Sequence of the fusion protein gene of human parainfluenza type 2 virus and its 3' intergenic region: lack of small hydrophobic (SH) gene.

cDNA clones representing the fusion (F) gene of human parainfluenza virus type 2 (PIV-2) were isolated from cDNA libraries constructed from virus-specific mRNA and genomic RNA, and the complete nucleotide sequence of the F gene was determined. The F gene is 1854 nucleotides long and encodes one long open reading frame of 551 amino acids. The cleavage site for activation of the precursor Fo protein is Thr-Arg-Gln-Lys-Arg. The F gene of PIV-2 is most closely related to those of simian virus 5 (SV5) and mumps virus (MuV). Interestingly, although the HN glycoprotein of PIV-2 shows no relatedness to the HA glycoprotein of measles virus (MV), a distinct homology is found in the F proteins of PIV-2 and MV. As concerns F proteins, paramyxoviruses can be divided into two subgroups; that is, PIV-2, SV5, and MuV belong to one group, and HPIV-1, SV, and PIV-3 belong to the other group. Newcastle disease virus (NDV) and MV are intermediate. Coding regions for small hydrophobic (SH) proteins have been found between the HN and F genes of SV5 and MuV, which are the viruses most closely related to PIV-2. However, such a gene could not be detected in two different strains of PIV-2.