Stimulating T cells with HHV6 (U54) peptide pool releases downstream cytokines and upregulates activation markers, enabling antigen-specific T cells to be detected or isolated for analysis. HHV6 (U54) peptide pool is a lyophilised mixture of 112 peptides from protein U54 of human herpesvirus 6B (HHV-6B; strain Z29), and consists of 15-mer peptides with 11-amino-acid overlaps that cover amino acids 1 to 459 on U54. U54 is a tegument transactivator and is suggested to be a homolog of the CMV UL82/83 (pp65/72K) protein (Isegawa et al.; Nicholas). In infected T cells, U54 has been shown to inhibit gene transcription of interleukin 2 (IL-2), the T cell growth factor, which likely contributes to viral persistence (Iampietro et al.). Viral peptide pools are useful for a broad range of applications, including vaccine development, immunological research, and diagnostic assay development.