부산대학교 도서관

Eight‐day‐old embryonated hen's eggs were used as a model to study Mycobacterium aviumvirulence. Strains isolated from human patients caused 20–90% mortality when eggs were infected by injection of bacterial suspensions into the amniotic sac. Virulence of examined strains subsequently decreased with passage through eggs to between 0 and 40% mortality in four passages. Virulence of the egg‐attenuated strains could be restored by passage through human peripheral blood mononuclear cells. The site of infection in the egg was usually the mesodermal layer of the chorioallantoic membrane. A few small granulomas containing acid‐fast bacteria were seen in the liver, but not in other organs. Death of chicken embryos may have resulted from destruction of the mesodermal layer of the chorioallantoic membrane with consequent respiratory failure. PBMCs infected with less virulent egg‐passaged strains of M. aviumproduced higher levels of tumor necrosis factor‐α than did peripheral blood mononuclear cells infected with more virulent nonpassaged strains.