Blocking Antibodies in Rabbits Infected with Brucella melitensis.

Summary Six rabbits were infected intravenously with a single massive dose of Br. melitensis. Three were treated by subcutaneous administration of streptomycin and tetracycline for 2 weeks and 3 were left untreated. The untreated rabbits developed a markedly increased gamma globulin content in their serum, which was not appreciably changed by absorption with killed whole Br. abortus cells. In addition, the blocking phenomenon was demonstrated in low titers in serum of these rabbits by 29th day of infection. Antibiotic therapy was effective in preventing the rise of gamma globulins and of blocking antibody through the 59th day.