Published online by Cambridge University Press: 06 April 2009
A structure called ‘veil’ in Theileria sergenti-, T. buffeli- or T. orientalis-infected bovine erythrocytes was purified from erythrocyte lysates by Percoll density-gradient centrifugation. On electron microscopical examination, the veils consisted of electron-dense material showing a periodicity of striations and were not surrounded by membranes. Analyses of veil proteins by one- and two-dimensional polyacrylamide gel electrophoresis revealed that the veils contain haemoglobin and several other basic proteins of molecular weight ranging from 15·5 to 46 kDa. By comparing the protein patterns of the veil with those of purified piroplasms and uninfected bovine erythrocytes, these basic proteins appeared to be of parasite origin. It would appear likely that the veils formed by intra-erythrocytic precipitation of haemoglobin and proteins excreted by the parasites. Differences in veil constituents were found between T. sergenti, T. buffeli and T. orientalis.