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Influenza A virus M1 blocks the classical complement pathway through interacting with C1qA

Junjie Zhang1,2, Gang Li1,2, Xiaoling Liu3,1

  • 1Graduate University of Chinese Academy of Sciences, Beijing 100101, PR China.

The Journal of General Virology
|August 7, 2009
PubMed

Insights

Influenza A virus M1 protein binds to complement C1qA, inhibiting the host immune response. This interaction enhances viral propagation and reduces host survival, highlighting M1's role in immune evasion.

Area of Science:

  • Virology
  • Immunology
  • Structural Biology

Background:

  • Influenza A virus matrix protein (M1) is crucial for viral replication.
  • The host complement system is a key component of innate immunity against viral infections.

Purpose of the Study:

  • To investigate the interaction between influenza A virus M1 protein and the complement system.
  • To elucidate the role of M1-complement interaction in viral pathogenesis and immune evasion.

Main Methods:

  • In vitro binding assays to assess M1-C1qA interaction.
  • Functional assays including haemolysis inhibition and complement-mediated neutralization.
  • In vivo studies using a mouse model of influenza A infection.

Main Results:

  • Influenza A M1 protein directly binds to complement C1qA via its N-terminal domain.
  • M1 inhibits the classical complement pathway by blocking C1qA-IgG interaction and preventing haemolysis.
  • M1 confers resistance to complement-mediated viral neutralization in vitro.
  • Administration of M1 protein increases viral load in mouse lungs and reduces survival rates.

Conclusions:

  • Influenza A M1 protein actively subverts the host innate immune system by interacting with complement C1qA.
  • This interaction is a critical mechanism for viral immune evasion and pathogenesis.
  • Targeting M1-complement interactions could represent a novel therapeutic strategy against influenza A virus.

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