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Inter- and intragenus structural variations in caliciviruses and their functional implications
Rong Chen1, John D Neill, Jacqueline S Noel
1Verna and Marrs McLean Department of Biochemistry and Molecular Biology, Alkek Building N410, Baylor College of Medicine, One Baylor Plaza, Houston, TX 77030, USA.
Journal of Virology
|May 28, 2004
Summary
Structural studies of caliciviruses reveal distinct capsid variations, particularly in the P2 subdomain, influencing host specificity and strain diversity. Sapoviruses show closer structural ties to animal caliciviruses than to noroviruses.
Area of Science:
- Virology
- Structural Biology
- Molecular Evolution
Background:
- The Caliciviridae family comprises single-stranded RNA viruses affecting humans and animals, causing gastroenteritis and other illnesses.
- Human caliciviruses are significant causes of nonbacterial gastroenteritis outbreaks.
- Animal caliciviruses can cause host-specific diseases with zoonotic potential.
Purpose of the Study:
- To investigate structural variations within and between Caliciviridae genera.
- To elucidate the structural basis of host specificity and viral strain diversity.
- To compare the structures of representative viruses from Norovirus, Sapovirus, and Vesivirus genera.
Main Methods:
- Performed structural studies on recombinant capsids of Grimsby virus (Norovirus genogroup 2), Parkville virus (Sapovirus), and San Miguel sea lion virus serotype 4 (Vesivirus).
- Conducted comparative structural analysis with the recombinant capsid of Norwalk virus (Norovirus genogroup 1).
- Utilized X-ray crystallography or cryo-electron microscopy for structural determination (implied).
Main Results:
- All studied calicivirus capsids share a T=3 icosahedral framework of capsid protein dimers with S and P domains.
- Significant structural differences were observed, especially in the P2 subdomain of the P domain, correlating with sequence variability.
- Parkville virus (Sapovirus) exhibited greater structural similarity to SMSV4 (Vesivirus) than to noroviruses, suggesting a closer Sapovirus-Vesivirus relationship.
Conclusions:
- The conserved S domain provides an icosahedral scaffold, while the variable P2 subdomain acts as a module for host specificity and diversity.
- The P1 subdomain fine-tunes the positioning of the P2 subdomain.
- Structural similarities suggest a closer evolutionary link between sapoviruses and animal caliciviruses (like Vesivirus) than previously recognized.