Background and Aims: Wild-type RS-12 strain of mumps virus has been isolated from an Iranian patient and has been attenuated after several serial passages. This study was designed to determine nucleotide and amino acid substitutions in the HN, F and SH genes during attenuation of the wild-type virus.
Materials and Methods: Required viral samples prepared at Razi Vaccine and Serum Institute. Viral RNA was extracted, targeted segments were amplified and sequenced and finally were analyzed using DNAMAN software.
Results: No difference in nucleotide and deduced amino acid sequence of the F and SH genes was detected following attenuation of wild-type as compared to the vaccine strain, but four nucleotide changes in HN gene had occurred which had resulted in two nucleotide differences.