VP4 Mutation Boosts Replication of Recombinant Human/Simian Rotavirus in Cell Culture

Area of Science:

• Virology
• Vaccinology
• Molecular Biology

Background:

• Rotavirus A (RVA) is a major cause of severe diarrhea and mortality in children, particularly in Sub-Saharan Africa.
• Current vaccine development aims to target diverse African RVA genotypes.

Purpose of the Study:

• To generate next-generation RVA vaccines against African genotypes using a reverse genetics system.
• To enhance the rescue and replication efficiency of reassortant RVA strains in cell culture.

Main Methods:

• A simian rotavirus reverse genetics system was employed to exchange VP4, VP7, and VP6 genes with those from African human RVA strains.
• Reassortant viruses were rescued, passaged, and analyzed via whole-genome sequencing.
• Site-directed mutagenesis was used to introduce specific VP4 mutations.

Main Results:

• A G9-P[6]-I2 triple-reassortant RVA initially showed poor replication but improved upon passaging.
• Whole-genome sequencing identified a single point mutation (A797G) in VP4 (E263G) responsible for enhanced replication.
• Introducing this mutation into the VP4 plasmid significantly increased the replication of both mono-reassortant and triple-reassortant viruses.
• The beneficial effect of the mutation was strain-specific.

Conclusions:

• Specific point mutations in the VP4 protein can substantially enhance the rescue and replication of recombinant RVA reassortants in cell culture.
• This finding is valuable for developing novel RVA vaccine strains, particularly against prevalent African genotypes.