Abstract
It seems tlaat equine infectious anaemia is specific to the horse, but some investigatorsreported the infectivity of this virus to man. For a long time we have been employed inthe production of various immune sera, using horses, and have thought II11lC[l on this subject.In 1955, we started the studies on hog cholera and a few other viruses througlr thetissue culture method, and some interesting results were obtained. Therefore, similar in-vestigations were also performed on the equine infectious anaemia virus.At the beginning of this investigation, the author could not find any available reportsin this field and therefore, found it to be very important to complete the cultivating methodfor equine tissue, since the horse seemed to be the only animal susceptible to this virus.Various experiments were performed, and the following results were obtained. lissuecultures were performed by the plasma-clotting method and the trypsin-dispersing method.l. Synthetic medium 199 containing various percentages of cattle serum was used asthe culture medium, and it was found that the optimal ratio of medium 199 and cattleserum was 7 : 3 (Table l), and in subsequent experiments the same ratio of medium 199and cattle serum was employed.2. As a fundamental experiment to determine, indirectly, the most adequate organsfor the cultivation, in young or adult horses, the tissue cultures from equine embryos at thelate stage of pregnancy were tried first because of the possibility of aseptic processing. Theresults were shown in Table 2. These results were not always consistently obtained, but inmy experiments the most excellent growth of tissue was obtained in the spleen, and goodgrowth was also obtained in the kidnies and the Nymph nodes. In the testis, lungs, andbone marrow, good growth was sometimes obtained, but in the liver and heart the resultswere not definite.3. If fresh tissue was used without delay, excellent growth was obtained in young oradult horses, as weI[ as in the embryos.4. Through the monolayer tissue culture meth studies regarding preservation methods, and the passage method of tissue culture, were under-taken by many investigators. In my experiments, the attempts at delaying the maximumcell-growth by rneans of placing the culture in the cold room and thus inhibiting its meta-bolism, were performed. The results were as excellent, or even better than in the experi-ments in which the tissue was cultivated after a long storage in the cold room. The cellsof horse origin wzere more easily grown, more adaptable to the acidified culture medium, and could be maintained longer tlnan the cells of swine origin. A few cultures of tissuederived from young horses were maintained for more than 100 days, in rny laboratory.Frorru the results described above, the author considers that a renaarkable outgrowth ofcells is obtainable not orxly in the spleen, kidnies and Nymph nodes of horses, but also inthe heart, liver, testis, muscle and bone marrow, if fresh organs are used and adequate cut-ture methods are applied, and, also, that these tissue cultures will be most suitable for usein investigations on the equine infectious anaemia virus.
