The Role of Viral, Host, and Secondary Bacterial Factors in Influenza Pathogenesis
The American Journal of Pathology, Vol. 185, No. 6, June 2015 ajp.amjpathol.org Infectious Disease Theme Issue REVIEW The Role of Viral, Host, and Secondary Bacterial Factors in Influenza Pathogenesis John C. Kash and Jeffery K. Taubenberger From the Viral Pathogenesis and Evolution Section, Laboratory of Infectious Diseases, National Institute of Allergy and Infectious Diseases, National Institutes of Health, Bethesda, Maryland Accepted for publication August 19, 2014. Influenza A virus infections in humans generally cause self-limited infections, but can result in severe disease, secondary bacterial pneumonias, and death. Influenza viruses can replicate in epithelial cells Address correspondence to Jeffery K. Taubenberger, M.D., throughout the respiratory tree and can cause tracheitis, bronchitis, bronchiolitis, diffuse alveolar damage fl Ph.D., Viral Pathogenesis and with pulmonary edema and hemorrhage, and interstitial and airspace in ammation. The mechanisms by Evolution Section, Laboratory which influenza infections result in enhanced disease, including development of pneumonia and acute of Infectious Diseases, National respiratory distress, are multifactorial, involving host, viral, and bacterial factors. Host factors that Institute of Allergy and Infec- enhance risk of severe influenza disease include underlying comorbidities, such as cardiac and respiratory tious Diseases, NIH, 33 North disease, immunosuppression, and pregnancy. Viral parameters enhancing disease risk include polymerase Dr, Room 3E19A.2, MSC mutations associated with host switch and adaptation, viral proteins that modulate immune and antiviral 3203, Bethesda, MD 20892- responses, and virulence factors that increase disease severity, which can be especially prominent in 3203. E-mail: taubenbergerj@ pandemic viruses and some zoonotic influenza viruses causing human infections. Influenza viral infections niaid.nih.gov.
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