Experimental infection of convalescent mice with Corynebacterium ovis

Abstract

Extract

An eaplier paper described disease caused by experimental infection of normal mice with Corynebacterium ovis (Jolly, 1965a). Local lesions developed at the site of infection while distribution of secondary lesions indicated a bacteraemic phase. Many organisms were filtered out in the liver and spleen, presumably by reticulo-endothelial cells. Organisms were able to multiply at these sites but in the spleen, and in a proportion of foci in the liver, were eventually controlled and eliminated. The earliest reaction to the organism was often histiocytic, these cells being apparently unable to kill the bacteria or inhibit their multiplication. An intense neutrophil reaction which often subsequently developed, particularly in the liver, tended to promote the development of an abscess that would have survival advantages for the organism. Lesions in the spleen and a proportion of lesions in the liver appeared to control infection about the sixth to eighth day post-infection about the sixth to eighth day post-infection by developing a lesion in which the predominating cell was a large macrophage with pale staining indistinct cytoplasm. Corynebacterium ovis is a facultative intracellular parasite. There is now abundant evidence to show that immunity to disease caused by certain organisms of this type is associated with populations of reticulo-endothelial cells which develop an enhanced ability to kill or inhibit multiplication of bacteria subsequent to infection of the host (Elberg, 1960; Mackaness, 1964b).