Characterization of major surface glycoprotein genes of human Pneumocystis carinii and high-level expression of a conserved region.
To facilitate studies of Pneumocystis carinii infection in humans, we undertook to better characterize and to express the major surface glycoprotein (MSG) of human P. carinii, an important protein in host-pathogen interactions. Seven MSG genes were cloned from a single isolate by PCR or genomic library screening and were sequenced. The predicted proteins, like rat MSGs, were closely related but unique variants, with a high level of conservation among cysteine residues. A conserved immunodominant region (of approximately 100 amino acids) near the carboxy terminus was expressed at high levels in Escherichia coli and used in Western blot studies. All 49 of the serum samples, which were taken from healthy controls as well as from patients with and without P. carinii pneumonia, were reactive with this peptide by Western blotting, supporting the hypothesis that most adult humans have been infected with P. carinii at some point. This recombinant MSG fragment, which is the first human P. carinii antigen available in large quantities, may be a useful reagent for investigating the epidemiology of P. carinii infection in humans.
Critical Care Medicine Department, Clinical Center, National Institutes of Health, Bethesda, Maryland 20892, USA.
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D017088:AIDS-Related Opportunistic Infections / Q000097:blood / Q000276:immunology / Q000382:microbiology*; D000328:Adult; D000595:Amino Acid Sequence; D000818:Animals; D000908:Antibodies, Fungal / Q000097:blood / Q000276:immunology; D000946:Antigens, Fungal / Q000235:genetics* / Q000276:immunology; D001483:Base Sequence; D002460:Cell Line; D003001:Cloning, Molecular; D017124:Conserved Sequence; D004271:DNA, Fungal; D005656:Fungal Proteins / Q000235:genetics* / Q000276:immunology; D015870:Gene Expression; D005800:Genes, Fungal; D014644:Genetic Variation; D006801:Humans; D008562:Membrane Glycoproteins / Q000235:genetics* / Q000276:immunology; D008969:Molecular Sequence Data; D011010:Pneumocystis / Q000235:genetics* / Q000276:immunology; D011020:Pneumonia, Pneumocystis / Q000097:blood / Q000276:immunology / Q000382:microbiology*; D011993:Recombinant Fusion Proteins / Q000235:genetics / Q000276:immunology; D017386:Sequence Homology, Amino Acid; D018411:Spodoptera
D000908:Antibodies, Fungal; D000946:Antigens, Fungal; D004271:DNA, Fungal; D005656:Fungal Proteins; D008562:Membrane Glycoproteins; D011993:Recombinant Fusion Proteins; C077556:GPA protein, Pneumocystis carinii sp.