A composition as disclosed is comprised of a plurality of groups of particles. The particles are comprised of a biocompatible polymer which may be a co-polymer such as PLGA combined with a peptide of a sequence of interest, e.g. a sequence which corresponds to a sequence presented on a surface of a cell infected with a virus. A plurality of different groups of particles are provided in the formulation wherein the particles within any single group include peptides of identical amino acid sequence. The particles are sized such that they are sufficiently large so as to prevent more than the contents of a single particle from being presented to a single immune system cell.