Abstract
Summary
The quantities of protein-bound and free serum sialic acid of calves experimentally infected with Anaplasma, a rickettsial parasite of erythrocytes of cattle, were ascertained at various phases of experimental infections. The percentage increase of free sialic acid in the sera of 4 calves, 2 of which were splenectomized, ranged between 25 and 150 while the bound sialic acid ranged from 6.3 and 41. In 2 splenectomized calves, the percentage increases of free sialic acid were 150 and 137 and the percentage increases of bound sialic acid were 41 and 15 respectively. In contrast, the percentage increases of free sialic acid in 2 nonsplenectomized calves were 25 and 46 and percentages of bound sialic acid in the same calves were 6.3 and 23 respectively. The percentage increase in free sialic acid was approximately the same regardless of the quantity of inoculum of infected blood, i.e., 5.0 ml or 220.0 ml, used. The maximal increase in free sialic acid occurred during the early invasive stage of the disease. The possibility that the free sialic acid in serum might have originated from the receptor substances of the erythrocytes is discussed in the light of a hypothesis concerning the cycle of development of the causative agent, according to which the invasive mechanism of Anaplasma involves penetration of the erythrocytic membrane by initial bodies of this organism.
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