Capsid protein diversity among Norwalk-like viruses

Area of Science:

• Virology
• Molecular Biology
• Public Health

Background:

• Norwalk-like viruses (NLVs), a major cause of gastroenteritis outbreaks, exhibit significant genetic diversity.
• Understanding the genetic relationships among NLV strains is crucial for epidemiological surveillance and control.

Purpose of the Study:

• To determine the complete capsid gene sequence of 20 NLV strains collected from UK outbreaks.
• To perform phylogenetic analysis to delineate genomic sub-groups within genogroups I and II of NLVs.
• To establish a framework for investigating genetic and antigenic relationships within the NLV calicivirus clade.

Main Methods:

• Sequencing of the complete capsid gene of 20 NLV strains.
• Phylogenetic analysis of obtained sequences alongside 15 published sequences.
• Amino acid identity analysis of different regions of the capsid gene.

Main Results:

• Identified 20 NLV strains, comprising nine genogroup I and eleven genogroup II strains.
• Phylogenetic analysis revealed seven genomic sub-groups within genogroup I and eight within genogroup II, with four novel genogroup II sub-groups.
• Amino acid identities ranged from 37-44% between genogroups and 61-100% within genogroups, with greatest divergence in the central variable region (down to 28%).

Conclusions:

• The study identified 15 distinct genomic sub-groups within NLVs, expanding the known genetic diversity.
• This classification provides a valuable framework for future research into the genetic and antigenic diversity of NLVs.
• The findings contribute to a better understanding of calicivirus evolution and epidemiology.