Human CD4 T cell epitopes selective for Vaccinia versus Variola virus

Area of Science:

• Immunology
• Virology
• Bioinformatics

Background:

• Orthopoxvirus species share high sequence identity, leading to cross-reactive immune responses.
• Developing selective diagnostic tools for poxvirus infections is crucial due to cross-reactivity.

Purpose of the Study:

• Identify CD4 T cell epitopes conserved in Vaccinia virus (VACV) but absent in Variola virus (VARV).
• Discover immunogenic sequences for selective VACV identification and differential diagnosis of poxvirus infections.

Main Methods:

• In silico analysis of poxvirus genomes to identify conserved and unique peptide fragments.
• Evaluation of peptide recognition by VACV-specific T cell lines from healthy donors.
• Assessment of HLA-DR binding specificity and induction of peptide-specific CD4 T cell lines.

Main Results:

• Identified 12 CD4 T cell epitopes from B7R, B10R, and E7R proteins.
• Four peptides from B7R and B10R showed broad HLA-DR binding and induced T cell lines.
• Two B10R peptide sequences were absent in Monkeypox virus and mutated in Cowpox virus.

Conclusions:

• Identified VACV-specific CD4 T cell epitopes absent in VARV, aiding differential diagnosis.
• Demonstrated broad HLA-DR binding and T cell induction capacity of selected peptides.
• Highlighted the potential of identified epitopes for distinguishing between different poxvirus species.