CASEOUS LYMPHADENITIS IN SMALL RUMINANTS: CLINICAL, PATHOLOGICAL, AND IMMUNOLOGICAL RESPONSES TO CORYNEBACTERIUM PSEUDOTUBERCULOSIS AND TO FRACTIONS AND TOXINS FROM THE MICROORGANISM

Corynebacterium pseudotuberculosis is the etiologic agent of caseous lymphadenitis, a chronic, debilitating disease of small ruminants characterized by suppurative infection of either or both lymph nodes and visceral organs. Several antigenic constituents and virulence factors of the microorganism were studied.;In vitro interactions of caprine complement, antiserum, and leukocytes with intact and lipid depleted C pseudotuberculosis were studied. Regardless of host defense components present in the bactericidal test systems there was no dramatic killing effect exerted on either intact or lipid depleted microorganisms. Complement, antiserum, and leukocyte mixtures were best able to control bacterial growth. Mixtures containing complement, leukocytes and untreated organisms yielded the most dramatic growth of bacteria with the leukocytes apparently serving as a nutrient source promoting bacterial growth.;Experimental vaccines including preparations containing toxoid-aluminum hydroxide, bacterin-aluminum hydroxide and an oil-in-water emulsion containing P3 trehalose dimycolate with sonicate antigen and the adjuvants alone were given to 6 groups of animals. Subsequently, all the animals were challenge exposed to 10('7) live organisms on post vaccination day (PVD) 98. Delayed-type hypersensitivity skin tests were conducted with toxoid, purified protein derivative-like antigen, sonicate antigen, and autoclaved sonicate antigen on PVD 85, 167, and 262, and to cell wall antigen on 262. The vaccines did not protect against challenge. Sonicate, autoclaved sonicate and cell wall antigens hold promise as skin test reagents, whereas, the sonicate and cell wall antigens were unsatisfactory for assessing caprine humoral immune response to C pseudotuberculosis using an enzyme-linked immunosorbent assay.;The exotoxin produced by C pseudotuberculosis was highly toxic to gnotobiotic small ruminants. Animals receiving live organisms, cultural supernatant, and ion-exchange purified exotoxin preparations commonly developed a number of pathophysiologic changes including severe hemolytic anemia with hemoglobinuria, icterus, dark red colored fluid in body cavities, pulmonary edema, and hemorrhage and edema at the site of infection. Gnotobiotes inoculated with ammonium sulfate fractionated crude exotoxin containing high levels of exotoxin developed an acute shock syndrome. The exotoxin possessed a sphingomyelin-specific phospholipase D activity, and had a molecular weight of 31,000, and a pI of approximately 9.6.