Diagnostic Microbiology & Infectious Disease
Volume 45, Issue 1 , Pages 45-52, January 2003

Igm recognition of recombinant Toxoplasma gondii antigens by sera of acutely or latently infected humans

  • Bob Meek

      Affiliations

    • Department of Molecular Immunology, the Netherlands Ophthalmic Research Institute, Amsterdam, The Netherlands
    • ,
  • Robert Jan Diepersloot

      Affiliations

    • Laboratory for Medical Microbiology, Diakonessen Hospital, Utrecht, The Netherlands
    • ,
  • Tom van Gool

      Affiliations

    • Department of Medical Microbiology, Section Parasitology, Academic Medical Center, Amsterdam, The Netherlands
    • ,
  • Dave Speijer

      Affiliations

    • Department of Biochemistry, University of Amsterdam, Amsterdam, The Netherlands
    • ,
  • Ron Peek

      Affiliations

    • Department of Molecular Immunology, the Netherlands Ophthalmic Research Institute, Amsterdam, The Netherlands
    • Corresponding Author InformationCorresponding author. Tel.: +31-20-5666101; fax: +31-20-5666121.

Received 29 April 2002; accepted 19 August 2002.

Abstract 

Clinical non-relevant (CNR) IgM specific for Toxoplasma gondii is responsible for false-positive results in commercially available IgM assays. Using IgM immunoblotting, it is possible to distinguish between IgM in sera of acutely infected (AI) patients and CNR IgM. Especially the combination of staining of a 55 and 30 kD antigen in T.gondii lysate proved useful in this respect. The 55 kD antigen was identified as Rop1, while the 30 kD antigen was confirmed to be Sag1. However, the use of recombinant antigens instead of lysates for diagnostic assays would improve reproducibility. IgM recognized recombinant Rop1, but most CNR sera also had low anti-Rop1 titers. Although purified native Sag1 separated AI and CNR sera very well on immunoblot, IgM did not recognize recombinant Sag1 at all. Clearly, it is difficult to produce a recombinant Sag1 that can be recognized by IgM. Recombinant Rop1 might be suitable as one of the recombinant antigens in an IgM immunoblot assay, but has to be combined with at least one other immunogenic antigen.

Keywords:  Human, Toxoplasma, IgM, Recombinant antigens, Sag1, Rop1, Gra2, Immunoblotting

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PII: S0732-8893(02)00476-5

doi:10.1016/S0732-8893(02)00476-5

Diagnostic Microbiology & Infectious Disease
Volume 45, Issue 1 , Pages 45-52, January 2003

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