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Mucosal immunity to influenza without IgA: an IgA knockout mouse model.
I N Mbawuike1, S Pacheco, C L Acuna
1Departments of Microbiology, Influenza Research Center, Respiratory Pathogens Research Unit, Baylor College of Medicine, Houston, TX 77030, USA. mbawuike@bcm.tmc.edu
Journal of Immunology (Baltimore, Md. : 1950)
|March 11, 1999
Summary
Immunoglobulin A (IgA) is not essential for preventing influenza virus infection in mice. While mucosal immunization can induce IgA, strategies stimulating other antibodies may offer broader protection against respiratory viruses.
Area of Science:
- Immunology
- Virology
- Respiratory Medicine
Background:
- Secretory Immunoglobulin A (sIgA) is a key antibody at mucosal surfaces, crucial for defending against respiratory pathogens.
- The specific role of IgA in protection against influenza virus infection and the efficacy of IgA-centric immunization strategies remain incompletely understood.
Purpose of the Study:
- To investigate the necessity of IgA in protection against influenza virus infection using IgA knockout (IgA-/-) mice.
- To evaluate the effectiveness of immunization strategies aimed at preferentially inducing secretory IgA for influenza protection.
Main Methods:
- Generation of IgA knockout (IgA-/-) mice and comparison with wild-type (IgA+/+) littermates.
- Aerosol challenge with influenza virus to assess pulmonary infection and mortality.
- Intranasal and intraperitoneal immunization with influenza vaccine and cholera toxin adjuvant to induce specific antibody responses (IgA, IgG, IgM).
Main Results:
- IgA-/- mice exhibited similar susceptibility to influenza virus infection, pulmonary replication, and mortality compared to IgA+/+ mice.
- Immunization successfully induced influenza-specific IgA in IgA+/+ mice but not IgA-/- mice, while IgG and IgM responses were comparable in both groups.
- Monoclonal antibodies of various isotypes (IgG1, IgG2a, IgM, polymeric IgA) demonstrated equal efficacy in preventing influenza infection in IgA-/- mice.
Conclusions:
- IgA is not required for the prevention of influenza virus infection and associated disease.
- While mucosal immunization can induce IgA, strategies that also stimulate other antibody classes (IgG, IgM) may be more beneficial for controlling influenza and other respiratory viral infections.