Efficacy of immune sera from human immunoglobulin transgenic mice immunized with a peptide mimotope of Cryptococcus neoformans glucuronoxylomannan

Robert W. Maitta, Kausik Datta, Liise Anne Pirofski

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19 Scopus citations


The efficacy of antibody mediated immunity against Cryptococcus neoformans has not been established experimentally for human antibodies. Our group has previously shown that immunization with a conjugate consisting of a peptide mimotope of the C. neoformans capsular polysaccharide glucuronoxylomannan (GXM), P13, and diphtheria toxoid (P13-DT) prolonged survival of transgenic mice with human immunoglobulin loci, XenoMouse® mice, which were challenged with a lethal dose of C. neoformans. In the study reported herein, we determined the efficacy of human antibodies in the sera of immunized XenoMouse® mice against C. neoformans in passive transfer experiments in naïve BALB/c mice. Survival studies were performed with sera from XenoMouse® mice expressing human IgG2/kappa (G2/k mice) or IgG4/kappa (G4/k mice) that had been immunized with P13-tetanus toxoid (TT)/Alhydrogel with or without CpG, and G2/k mice that had been immunized with P13-DT/Alhydrogel/CpG or Alhydrogel/CpG, obtained on day 7 (early sera) and days 30 or 35-59 (late sera) after primary immunization. Compared to mice receiving sera from G2/k-PBS-treated mice, the survival of naïve mice was prolonged by both early and late sera from G2/k-P13-DT/Alhydrogel/CpG-immunized mice, but only late sera from G2/k-P13-TT/Alhydrogel/CpG-immunized mice. Late, but not early sera from G2/k-Alhydrogel/CpG-immunized mice also prolonged survival. For all sera, prolongation of survival was associated with GXM-specific serum IgM. Sera from G2/k mice that received P13-TT without CpG, and all groups of G4/k mice had low to undetectable levels of antibody to GXM and were not protective. Our findings suggest that GXM-specific human IgM may be a functional mediator of protection against C. neoformans.

Original languageEnglish (US)
Pages (from-to)4062-4068
Number of pages7
Issue number29-30
StatePublished - Sep 28 2004


  • Antibody-mediated immunity
  • Cryptococcus neoformans
  • Mimotope vaccine

ASJC Scopus subject areas

  • Molecular Medicine
  • Immunology and Microbiology(all)
  • veterinary(all)
  • Public Health, Environmental and Occupational Health
  • Infectious Diseases

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