Peptide Centric Vβ Specific Germline Contacts Shape a Specialist T Cell Response

Area of Science:

• Immunology
• Structural Biology
• Molecular Medicine

Background:

• Certain CD8 T cell responses are crucial for controlling infections, such as HIV elite control linked to HLA-B57.
• Understanding the structural basis of these effective T cell responses is key to developing new therapies.

Purpose of the Study:

• To investigate the structural features of a highly protective CD8 T cell response targeting a parasite peptide (HF10) presented by the H-2Ld MHC-I molecule.
• To elucidate how specific T cell receptor (TCR) structures contribute to elite control of infection.

Main Methods:

• Structural analysis of a representative TCR (TG6) in complex with its peptide-MHC ligand (Ld-HF10).
• Examination of the TCR repertoire and its correlation with structural features.

Main Results:

• The study revealed an unusual TCR-pMHC structure where both TCR and MHC molecule significantly contribute to peptide specificity.
• A parallel footprint of the TCR on the pMHC ligand was observed, a characteristic of Vβ2-containing TCRs.
• This structural arrangement correlates with unique Vα-Vβ interfaces, CDR loop conformations, and Vβ2-specific germline contacts.

Conclusions:

• The Vβ2 T cell receptor and H-2Ld MHC-I molecule may act as specialized components for antigen recognition.
• These specialized components facilitate exceptionally strong and focused T cell responses, contributing to effective infection control.