Protective immunity to systemic nocardiosis in mice immunized with cell extract antigens of Nocardia asteroides.

Mice immunized with crude cell extract antigens of Nocardia asteroides as well as its purified fraction F1 elicited significant levels of both humoral and cellular immune responses. These animals when challenged with 50% lethal dose of N. asteroides, two weeks after the complete immunization exhibited significant protection as seen by decreased mortality and viable counts compared to nonimmunized. The immunized animals were capable of clearing the infection much faster as compared to control. Cell extract antigens which were mainly protein in nature are thought to have a prime role in prevention and restriction of nocardial infection.