Skip to main content
    • Aa
    • Aa

Toxoplasma gondii major surface antigen (SAG1): in vitro analysis of host cell binding

  • S. A. ROBINSON (a1), J. E. SMITH (a2) and P. A. MILLNER (a1)

Previous studies have indicated that SAG1, the major surface molecule of the protozoan parasite Toxoplasma gondii, is an important attachment ligand for the host cell. However, the research data that supports this claim comes largely from studies investigating tachyzoite binding, and not SAG1 binding per se. In this study we successfully developed an in vitro attachment assay to directly evaluate the mechanism of SAG1-host cell binding. Competition experiments were then performed using SAG1 that had been pre-treated with the neoglycoprotein BSA-glucosamide or with antibody. Soluble BSA-glucosamide blocked SAG1 attachment to MDBK cells in a dose-dependent manner, implying that SAG1 binding is mediated, in part, via attachment to host cell surface glucosamine. Interestingly, pre-incubation of SAG1 in polyclonal sera from chronically infected mice failed to block binding. This challenges the assumption that anti-SAG1 antibodies block parasite attachment through the masking of SAG1 host cell binding domains. Taken together, this evidence presents new strategies for understanding SAG1-mediated attachment.

Corresponding author
School of Biochemistry and Molecular Biology, University of Leeds, Leeds LS2 9JT, UK. Tel: +0113 343 3149. Fax: +0113 343 3167. E-mail:
Linked references
Hide All

This list contains references from the content that can be linked to their source. For a full set of references and notes please see the PDF or HTML where available.

BRECHT, S., CARRUTHERS, V. B., FERGUSON, D. J., GIDDINGS, O. K., WANG, G., JAKLE, U., HARPER, J. M., SIBLEY, L. D. & SOLDATI, D. (2001). The Toxoplasma micronemal protein MIC4 is an adhesin composed of six conserved apple domains. Journal of Biological Chemistry276, 41194127.

CARRUTHERS, V. B., HAKANSSON, S., GIDDINGS, O. K. & SIBLEY, L. D. (2000). Toxoplasma gondii uses sulfated proteoglycans for substrate and host cell attachment. Infection and Immunity68, 40054011.

DZIERSZINSKI, F., MORTUAIRE, M., CESBRON-DELAUW, M. F. & TOMAVO, S. (2000). Targeted disruption of the glycosylphosphatidylinositol-anchored surface antigen SAG3 gene in Toxoplasma gondii decreases host cell adhesion and drastically reduces virulence in mice. Molecular Microbiology37, 574582.

FOURMAUX, M. N., ACHBAROU, A. & MERCEREAU-PUIJALON, O., BIDERRE, C., BRICHE, I., LOYENS, A., ODBERG-FERRAGUT, C., CAMUS, D. & DUBREMETZ, J. F. (1996). The MIC1 microneme protein of Toxoplasma gondii contains a duplicated receptor-like domain and binds to host cell surface. Molecular and Biochemical Parasitology83, 201210.

GARCIA-RÉGUET, N., LEBRUN, M., FOURMAUX, M. N., MERCEREAU-PUIJALON, O., MANN, T., BECKERS, C. J., SAMYN, B., VAN BEEUMEN, J., BOUT, D. & DUBREMETZ, J. F. (2000). The microneme protein MIC3 of Toxoplasma gondii is a secretory adhesin that binds to both the surface of the host cells and the surface of the parasite. Cellular Microbiology2, 353364.

GRIMWOOD, J. & SMITH, J. E. (1992). Toxoplasma gondii: The role of a 30 kDa surface protein in host cell invasion. Experimental Parasitology74, 106111.

HEUKESHOVEN, J. & DERNICK, R. (1988). Improved silver staining procedure for fast staining in PhastSystem Development Unit. I. Staining of sodium dodecyl sulfate gels. Electrophoresis9, 2832.

JACQUET, A., COULON, L., DE NEVE, J., DAMINET, V., HAUMONT, M., GARCIA, L., BOLLEN, A., JURADO, M. & BIEMANS, R. (2001). The surface antigen SAG3 mediates the attachment of Toxoplasma gondii to cell-surface proteoglycans. Molecular and Biochemical Parasitology116, 3544.

LAEMMLI, U. K. (1970). Cleavage of structural proteins during the assembly of the head of bacteriophage T4. Nature, London227, 680685.

LOURENCO, E. V., PERIERA, S. R., FAÇA, V. M., COELHO-CASTELO, A. A. M., MINEO, J. R., ROQUE-BARREIRA, M.-C., GREENE, L. J. & CASTEOL-PANUNTO, A. (2001). Toxoplasma gondii micronemal protein MIC1 is a lactose-binding lectin. Glycobiology11, 541547.

LUFT, B. F. & REMINGTON, J. S. (1992). Toxoplasmic encephalitis in AIDS. Clinical Infection and Disease15, 211222.

MADIN, S. H. & DARBY, N. B. (1958). Established kidney cell lines of normal adult bovine and ovine origin. Proceedings of the Society of Experimental Biology and Medicine98, 574576.

MILLER, N. L., FRENKEL, J. K. & DUBEY, J. P. (1972). Oral infections with Toxoplasma cysts and oocysts in felines, other mammals, and in birds. Journal of Parasitology58, 928937.

MINEO, J. R. & KASPER, L. H. (1994). Attachment of Toxoplasma gondii to host cells involves major surface protein, SAG1-1 (P30). Experimental Parasitology79, 351361.

ORTEGA-BARRIA, E. & BOOTHROYD, J. C. (1999). A Toxoplasma lectin-like activity specific for sulfated polysaccharides is involved in host cell infection. Journal of Biological Chemistry274, 12671276.

REISS, M., VIEBIG, N., BRECHT, S., FOURMAUX, M-F., SOÈTE, M., DI CRISTINA, M., DUBREMETZ, J. F. & SOLDATI, D. (2001). Identification and characterisation of an escorter for two secretory adhesions in Toxoplasma gondii. Journal of Cell Biology152, 563578.

STRIEPEN, B., ZINECKER, C. F., DAMM, J. B. L., MELGERS, P. A., GERWIG, G. J., KOOLEN, M., VLIEGENTHART, J. F., DUBREMETZ, J. F. & SCHWARTZ, T. T. (1997). Structure of low molecular weight antigen of Toxoplasma gondii: a glucose alpha-1-4 N-actelgalactosamine makes free glycosyl-phosphatidylinositols highly immunogenic. Journal of Molecular Biology266, 797813.

TOWBIN, H., STAEHELIN, T. & GORDON, J. (1978). Electrophoretic transfer of proteins from polyacrylamide gels to nitrocellulose sheets: procedure and some applications. Proceedings of the National Academy of Sciences, USA76, 43504354.

Recommend this journal

Email your librarian or administrator to recommend adding this journal to your organisation's collection.

  • ISSN: 0031-1820
  • EISSN: 1469-8161
  • URL: /core/journals/parasitology
Please enter your name
Please enter a valid email address
Who would you like to send this to? *



Full text views

Total number of HTML views: 3
Total number of PDF views: 5 *
Loading metrics...

Abstract views

Total abstract views: 46 *
Loading metrics...

* Views captured on Cambridge Core between September 2016 - 28th May 2017. This data will be updated every 24 hours.