A method of determining a peptide domain necessary for an interaction between an envelope of a virus belonging to an HERV-W interference group and an hASCT receptor, the method comprising:
- identifying a nucleotide and/or peptide sequence of a precursor envelope of said virus,
- excluding a signal part of said sequence,
- detecting an amino acid motif having an amino acid sequence corresponding to SEQ ID No. 43, and
- excluding a C-terminus in the amino acid sequence between 15 and 25 amino acid positions after the amino acid motif having an amino acid sequence corresponding to SEQ ID No. 43.