Immunoinformatic discovery of potential cross-reactive T cell epitopes in the measles genome

T cells are key mediators of inflammatory processes that can be activated by pathogens and vaccines. Some vaccine antigens may encode T cell epitopes that can cross-react with either human or human microbiome epitopes, causing deviation of the T cell response, leading to beneficial or, possibly, detrimental effects. An immune response shift attributed to cross-reactive T memory cells is known as heterologous immunity. Identification of T cell epitopes contained in pathogens and their vaccines and comparison of these epitopes against human and microbial genomic datasets are important steps to ensure that adaptive immune responses elicited by a vaccine are both pathogenspecific and protective, but not cross-reactive against host or hostassociated epitopes. Here, we use immunoinformatic methods to identify putative HLA A2-restricted measles vaccine epitopes that are cross-conserved with autologous proteins and with commensal microbiota. 45% and 63% of putative epitopes identified within the measles genome share significant homology to the human genome and a subset of genomes of the human microbiome, respectively. This important new information suggests there is significant potential for T cell cross-reactivity that will require experimental confirmation. Copyright © 2011 ACM