terms of percentage amino acid homology, the HN proteins of mumps virus, SV5 and NDV are closely related to each other but distinct from Sendai virus and parainfluenza virus type 3 HN proteins.