Perspectives

Sialyltransferase activity probably counteracts that of sialidase as one of the possible mechanisms of natural recovery or stabilization of erythrocyte mass in trypanosome-infected animals - A perspective

Sani Adamu¹*, Najume D.G. Ibrahim¹, Andrew J. Nok² and King A.N. Esievo¹

¹Department of Veterinary Pathology and Microbiology, Faculty of Veterinary Medicine, Ahmadu Bello University, Zaria, Nigeria.

²Department of Biochemistry, Faculty of Science, Ahmadu Bello University, Zaria, Nigeria.

*Corresponding author. E-mail: sanad1966@yahoo.co.uk. Tel: +2348055696488.

Abbreviations: SD, Sialidase; SA, sialic acid; ST, sialyltransferase; Epo, erythropoietin.

Accepted 19 September, 2008

Attempts to unravel the mechanisms of development of anaemia in trypanosome-infected animals yielded varying reports with those that implicate trypanosomal sialidase (SD) being among those that enjoy prominence. Significant cleavage of sialic acid (SA) on erythrocyte membranes and terminal positions of erythropoietin (Epo) by SD, which is released during trypanosome infection of animals, results in their rapid clearance and destruction by cells of the mononuclear phagocytic system and in addition, in the case of Epo, decreased biologic activity of the hormone with consequent development of anaemia. Observations on free serum and erythrocyte surface SA profiles of trypanosome-infected animals suggest possible involvement of sialyltransferase (ST) in recovery or stabilization of red blood cell mass, which seems to be a probable explanation as to why some trypanosome-infected animals either recover from the anaemia or run a chronic infection with very low but stable erythrocyte mass. The speculated roles of ST open up a new and, probably, promising area of research; especially, if identification of mechanisms of natural resistance to trypanosome infection is of prime consideration in this contemporary period of research in molecular medicine.

Key words: Sialyltransferase, sialidase, sialic acid, erythropoietin, trypanosomosis, anaemia.