IE1-pp65 recombinant protein from human CMV combined with a nanoparticulate carrier, SMBV, as a potential source for the development of anti-human CMV adoptive immunotherapy

Background Human cytomegalovirus (HCMV) infection and reactivation following allogeneic bone marrow transplantation is a major source of complications in grafted patients including pneumonitis, graft rejection and even death. Adoptive immunotherapy consisting in transfer of CD4 + and CD8 + T cells directed against HCMV has proved its worth. Nevertheless, established procedures have to be improved in terms of safety and waiting period required to obtain specific T cells. Methods As an alternative to infectious virus used in current strategies, we purified a recombinant protein IE1–pp65 resulting from the fusion of the regulatory IE1 and matrix pp65 proteins, both known as the major targets of the overall anti-HCMV T cell response. Based on our previous data demonstrating its use for in vitro stimulation and expansion of anti-HCMV CD4 + and CD8 + T cells (Vaz-Santiago et al, 2001, J.Virol, 75:7840–47) from peripheral blood mononuclear cells (PBMC) of seropositive donors, we planned to improve its in vitro immunogenicity through association with a nanoparticulate carrier, SMBVTM. Results We demonstrated that using of SMBV™/IE1–pp65 formulation allowed to potentiate in vitro activation of T cells and to expand more CD81 T cells than with soluble IE1–pp65, following stimulation of PBMC. Discussion These data suggest the use of SMBVTM/IE1–pp65 formulation as a potential source of antigen for efficient T cells expansion in the development of safe anti-HCMV immunotherapy.