Immunohistochemical study of the cyst of Besnoitia besnoiti

The present study has been undertaken in order to provide information on th e molecular structure of the cysts of Besnoitia besnoiti. To that end, immu nohistochemical techniques have been used to investigate the expression of several enzymes and proteins implicated in the cellular membrane permeabili ty of bradyzoites. Paraffin and frozen sections, which were obtained from s ubcutaneous tissue samples taken from naturally infected cattle (coming fro m northeast Spain), were treated with a panel of antibodies. These were spe cific for Na+, K+-ATPase, alkaline phosphatase, calmodulin, S100 protein, h eat shock proteins, hsp60, and hsp70. Positive-cysts for the said antibodie s were found in 23.3% of the cows studied. Bradyzoites showed a positive im munoreaction in every positive cyst with respect to all these antibodies. I n addition to the low percentage of positive animals, it is worth noting th at positive and unstained cysts were observed in the same tissue section. T hese results suggest that bradyzoites may pass through both active and dorm ant metabolic phases. (C) 2000 Elsevier Science B.V. All rights reserved.