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Antigenic relationships between human caliciviruses and Norwalk virus
W D Cubitt1, N R Blacklow, J E Herrmann
1Public Health Laboratory, Central Middlesex Hospital, London, England.
Abstract:
We investigated antigenic relationships between human calicivirus (HCV) strains and Norwalk virus by using immune electron microscopy (IEM) and radioimmunoassay (RIA). Three serologically distinct HCV strains, UK1, UK2, and Japan, were demonstrated by IEM, as was evidence for two additional strains, UK3 and UK4. Although HCV strains and Norwalk virus were distinct by IEM, 12 of 20 patients with gastroenteritis due to HCV UK4 and two of eight with gastroenteritis due to UK2 showed seroconversions to Norwalk virus by RIA. These naturally occurring antibody responses in humans, as detected by RIA, support the concept that Norwalk virus belongs to the family Caliciviridae. An RIA for HCV Japan antigen also detected HCV UK1, UK2, and UK4 and thus appears to identify a group-specific antigen for these viruses. An RIA for antibody to HCV Japan failed to identify seroconversions in 45 of 47 patients with gastroenteritis due to HCV UK. These results may reflect different reactivities of various immunologic tests for the identification of infections due to small gastroenteritis viruses.
Insights
This study explored human calicivirus (HCV) and Norwalk virus relationships using immune electron microscopy and radioimmunoassay. RIA detected cross-reactivity, suggesting Norwalk virus belongs to the Caliciviridae family.
Area of Science:
- Virology
- Immunology
- Gastroenterology
Background:
- Human caliciviruses (HCVs) are significant causes of gastroenteritis.
- Understanding antigenic relationships between different viral strains is crucial for diagnostics and epidemiology.
- Norwalk virus is a prominent member of the Caliciviridae family, but its precise relationship with other HCVs requires further investigation.
Purpose of the Study:
- To investigate the antigenic relationships between various human calicivirus (HCV) strains and Norwalk virus.
- To determine if cross-reactivity exists between HCV strains and Norwalk virus using immunological methods.
- To assess the utility of different immunoassays in identifying infections caused by small, non-cultivable gastroenteritis viruses.
Main Methods:
- Immune electron microscopy (IEM) was employed to visualize and differentiate viral strains.
- Radioimmunoassay (RIA) was utilized to detect specific antibodies and antigens, assessing cross-reactivity.
- Patient serum samples from gastroenteritis cases were analyzed for seroconversions.
Main Results:
- Three distinct HCV strains (UK1, UK2, Japan) and evidence for two additional strains (UK3, UK4) were identified by IEM.
- While IEM showed distinctness between HCV strains and Norwalk virus, RIA revealed seroconversions to Norwalk virus in patients infected with HCV UK4 and UK2.
- A group-specific antigen for HCV Japan, UK1, UK2, and UK4 was identified by RIA, though antibody detection showed limited cross-reactivity.
Conclusions:
- The observed antibody responses detected by RIA support the classification of Norwalk virus within the Caliciviridae family.
- RIA for HCV Japan antigen demonstrated group specificity for multiple HCV strains, aiding in their identification.
- Discrepancies in seroconversion detection highlight the varied reactivities of different immunologic tests for small gastroenteritis viruses.