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Evaluation of T Follicular Helper Cells and Germinal Center Response During Influenza A Virus Infection in Mice
Published on: June 27, 2020
AN IMMUNOLOGICAL STUDY OF BACILLUS INFLUENZAE
1Laboratories of The Rockefeller Institute for Medical Research.
Abstract:
Influenza bacilli isolated from various pathological processes in man differ widely in pathogenic power for animals, especially rabbits. While the cultures derived from the leptomeninges and blood, and rarely from the pneumonic lung are pathogenic, those generally derived from the respiratory tract exhibit little or no virulence for rabbits. The two types of cultures as indicated by virulence for animals do not differ in kind, but only in degree, in relation to the serological tests of agglutination, complement deviation, and opsonification. The two types of cultures do, however, differ with respect to their ability to undergo autolysis. While the virulent cultures autolyze almost completely, yielding a turbid supernatant fluid and little sediment, the non-virulent cultures give rise to an abundant sediment and a clear supernatant fluid. The non-virulent cultures incite far less antibody production in rabbits. Hence, rabbits inoculated with non-virulent strains yield sera possessing low antibody content. Conversely, rabbits inoculated with virulent strains yield sera possessing a higher content of antibody. In keeping with and possibly because of the low antibody content of the sera of rabbits inoculated with the non-pathogenic strains, the rabbits so treated are not, as a rule, protected against subsequent inoculation with virulent strains. . Influenza bacilli therefore vary in pathogenic effect both for man and animals, but they are not distinguishable by means of serological reactions into different types. Apparently all influenza bacilli belong to one class or race irrespective of origin or virulence.
Insights
Influenza bacilli show varied virulence in humans and animals, but serological tests cannot distinguish types. Virulent strains autolyze differently and elicit stronger antibody responses in rabbits.
Area of Science:
- Microbiology
- Pathogenesis
- Immunology
Background:
- Influenza bacilli exhibit variable pathogenicity in humans and animal models.
- Understanding the differences between virulent and non-virulent strains is crucial for disease control.
Purpose of the Study:
- To investigate the differences in virulence, serological characteristics, and autolysis of influenza bacilli from various pathological sources.
- To assess the antibody response in rabbits inoculated with different strains and their protective immunity.
Main Methods:
- Isolation of influenza bacilli from human pathological samples.
- Assessment of animal pathogenicity, primarily in rabbits.
- Serological testing including agglutination, complement deviation, and opsonification.
- Evaluation of bacterial autolysis and antibody production in inoculated rabbits.
Main Results:
- Influenza bacilli strains varied significantly in their virulence for rabbits, with strains from leptomeninges and blood being more pathogenic than respiratory tract isolates.
- Despite virulence differences, serological tests (agglutination, complement deviation, opsonification) did not distinguish between virulent and non-virulent strains.
- Virulent strains showed nearly complete autolysis with turbid supernatant, while non-virulent strains produced abundant sediment and clear supernatant.
- Non-virulent strains induced lower antibody production in rabbits, resulting in sera with low antibody content and poor protection against subsequent virulent strain inoculation.
Conclusions:
- Influenza bacilli exhibit a spectrum of virulence but are serologically indistinguishable, suggesting a single class or race.
- Differences in autolysis and antibody response correlate with virulence but do not define distinct serological types.
- Animal models, like rabbits, can reveal virulence variations and immune responses, aiding in understanding influenza bacilli pathogenesis.
