Evidence that a polyhexameric genome length is preferred, but not strictly required, for efficient mumps virus...

Area of Science:

• Virology
• Molecular Biology
• Genetics

Background:

• Mumps virus (MuV) replication is thought to depend on its genome adhering to the
• rule of six,
• meaning the genome length must be a multiple of six nucleotides for efficient viral replication.
• Deviations from this rule can impact viral propagation and genome stability.

Purpose of the Study:

• To investigate the necessity of the
• rule of six
• for efficient Mumps virus replication.
• To analyze the impact of nonpolyhexameric genome lengths (6n-1 and 6n+1) on MuV gene expression and viral recovery.

Main Methods:

• Construction and analysis of Mumps virus minigenomes with nonpolyhexameric lengths (6n-1 and 6n+1).
• Measurement of reporter gene (CAT) expression from minigenomes of varying lengths.
• Rescue and serial passage of Mumps virus from cDNA templates encoding 6n+1 or 6n-1 genomes.

Main Results:

• Reporter gene expression was significantly reduced in nonpolyhexameric minigenomes compared to the wild-type 6n genome.
• The 6n-1 minigenome exhibited a more pronounced reduction in expression than the 6n+1 minigenome.
• Viruses rescued from 6n-1 cDNA rapidly acquired length-correcting mutations, while those from 6n+1 cDNA maintained their nonpolyhexameric length over multiple replication cycles.

Conclusions:

• Polyhexameric genomes are preferred templates for the Mumps virus RNA polymerase, optimizing replication.
• The
• rule of six
• requirement for Mumps virus replication is not absolute, as viruses can tolerate and adapt to nonpolyhexameric genome lengths.