Related Experiment Video
Updated: Jun 19, 2026
Modeling Dysplastic and Functional Lung Alveolar Repair after Influenza Infection
Published on: September 19, 2025
EXPERIMENTAL INFECTION WITH INFLUENZA A VIRUS IN MICE : THE INCREASE IN INTRAPULMONARY VIRUS AFTER INOCULATION AND
1Laboratories of the International Health Division of The Rockefeller Foundation, New York.
Abstract:
Following intranasal inoculation of influenza A virus (strain PR8) there is a rapid increase of the virus in the lungs which with large doses reaches a maximum within 24 hours. With smaller doses, although the proportional increase is greater, the maximum concentration is not reached until 48 hours following inoculation. If a lethal dose is administered, the ultimate concentration of the virus in the lungs is the same, irrespective of the size of the dose. If a sublethal dose is given, the titer of the virus in the lungs does not achieve the titer reached in mice receiving a lethal dose. Within 48 hours following inoculation of a sublethal dose the lungs of a mouse may contain at least 76,000 M.L.D., yet the mouse survives. The intranasal instillation of sterile fluid (distilled water, varying concentrations of NaCl, broth, or 10 per cent normal serum) into a mouse sublethally infected produces a sharp rise in the virus content of the lung usually followed by death within 3 to 8 days. If, however, the instillate consists of 10 per cent immune serum, there is no rise in the virus titer, and no apparent harm results from the instillation. The implications of these phenomena are discussed and an hypothesis presented to explain their occurrence.
Insights
Intranasal influenza A virus (PR8) infection in mice shows dose-dependent lung viral loads. Sterile fluid instillation in sublethally infected mice increases viral load and causes death, while immune serum prevents this.
Area of Science:
- Virology
- Immunology
- Infectious Diseases
Background:
- Influenza A virus (IAV) infection is a significant global health concern.
- Understanding viral kinetics and host response is crucial for developing effective treatments.
- Previous studies have explored IAV replication dynamics in the respiratory tract.
Purpose of the Study:
- To investigate the impact of different influenza A virus (PR8 strain) doses on lung viral concentrations in mice.
- To determine the effect of intranasal instillation of various substances on the outcome of sublethal influenza infections.
- To explore potential mechanisms underlying observed phenomena in influenza virus infection.
Main Methods:
- Intranasal inoculation of mice with varying doses of influenza A virus (PR8).
- Quantification of lung virus titers at different time points post-infection.
- Intranasal instillation of sterile fluids (water, NaCl, broth, normal serum) or immune serum into sublethally infected mice.
- Monitoring survival rates and lung virus content following instillations.
Main Results:
- A rapid increase in lung virus concentration was observed post-inoculation, with peak levels dependent on the dose and time.
- Sublethal doses resulted in lower peak viral titers compared to lethal doses, yet mice survived.
- Instillation of sterile fluids into sublethally infected mice led to increased lung virus and mortality, whereas immune serum prevented this effect.
Conclusions:
- The dose of influenza A virus influences the kinetics of viral replication in the lungs.
- Sublethal infections can be exacerbated by non-specific intranasal instillation, suggesting a role for secondary factors.
- Immune serum confers protection against exacerbation of influenza infection, highlighting its therapeutic potential.
