Abstract: The present invention provides a screening method for identifying a peptide capable of inducing a T cell response comprising: a) contacting a peptide having a level of identity with a sequence of a protein of a virus, with a test sample comprising T cells obtained from blood from a subject who is currently or has been recently infected with the virus, b) quantifying the response of the T cells to the peptide, c) comparing the T cells' response in b) to a response of a control sample comprising T cells obtained from blood from a subject who is not currently infected nor been recently infected with the virus, when contacted with the peptide, wherein a greater response to the peptide in b) than in c) is indicative of a peptide capable of inducing a T cell response.