Written by Gizem Güler

The infectious disease influenza (also known as flu) is caused by the influenza virus, which is a single-stranded RNA virus belonging to the virus family Orthomyxoviridae. The communicable influenza viruses A, B and C are subdivided into various strains based on the antigenic surface molecules. Highly infectious droplets containing the virus are globally spread and affect 10-20 % of the world population. Influenza-associated pandemics return on a seasonal base and are considered to have the highest global death toll of all infectious diseases with 500 000 deaths per year. Severe or life-threatening illness is mainly reported in high-risk patients like elderly, young and immunosuppressed patients. Non-specific constitutional symptoms of the viral infection are likely to be associated with complications affecting mainly the respiratory tract like pneumonia. The rapidly evolving virus strains are a huge challenge in drug development due to mutational evading mechanisms like antigenic drift and shift. Even though many annual vaccines and anti-influenza agents are already used in clinics, influenza remains a focus in research, where more efficient targets are being investigated.

Clinical Features



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  1. "Stiver et al. The treatment of influenza with antiviral drugs. CMAJ. 2003 Jan 7; 168(1): 49–57."
  2. "Davies et al. Pharmacokinetics of oseltamivir: an oral antiviral for the treatment and prophylaxis of influenza in diverse populations. J Antimicrob Chemother. 2010 Apr; 65(Suppl 2): ii5–ii10."
  3. "Pinto, Lamb. The M2 Proton Channels of Influenza A and B Viruses. The Journal of Biological Chemistry 281, 8997-9000, April 7, 2006."
  4. "Lorenzo, Fenton. Immunobiology of Influenza Vaccines. Chest. 2013 Feb; 143(2): 502–510."
  5. "Sautto, Kirchenbaum et al. Towards a universal influenza vaccine: different approaches for one goal. Virol J. 2018; 15: 17."
  6. "Pleschka, Ludwig, Planz et al. Influenza virus propagation is impaired by inhibition of the Raf/MEK/ERK signalling cascade. Nature Cell Biology volume 3, pages 301–305 (2001)."
  7. "Planz. Development of cellular signaling pathway inhibitors as new antivirals against influenza. Antiviral Research, Volume 98, Issue 3, June 2013, Pages 457-468."
  8. "Cope, Ross et al. Characterising seasonal influenza epidemiology using primary care surveillance data. Plos. August 16, 2018."
  9. "Zheng, Tao. Structure and assembly of the influenza A virus ribonucleoprotein complex. FEBS Letters, Volume 587, Issue 8, 17 April 2013, Pages 1206-1214."
  10. "Treanor et al. Influenza Vaccine: Outmaneuvering Antigenic Shift and Drift. N Engl J Med 2004; 350:218-220."
  11. "Nicholson. Clinical features of influenza. Semin Respir Infec. 1992 Mar;7(1):26-37."
  12. "Racaniello. Pathogenesis of influenza in humans. Virology Blog (2009)."
  13. "Fukuyama et al. The pathogenesis of influenza virus infections: the contributions of virus and host factors. Curr Opin Immunol. 2011 Aug; 23(4): 481–486. "
  14. "Chen & Lui et al. Host Immune Response to Influenza A Virus Infection. Front Immunol. 2018; 9: 320."
  15. "Plant, Fredell et al. Different Repeat Annual Influenza Vaccinations Improve the Antibody Response to Drifted Influenza Strains. Scientific Reports volume 7, Article number: 5258 (2017)."
  16. "Banning M. Influenza: incidence, symptoms, treatment. Br J Nurs. 2005 Dec 8-2006 Jan 11;14(22):1192-7."
  17. "Taubenberger, Morens. The pathology of influenza virus infections. Annu Rev Pathol. 2008 Aug 11."
  18. "Bouvier, Palese. The biology of influenza viruses.Vaccine. 2011 Apr 12."
  19. "Das, Krug et al. Structures of influenza A proteins and insights into antiviral drug targets. Nat Struct Mol Biol. 2011 May 1."
  20. "Pulendran,Maddran. Innate immune sensing and response to influenza. Curr Top Microbiol Immunol. PMC 2015 Mar."
  21. "M Tafalla. A comprehensive review of the epidemiology and disease burden of Influenza B in 9 european countries. Hum Vaccin Immunother. 2016 Apr; 12(4): 993–1002."
  22. "Rothberg, Brown. Complications of viral influenza. Am J Med. 2008 Apr;121(4):258-64."