Treatment with anti-C5a antibody improves the outcome of H7N9 virus infection in African green monkeys

Clin Infect Dis. 2015 Feb 15;60(4):586-95. doi: 10.1093/cid/ciu887. Epub 2014 Nov 27.


Background: Patients infected with influenza A(H7N9) virus present with acute lung injury (ALI) that is due to severe pneumonia and systemic inflammation. It is often fatal because there are few effective treatment options. Complement activation has been implicated in the pathogenesis of virus-induced lung injury; therefore, we investigated the effect of targeted complement inhibition on ALI induced by H7N9 virus infection.

Methods: A novel neutralizing specific antihuman C5a antibody (IFX-1) was used. This antibody blocked the ability of C5a to induce granulocytes to express CD11b while not affecting the ability of C5b to form the membrane attack complex. African green monkeys were inoculated with H7N9 virus and treated intravenously with IFX-1.

Results: The virus infection led to intense ALI and systemic inflammatory response syndrome (SIRS) in association with excessive complement activation. Anti-C5a treatment in H7N9-infected monkeys substantially attenuated ALI: It markedly reduced the lung histopathological injury and decreased the lung infiltration of macrophages and neutrophils. Moreover, the treatment decreased the intensity of SIRS; the body temperature changes were minimal and the plasma levels of inflammatory mediators were markedly reduced. The treatments also significantly decreased the virus titers in the infected lungs.

Conclusions: Antihuman C5a antibody treatment remarkably reduced the ALI and systemic inflammation induced by H7N9 virus infection. Complement inhibition may be a promising adjunctive therapy for severe viral pneumonia.

Keywords: African green monkey; H7N9; anti-C5a antibody; complement inhibition; lung injury.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Acute Lung Injury / immunology
  • Acute Lung Injury / pathology
  • Acute Lung Injury / therapy
  • Acute Lung Injury / virology
  • Animals
  • Antibodies, Neutralizing / therapeutic use*
  • Body Temperature
  • Chlorocebus aethiops / virology
  • Complement Activation
  • Complement C5a / antagonists & inhibitors*
  • Complement C5a / immunology*
  • Disease Models, Animal
  • Humans
  • Influenza A Virus, H7N9 Subtype* / isolation & purification
  • Influenza A Virus, H7N9 Subtype* / pathogenicity
  • Influenza, Human / immunology
  • Influenza, Human / pathology
  • Influenza, Human / therapy*
  • Influenza, Human / virology
  • Lung / pathology
  • Lung / virology
  • Macrophages, Alveolar / immunology
  • Neutrophils / immunology
  • Orthomyxoviridae Infections / immunology
  • Orthomyxoviridae Infections / pathology
  • Orthomyxoviridae Infections / therapy
  • Orthomyxoviridae Infections / virology
  • Pneumonia, Viral / immunology
  • Pneumonia, Viral / pathology
  • Pneumonia, Viral / therapy*
  • Pneumonia, Viral / virology
  • Systemic Inflammatory Response Syndrome / pathology
  • Systemic Inflammatory Response Syndrome / therapy
  • Systemic Inflammatory Response Syndrome / virology
  • Treatment Outcome
  • Viral Load


  • Antibodies, Neutralizing
  • Complement C5a