Molecular Cloning and Characterization of Six Genes, Determination of Gene Order and Intergenic Sequences and Leader Sequence of Mumps Virus

Summary mRNA isolated from mumps virus-infected Vero cells was converted into cDNA and cloned into the PstI site of the plasmid pBR322. After screening with 32P-labelled cDNA synthesized from poly(A)+ RNA of uninfected or mumps virus-infected Vero cells, five different groups of virus-specific clones were obtained. The virus specificity of the clones was confirmed by Northern blot analysis, in which the cDNA inserts from the five different groups hybridized to mRNAs of about 2100, 1500, 1450, 2000 and 2200 nucleotides. By the use of oligonucleotides synthesized on the basis of sequences obtained from the five cDNA clones and mRNAs, the sequence of the intergenic and surrounding areas was determined. During genome sequencing, a separate gene was identified between the fusion protein (F) gene and the haemagglutinin-neuraminidase protein (HN) gene. Using oligonucleotides synthesized on the basis of the new gene sequence, cDNA clones with poly(A) were isolated from the cDNA library. The gene order was determined to be 3′ NC-P-M-F-SH-HN-L 5′ (where NC, P, M, SH, and L represent the genes for the nucleocapsid, phosphoprotein or polymerase-associated, matrix or membrane, small hydrophobic and large proteins respectively). There is one nucleotide between the P and M (A), M and F (A), and HN and L genes (G), two between the NC and P (AA) and SH and HN (3′-CG) genes, and seven between the F and SH genes (3′ GAUUUUA) as intergenic sequence. The leader sequence at the 3′ end of the genome has been determined by sequencing the dicistronic leader-NC mRNA using oligonucleotide primers. The sequence from the 3′ terminus to the NC gene start of the mumps virus genome is similar in length (55 nucleotides) to that present in Sendai virus, Newcastle disease virus and parainfluenza virus type 3, and the first five nucleotides are conserved in all negative-stranded RNA virus genomes sequenced to date.