The present invention relates to a non-human animal model non-responsive
to bacterial components such as lipoproteins/lipopeptides, peptidoglycans
and endotoxins, being useful to elucidate the function of TIRAP being an
adaptor protein of TLR family; a substance promoting or suppressing the
response to bacterial components using these non-human animal models
non-responsive to bacterial components; and a method for screening these
promoting or suppressing substances, or the like. TIRAP.sup.-/- mice
wherein the function of the TIRAP gene is deleted on its chromosome, are
generated, and it is confirmed that the responsiveness to ligands
recognized by TLR2 such as lipoproteins/lipopeptides and to ligands
recognized by TLR4 such as endotoxins is specifically impaired in the
TIRAP.sup.-/- mice.