In a vaccine model, selected substitution of a highly stimulatory T cell epitope of hen's egg lysozyme into a Salmonella flagellin does not result in a homologous, specific, cellular immune response and may alter the way in which the total antigen is processed.

A 13 amino acid peptide corresponding to a potent BALB/c mouse T cell epitope of hen's egg lysozyme (HEL) was substituted singly at five sites in the d flagellin of Salmonella muenchen. The resulting chimeric proteins were unable to expand T cells capable of being stimulated by the HEL epitope and induced T cell populations which either failed to respond or responded at a low level to a normally highly stimulatory flagellin T cell epitope that was present in all chimeras. The results suggested that substitution of a T cell epitope in flagellin may alter the processing of the resulting immunogen.