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[Reversion in the natural variability of influenza A virus]
Abstract:
In mid-November, 1977, local outbreaks of acute respiratory diseases (ARD) in institutionalized communities began to be recorded in a number of geographical zones of the USSR, and by the end of the month a general increase in the incidence was observed in some areas of the country. The epidemic outbreaks extended gradually and were characterized by moderate development involving mainly young subjects. The strains causing the epidemic had no antigenic relationship with reference A (H3N2) virus and the H1 test were neutralized with antisera to influenza A virus with the antigenic formula H1N1 to 1 1/4 titer. Their neuraminidase was inhibited by the antiserum to the recombinants containing neuraminidase of the subtype N1, especially A/New Jersey 8/76. These results permit to classify the strains causing the epidemic outbreaks in November--December, 1977, as influenza A virus with the antigenic formula H1N1.
Insights
In late 1977, outbreaks of acute respiratory disease (ARD) were identified in the USSR. These were caused by a novel influenza A virus strain with the H1N1 antigenic formula.
Area of Science:
- Virology
- Epidemiology
- Public Health
Background:
- In November 1977, localized outbreaks of acute respiratory diseases (ARD) were reported in institutionalized communities across the USSR.
- By the end of November, a nationwide increase in incidence was observed, particularly affecting young individuals.
Purpose of the Study:
- To identify and characterize the etiological agent responsible for the 1977 USSR influenza outbreaks.
- To determine the antigenic properties and classification of the circulating influenza virus strains.
Main Methods:
- Antigenic characterization of the epidemic strains using reference antisera.
- Hemagglutinin-neuraminidase (HN) analysis through neutralization and inhibition assays.
- Comparison with known influenza A virus subtypes, including A (H3N2).
Main Results:
- The epidemic strains showed no antigenic relationship with the A (H3N2) virus.
- The strains were neutralized by antisera to influenza A virus with the H1N1 antigenic formula.
- Neuraminidase activity was inhibited by antiserum to subtype N1, specifically A/New Jersey 8/76.
Conclusions:
- The strains causing the November-December 1977 outbreaks in the USSR were identified as influenza A virus.
- The confirmed antigenic formula for these strains was H1N1, indicating a significant public health event.