Discrimination of mumps virus small hydrophobic gene deletion effects from gene translation effects on virus virulence.

Deletion of the small hydrophobic (SH) protein of certain paramyxoviruses has been found to result in attenuation, suggesting that the SH protein is a virulence factor. To investigate the role of the mumps virus (MuV) SH protein in virulence, multiple stop codons were introduced into the open reading frame (ORF) of a MuV molecular clone (r88-1961(SHstop)), preserving genome structure but precluding production of the SH protein. No differences in neurovirulence were seen between the wild-type and the SH(stop) viruses.