Polymorphonuclear leukocyte dysfunction during influenza virus infection in chinchillas

Area of Science:

• Immunology
• Virology
• Microbiology

Background:

• Chinchillas infected with Streptococcus pneumoniae and influenza A virus show increased susceptibility to pneumococcal otitis media.
• The mechanism by which influenza A virus infection enhances susceptibility to secondary bacterial infections requires further investigation.

Purpose of the Study:

• To investigate the effect of influenza A virus infection on polymorphonuclear leukocyte (PMNL) function in chinchillas.
• To determine if impaired PMNL function contributes to increased susceptibility to pneumococcal infections.

Main Methods:

• Thirty-four chinchillas were intranasally inoculated with either influenza A virus or sterile saline.
• Polymorphonuclear leukocyte (PMNL) function, including chemotactic, chemiluminescent, and bactericidal activities, was assessed before and after inoculation.
• Phagocytic activity of PMNLs was also evaluated.

Main Results:

• Influenza A virus infection significantly depressed PMNL chemotactic, chemiluminescent, and bactericidal activities between days 4 and 8 post-inoculation.
• Maximum reductions in PMNL function were observed on day 6: 37% for chemotaxis, 53% for chemiluminescence, and 26% for bactericidal activity.
• PMNL phagocytosis remained unaffected by the influenza A virus infection.

Conclusions:

• Influenza A virus infection impairs critical functions of polymorphonuclear leukocytes (PMNLs) in chinchillas.
• The observed deficits in PMNL chemotaxis and oxidative microbicidal activity likely contribute to the increased susceptibility to pneumococcal disease following influenza A virus infection.