T-cell inactivation and immunosuppressive activity induced by HIV gp41 via novel interacting motif.

Fusion peptide (FP) of the HIV gp41 molecule inserts into the T cell membrane during virus-cell fusion. FP also blocks the TCR/CD3 interaction needed for antigen-triggered T cell activation. Here we used in vitro (fluorescence and immunoprecipitation), in vivo (T cell mediated autoimmune disease adjuvant arthritis), and in silico methods to identify the FP-TCR novel interaction motif: the alpha-helical transmembrane domain (TMD) of the TCR alpha chain, and the beta-sheet 5-13 region of the 16 N-terminal aa of FP (FP(1-16)). Deciphering the molecular mechanism of the immunosuppressive activity of FP provides a new potential target to overcome the immunosuppressant activity of HIV, and in addition a tool for down-regulating immune mediated inflammation.