Differences in plaque size and VP4 sequence found in SA11 virus clones having simian authentic VP4

Area of Science:

• Virology
• Molecular Biology
• Genetics

Background:

• Rotaviruses, such as Simian rotavirus SA11 (SA11), are a significant cause of gastroenteritis in infants and young children.
• Viral plaque size is a measurable characteristic that can be influenced by genetic factors and is often used in viral characterization and propagation.

Purpose of the Study:

• To investigate the genetic basis for differences in plaque size among SA11 virus clones.
• To identify specific viral genes or proteins associated with variations in plaque morphology.

Main Methods:

• Isolation and characterization of stable SA11 virus clones with distinct plaque sizes.
• Analysis of viral RNA segments using polyacrylamide gel electrophoresis.
• Nucleotide sequencing of the fourth RNA segment to determine VP4 protein sequences.
• Generation of single-gene reassortant viruses to assess the role of specific RNA segments.

Main Results:

• Five stable SA11 clones with varying plaque sizes were successfully isolated.
• Electrophoretic analysis revealed differences in the migration patterns of RNA segments 4, 5, and 7 between large and small plaque clones.
• Sequencing of RNA segment 4 identified a five-amino-acid difference in the VP4 protein between large and small plaque SA11 clones.
• A reassortant virus with RNA segment 4 from a large plaque clone exhibited large plaque formation, implicating VP4 in plaque size determination.

Conclusions:

• The five-amino-acid difference in the VP4 protein is strongly associated with the observed differences in plaque size among SA11 virus clones.
• This finding suggests that VP4 plays a crucial role in determining the plaque phenotype of SA11 rotavirus.