Immunogenicity of the Escherichia coli fimbrial antigen K99 when expressed by Salmonella enteritidis 11RX.

Salmonella strains expressing the Escherichia coli fimbrial protein K99 were used to immunize adult mice, and the resulting anti-K99 T-cell responses were examined. Immunized animals displayed delayed-type hypersensitivity responses when challenged with K99 in the footpad. Lymphoid cells from immunized animals proliferated and released cytokines when cultured in vitro with K99 or peptides generated by cyanogen bromide treatment; the T cells which responded had the CD4+ phenotype.