STUDIES OF ANTIGENIC DIFFERENCES AMONG STRAINS OF INFLUENZA A BY MEANS OF RED CELL AGGLUTINATION

Area of Science:

• Virology
• Immunology
• Epidemiology

Background:

• Cross-inhibition tests are crucial for understanding influenza virus strain variations.
• Previous studies faced challenges with data variability from red cells, virus suspensions, and antisera.

Purpose of the Study:

• To standardize methods for antigenic comparison of influenza A virus strains.
• To analyze the antigenic patterns of influenza A virus strains from the 1940-41 US epidemic.

Main Methods:

• Developed methods to correct or avoid variability in agglutination inhibition tests.
• Compared antigenic patterns of eighteen influenza A virus strains using ferret antisera.
• Utilized chick embryo inoculation, ferret, and mouse passage for strain isolation.

Main Results:

• Sixteen of eighteen influenza A virus strains from the 1940-41 epidemic showed no significant antigenic differences.
• Two early epidemic strains exhibited slight but significant antigenic variations.
• One 1940-41 strain showed closer antigenic resemblance to the PR8 strain.

Conclusions:

• Established reliable agglutination inhibition techniques for antigenic comparisons of influenza A virus.
• Demonstrated antigenic homogeneity among most influenza A strains from the 1940-41 epidemic.
• Identified specific strains with distinct antigenic profiles, aiding in understanding viral evolution.