Unusual, stable replicating viruses generated from mumps virus cDNA clones

Area of Science:

• Virology
• Molecular Biology
• Genetics

Background:

• Reverse genetics allows for the creation of modified viruses.
• Mumps virus (MuV) is a paramyxovirus with a segmented RNA genome.
• Understanding viral mutation patterns is crucial for studying viral evolution and pathogenesis.

Purpose of the Study:

• To investigate the generation and stability of recombinant mumps viruses (rMuV) with clustered mutations.
• To characterize the nature and frequency of mutations in specific viral genomic regions.
• To explore the stability of these mutations during serial passage in different cell types.

Main Methods:

• Isolation and characterization of recombinant mumps viruses (rMuV) using reverse genetics.
• Next-generation sequencing to identify and quantify mutations in the viral genome.
• Serial passage of rMuV in Vero cells and human B-lymphocyte cell lines (B-LCL).
• Analysis of mutation stability and frequency during passage.

Main Results:

• Two rMuV strains were generated, one with 11 mutations in the V/P region and another with 32 mutations in the N gene.
• The majority of observed mutations (48/51) were synonymous, a pattern not seen in natural MuV isolates.
• Mutations were stable across multiple passages in both Vero and B-LCL cells, with no reversion to the consensus sequence.
• Defective interfering RNAs accumulated during passage in Vero cells but not in B-LCL cells.
• The EGFP gene, when present, showed variation levels similar to viral genes, irrespective of functional constraints.

Conclusions:

• Reverse genetics can produce rMuV with unique, clustered, and stable synonymous mutations.
• The mechanism generating these specific mutation patterns and their stability is currently unknown.
• The stability of these mutations suggests potential implications for viral genetic engineering and research.