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Factors promoting pathogenicity of influenza virus
1Division of Pulmonary and Critical Care Medicine, University of Arkansas for Medical Sciences, Little Rock 72205.
Abstract:
Each year, influenza infections cause significant morbidity and mortality in spite of intense research and control efforts. Virus is transmitted primarily by aerosolization of respiratory secretions, and infection can be caused by a small number of viral particles. Following inhalation, virus is deposited on the mucous blanket overlying the target epithelial cell. Mucociliary clearance is the normal mechanism by which deposited particulates are removed; immunoglobulins at the airway surface also play an important role in neutralization of virus. Influenza virus is very efficient at overcoming host defenses, primarily due to the function of two surface glycoproteins, hemagglutinin and neuraminidase. Both glycoproteins have antigenic sites that undergo variation. Hemagglutinin also contains cell binding sites, while neuraminidase prevents interference of mucins with cell binding. Although other factors may contribute to infectivity of the influenza virus, antigenic variation of hemagglutinin is the single most important factor. Influenza vaccination is the most effective means presently available to decrease the attack rate and impact of this infection on society.
Insights
Influenza virus overcomes host defenses using hemagglutinin and neuraminidase surface glycoproteins. Antigenic variation in hemagglutinin is key to influenza
Area of Science:
- Virology
- Immunology
- Public Health
Background:
- Influenza infections cause substantial global morbidity and mortality annually.
- Transmission occurs via aerosolized respiratory secretions, requiring few viral particles for infection.
- Host defenses like mucociliary clearance and immunoglobulins are crucial but often insufficient.
Purpose of the Study:
- To elucidate the mechanisms by which influenza virus evades host defenses.
- To identify the key viral factors contributing to influenza infectivity and variation.
Main Methods:
- Analysis of influenza virus surface glycoproteins, hemagglutinin and neuraminidase.
- Examination of the role of antigenic variation in viral infectivity.
- Review of host defense mechanisms against influenza virus.
Main Results:
- Influenza virus efficiently overcomes host defenses primarily through hemagglutinin and neuraminidase.
- Both glycoproteins exhibit antigenic variation, with hemagglutinin variation being the most critical factor for infectivity.
- Hemagglutinin facilitates cell binding, while neuraminidase prevents mucin interference.
Conclusions:
- Antigenic variation in hemagglutinin is the most significant factor in influenza virus infectivity.
- Influenza vaccination remains the most effective strategy to reduce disease incidence and societal impact.