Protective effect of Nocardia rubra cell wall skeleton on experimental infection in normal and immunosuppressed mice

The protective effect of Nocardia rubra cell wall skeleton (N-CWS) on experimental infections was investigated in normal and immunosuppressed mice. Pretreatment with N-CWS provided protection against acute systemic infections due to Pseudomonas aeruginosa, Escherichia coli, Klebsiella pneumoniae, Serratia marcescens and Listeria monocytogenes in normal mice. N-CWS administered before or after challenge also showed protective activity against Herpes simplex virus infection in normal mice. N-CWS was the most effective against extracellular parasitic Pseudomonas aeruginosa infection when administered 1 day before challenge, but displayed the most potent protective activity against infection with Listeria monocytogenes, a facultative intracellular parasite, when administered 7 to 14 days before challenge. In mice with subcutaneous Pseudomonas aeruginosa infection, N-CWS suppressed abscess formation and decreased the viable cell count in the resultant abscess foci when administered either intraperitoneally or subcutaneously to the infected site. In addition, treatment with N-CWS markedly restored host defense ability against pseudomonal infection in mice immunosuppressed with cyclophosphamide, hydrocortisone and X-ray irradiation.