Experimental production of anti-membrane bound variable surface glycoglycoprotein (anti-VSGm) antibodies for in vitro and in situ immunostaining of pathogenic African trypanosomes

Background: The variant surface glycoprotein (VSG) of the African trypanosomes is the major membrane protein of the plasma membrane of the bloodstream stage of the parasite. African trypanosomiasis (sleeping sickness in humans and nagana in animals) is caused by the systemic infection of the host by several sub-species of the extracellular haemoflagellate protozoa under genus Trypanosoma. As a defense barrier against the host immune response, the entire surface of the bloodstream form of trypanosome is covered with densely packed molecules of VSG that determines the antigenic phenotype of the parasite. Variant surface glycoprotein has a C-terminal domain that is highly conserved in various species of trypanosomes. Methods: The membrane bound VSG (VSGm) protein was prepared without denaturing the homologous region and by including numerous variable antigen types from Trypanosoma brucei brucei parasites. The purified VSGm native trypanosome protein was used to produce anti-VSGm immune sera in rabbits. The indirect immunofluorescence assay (IFA) was used to detect trypanosomes from mice blood, artificial culture media and cattle histological sections. Results: The resultant immune sera were able to detect different strains and species of African trypanosomes from in vivo and in situ sources after immunostaining. Anti-VSGm antibodies also demonstrated a unique property to locate trypanosomes within the histological tissues even after the trypanosome9s morphology had been distorted. Conclusion: The produced immune sera can be utilized for immunohistochemistry to detect Trypanosoma species in various fluids and tissues.