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Coronavirus pseudoparticles formed with recombinant M and E proteins induce alpha interferon synthesis by leukocytes
P Baudoux1, C Carrat, L Besnardeau
1Unité de Virologie Immunologie Moléculaires, INRA, 78350 Jouy-en-Josas, France.
Journal of Virology
|October 10, 1998
Summary
Transmissible gastroenteritis virus (TGEV) induces alpha interferon (IFN-alpha) via its M protein. This study shows that M protein, potentially in a multimeric structure, is key for IFN-alpha induction, not viral spikes or ribonucleoprotein.
Area of Science:
- Virology
- Immunology
Background:
- Transmissible gastroenteritis virus (TGEV) is a swine enteric coronavirus.
- TGEV is a potent inducer of alpha interferon (IFN-alpha) in vivo and in vitro.
- Previous studies implicated the viral membrane glycoprotein M in TGEV-induced IFN-alpha synthesis.
Purpose of the Study:
- To investigate the role of the TGEV M protein in IFN-alpha induction.
- To determine if other TGEV structural proteins are necessary for M protein's interferogenic activity.
Main Methods:
- Recombinant M protein was expressed in cells, alone and with other TGEV structural proteins.
- Cells coexpressing M and E proteins were analyzed for IFN-alpha induction.
- Pseudoparticles and chimeric particles were generated and their IFN-alpha-inducing activity was assessed.
Main Results:
- Cells coexpressing M and E proteins induced IFN-alpha similarly to TGEV-infected cells.
- Purified pseudoparticles containing M and E proteins showed IFN-alpha-inducing activity comparable to TGEV virions.
- Chimeric particles with modified M protein and bovine coronavirus (BCV) pseudoparticles retained interferogenic activity.
Conclusions:
- The TGEV M protein is essential for IFN-alpha induction.
- Neither ribonucleoprotein nor spikes are required for IFN-alpha induction by coronavirus particles.
- The IFN-alpha-inducing capacity of coronaviruses likely relies on a specific multimeric structure of the M protein rather than a defined sequence motif.