Effects of treatment with muramyl dipeptide and certain of its analogs on resistance to Listeria monocytogenes in mice.

Studies were carried out to determine whether treatment of mice with the synthetic adjuvant muramyl dipeptide (MDP) afforded any resistance to infection with Listeria monocytogenes. Regardless of the timing, dose, or route of administration, there was no evidence that treatment with either MDP or two of its analogs (des-MDP or MDP-D-D) induced any resistance to listeria infection in BALB/c, CBA/J, or C57BL/6J mice. In contrast, pretreatment with MDP induced marked protection to infection with Streptococcus pneumoniae (type III).