Chapter

Cellular Peptidases in Immune Functions and Diseases

Volume 421 of the series Advances in Experimental Medicine and Biology pp 185-192

HIV-1 Envelope gp120 and Viral Particles Block Adenosine Deaminase Binding to Human CD26

  • Agustin ValenzuelaAffiliated withDepartament de Bioquímica i Biologia Molecular Facultad de Química, Universidad de Barcelona
  • , Julià BlancoAffiliated withUnité de Virologie et d’Immunologie, Cellulaire UA CNRS 1157, Institut Pasteur
  • , Christian CallebautAffiliated withUnité de Virologie et d’Immunologie, Cellulaire UA CNRS 1157, Institut Pasteur
  • , Etienne JacototAffiliated withUnité de Virologie et d’Immunologie, Cellulaire UA CNRS 1157, Institut Pasteur
  • , Carmen LluisAffiliated withDepartament de Bioquímica i Biologia Molecular Facultad de Química, Universidad de Barcelona
  • , Ara G. HovanessianAffiliated withUnité de Virologie et d’Immunologie, Cellulaire UA CNRS 1157, Institut Pasteur
  • , Rafael FrancoAffiliated withDepartament de Bioquímica i Biologia Molecular Facultad de Química, Universidad de Barcelona Email author 

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Abstract

CD26, known to be the adenosine deaminase (ADA) binding protein, has been implicated in HIV infection. In human B and T cell lines we show that, irrespective of CD4 expression, 125I-labeled ADA binding to CD26 is inhibited by recombinant soluble HIV-1 envelope glycoprotein gp120 and by HIV-1 infectious particles. Overlapping synthetic peptides covering the entire gp120 sequence were tested to map the region in gp120 responsible for ADA binding inhibition. Only peptides in the C3 region significantly inhibited the binding of ADA to CD26. These results indicate that a specific function of gp120 is the inhibition of ADA binding to CD26 in both CD4+ and CD4 cells. Since the interaction ecto-ADA/CD26 is required for the activation of T cells, it remains possible that HIV particle-mediated blockade of ecto-ADA/CD26 interaction may have significant consequences in the pathogenesis of AIDS disease.