Tissues of spleen, kidney, heart, liver, lung, and the inner coat of the aorta of equine fetus were cultured, under static, conditions, in culture medium No.199 containing 30 per cent bovine serum, by using the plasma-clot method. Strain No.142, which had been supplied by the National Institute of Animal Health, Ministry of Agriculture and Forestry, was inoculated to this culture and incubated at 37°C, passage being made through the same culture every 7 days. Recovery tests were performed by inoculating 10 and 30 cc of the viral material of the fifth generation into colts, 8 and 9 months old, respectively. As a result, pyrexia was observed only in the colt inoculated with 30cc of the viral material, on the 26th day postinoculation and the highest temperature, 40.2°C, was reached on the 28th day. The pyrexia lasted for 5 days. During this period, red blood cell count began to decrease and showed the lowest value, 4, 550, 000 on the 37th day, the initial value being about 9 million.
Besides, siderocytes made their first appearance about one week after removal of the fever and were observed for about 19 days, numbering 1.5 to 11.0 per 10, 000 leukocytes. From these findings, it was considered that the experimental colt had manifested clearly the symptoms characteristic of equine infectious anemia by the inoculation of cultured virus.
On the other hand, no recognizable results were given by recovery tests on colts inoculated with 60 cc each of cultured material of the eighth generation.
In addition, observation was made on cell response after the inoculation of virus, but no cellular changes were noted in short-time cultures during cultivation by passage. Even after the inoculation of virus, it was not rare to observe the multiplication of newborn cells. However, the results of observations made for 44 to 61 days indicate that the first appearance of such cellular changes as were easily detected at low-power magnification was definitely earlier in the inoculated group than the control and that the degree of such changes seemed to be higher usually in the inoculated group.
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