Antigenic characterization of small, round-structured viruses by immune electron microscopy.

Area of Science:

• Virology
• Public Health
• Epidemiology

Background:

• Nonbacterial gastroenteritis outbreaks were common in Japan between 1977 and 1988.
• Small, round-structured viruses (SRSVs) were identified as a cause of these outbreaks.

Purpose of the Study:

• To classify SRSVs detected in Japanese gastroenteritis outbreaks into distinct antigenic patterns.
• To examine the antigenic relatedness of these SRSV patterns to known agents like Norwalk, Hawaii, and Otofuke.

Main Methods:

• Cross-immune electron microscopy (IEM) was used to classify SRSVs into nine antigenic patterns (S-1 to S-9).
• Antisera to Norwalk, Hawaii, and Otofuke agents were used in IEM to assess antigenic relatedness.
• The prevalence of each antigenic pattern was determined across 38 outbreaks.

Main Results:

• Nine distinct SRSV antigenic patterns (S-1 to S-9) were identified.
• SRSV patterns S-3 to S-9 showed some antigenic relatedness to each other and to Norwalk, Hawaii, and Otofuke agents.
• SRSV-8 was the most prevalent pattern, implicated in 24% of the examined outbreaks, followed by S-5 (16%), S-4 (13%), and S-9 (13%).

Conclusions:

• SRSVs circulating in Japan during 1977-1988 exhibited diverse antigenic patterns.
• Specific SRSV patterns showed varying degrees of antigenic relatedness to established viral agents.
• SRSV-8 emerged as a significant cause of gastroenteritis outbreaks in the studied Japanese population.