Sequence analysis of the matrix protein gene of human parainfluenza virus type 3: extensive sequence homology among paramyxoviruses

The sequences of the human parainfluenza virus type 3 (PIV3) matrix (M) mRNA [1150 nucleotides exclusive of poly(A)] and predicted M protein (353 amino acids) were determined by sequence analysis of cloned cDNA and viral genomic RNA. The gene-end sequence of the M gene differed from the semi-conserved gene-end sequence of the other PIV3 genes by an apparent insertion of eight nucleotides. The PIV3 M protein shared high sequence homolggy with Sendai virus and moderate homology with measles virus and canine distemper virus. Statistical analysis of the available sequences showed that the M protein was the most highly conserved parainfluenza viralprotein. Human parainfluenza virus type 3 (PIV3) is second in importance only to respiratory syncytial virus (RSV) as a major aetiological gent of bronchiolitis and pneumonia in infants (Chanock & McIntosh, 1985). The genome of PIV3 is a single strand of negative-sense RNA of approximately 15000 nucleotides that codes for seven unique polypeptides (Storey et al., 1984