TRANSMISSIBLE FOWL LEUKOSIS 31 



(150) found that the intracutaneous inoculation of leukotic blood was no more 

 effective in inducing a state of immunity than were other modes of inoculation. 

 Jarmai, Stenszky, and Farkas (105) attempted to produce an active immunity 

 by injection of organ emulsion of the chick embryo without success. Chickens 

 which did not develop leukosis after receiving an inoculation of the agent-neutral- 

 izing plasma mixture succumbed to a later inoculation with leukosis agent alone, 

 indicating that a state of active immunity was not produced (Rothe Mever, 

 Engelbreth-Holm, and Uhl 174). 



Greppin (91) believed that he obtained some imnmnizing action with the use 

 of leukotic material that had been heated to 56° C. for from 20 to 40 minutes. 

 VVakamatsu (209) reported some experiments with the pure erythroblastic strain 

 of the Danish workers. He administered repeated intravenous doses of bile from 

 diseased birds and obtained, in birds so treated, some cfegree of protection to 

 subsequent inoculation with the active agent. Oberling and Guerin (143) in un- 

 published work found that, although bile would inactivate the agent of leukosis, 

 the mixture was without effect as an immunizing agent. 



Recently, Uhl (204) reported that he was able to secure same degree of active 

 immunity in chickens against the leukosis agent. His immunizing agent was 

 prepared b}- grinding the spleens of four chickens, diseased with the E-S strain 

 of agent, with the blood of these .same birds. The resultant mixture was sub- 

 jected to slow centrifugation followed by passage through an ultracentrifuge and 

 then diluted with two volumes of physiological salt solution. At this stage the 

 material was tested by animal inoculation and it was found that its activity was 

 decreased (one preparation produced the disease in only one of six birds into 

 which it was inoculated and another in three of six chickens). The material 

 was then mixed with Type C aluminum hydroxide in 2 percent solution and stored 

 at — 5° C. Ten hens and 11 chicks received a series of 12 subcutaneous injections 

 of the immunizing material over a period of two months, and one month after 

 the last immunizing injection all were given a test dose of active leukosis agent. 

 Two of the hens and four of the chicks developed leukosis. The remainder (eight 

 hens and seven chicks) were given three further inoculations with active agent, 

 which produced the disease in four of the hens and four of the chicks. The course 

 of the disease in these birds was somewhat longer than that in control, non- 

 immunized birds receiving a single inoculation of the active agent. The controls 

 consisted of a group of 10 chicks and 20 hens and all of the control group with the 

 exception of one chick died with leukosis. Plasma from seven of the immunized 

 birds was pooled and found to have a neutralizing action on the leukosis agent. 

 Uhl expressed the belief that the agent was bound to the aluminum hydroxide 

 and was liberated so slowly in the animal body that the majority of the birds 

 obtained sufficient stimulation to develop an immunity, but not enough agent 

 was liberated to produce the disease. 



RuffiUi (174 i) found that the leukosis agent in plasma was quickly destroyed 

 bj' bubbles of gaseous oxygen. A group of four animals that had received plasma 

 thus inactivated were given two inoculations of ground leukotic spleen 25 and 

 45 days after they had received the plasma without developing the disease. A 

 third inoculation with leukotic spleen caused leukosis in two of the chickens, 

 indicating the transient nature of the immunity produced (174 j). In another 

 experiment (174 j) ten chickens remained negative after receiving an injection 

 of the washing from a five-day-old culture of normal bone marrow in leukotic 

 plasma. After 35 days the group was inoculated with leukotic plasma and only 

 two developed leukosis, which he believes indicates some antigenic capacity of 

 the leukotic plasma after being used in the tissue culture. In another publication 



