Complete Nucleotide Sequence of a Mumps Virus SP Strain Isolated in China

The complete nucleotide sequence of the mumps virus SP, which was isolated in China, was determined. As with other mumps viruses, its genome was 15 384 nucleotides (nts) in length and encoded seven proteins. The full-length nucleotide sequence of the SP isolate differed from other strains by 4% –6.8% at the nucleotide sequence level. Due to variations of amino acids over the full genome (including the HN and N genes), this isolate exhibited significant variations in the antigenic sites. This report is the first to describe the full-length genome of a genotype F strain and provide an overview of the diversity of genetic characteristics of a circulating mumps virus.

Establishment of an efficient reverse genetic system of Mumps virus S79 from cloned DNA

Background Mumps is a common type of respiratory infectious disease caused by mumps virus(MuV),and can be effectively prevented by vaccination.In this study,a reverse genetic system of MuV that can facilitate the rational design of safer,more efficient mumps vaccine candidates is established.Methods MuV-S79 cDNA clone was assembled into a full-length plasmid by means of the GeneArtTM High-Order Genetic Assembly System,and was rescued via reverse genetic technology.RT-PCR,sequencing,and immunofluorescence assays were used for rMuV-S79 authentication.Viral replication kinetics and in vivo experimental models were used to evaluate the replication,safety,and immunogenicity of rMuV-S79.Results A full-length cDNA clone of MuV-S79 in the assembly process was generated by a novel plasmid assemble strategy,and a robust reverse genetic system of MuV-S79 was successfully established.The established rMuV-S79 strain could reach a high virus titer in vitro.The average viral titer of rMuV-S79 in the lung tissues was 2.68±0.14 log10PFU/g lung tissue,and rMuV-S79 group did not induce inflammation in the lung tissues in cotton rats.Neutralizing antibody titers induced by rMuV-S79 were high,long-lasting and could provide complete protection against MuV wild strain challenge.Conclusion We have established a robust reverse genetic system of MuV-S79 which can facilitate the optimization of mumps vaccines.rMuV-S79 rescued could reach a high virus titer and the safety was proven in vivo.It could also provide complete protection against MuV wild strain challenge.

Development of Improved Mumps Vaccine Candidates by Mutating Viral mRNA Cap Methyltransferase Sites in the Large Polymerase Protein

Although a live attenuated vaccine is available for controlling mumps virus(MuV), mumps still outbreaks frequently worldwide. The attenuated MuV vaccine strain S79 is widely used in mumps vaccination in China, but still with many shortcomings, among which the most prominent are the side effects and decreased immunity. Therefore, there is a need to further improve the safety and efficacy of the current MuV vaccine. In the present study, we further attenuated MuV S79 vaccine strain by inhibiting viral mRNA methyltransferase(MTase). We generated a panel of eight recombinant MuVs(rMuVs) carrying mutations in the MTase catalytic site or S-adenosylmethionine(SAM) binding site in the large(L) polymerase protein. These rMuVs are genetically stable and seven rMuVs are more attenuated in replication in cell culture and five r MuVs are more attenuated in replication in lungs of cotton rats compared with the parental vaccine strain S79. Importantly, cotton rats vaccinated with these seven rMuV mutants produced high levels of serum neutralizing antibodies and were completely protected against challenge with a wild-type MuV strain(genotype F). Therefore, our results demonstrate that alteration in the MTase catalytic site or SAM binding site in MuV L protein improves the safety or the immunogenicity of the MuV vaccine and thus mRNA cap MTase may be an effective target for the development of new vaccine candidates for MuV.

Attenuated MuV-S79 as vector stably expressing foreign gene

Background To describe mumps virus(MuV)used as a vector to express enhanced green fluorescent protein(EGFP)or red fluorescent protein(RFP)genes.Methods Molecular cloning technique was applied to establish the cDNA clones of recombinant mumps viruses(rMuVs).rMuVs were recovered based on our reverse genetic system of MuV-S79.The properties of rMuVs were determined by growth curve,plaque assay,fluorescent microscopy and determination of fluorescent intensity.Results Three recombinant viruses replicated well in Vero cells and similarly as parental rMuV-S79,expressed heterologous genes in high levels,and were genetically stable in at least 15 passages.Conclusion rMuV-S79 is a promising platform to accommodate foreign genes like marker genes,other antigens and immunomodulators for addressing various diseases.