RESUMO
Autoclaved cercarial vaccine (ACV) was found to be highly effective in eliciting protective immunity against experimental Schistosomal mansoni. So, the aim of this study was to analyse ACV biochemically and to study ultrastructural changes inflicted on the cercariae as a result of autoclaving, thus rendering it highly protective. Results of this study showed that approximately 100 microg protein and 44 microg carbohydrate were obtained from 10(3) cercariae. The predominant sugar was fucose. Galactose, glucose, manose, galactosamine and glucosamine were also detected. Threonine, glycine, serine and glutamic acid comprised approximately 53.7% of the amino acid residues of the protein. Ultrastructural study revealed preserved architecture of the cercariae. The tails were still attached to the posterior ends of the bodies. However, in others the tails were separated from the bodies and appear schistosomula like. There were also some morphological changes such as thinning of the pericortical envelop with appearance of surface pores.