The cloning and characterization of the arom gene of Pneumocystis carinii

ABSTRACT By using mouse models, it has been shown that Pneumocystis carinii f. sp. muris can be transmitted to immunocompetent mice that are exposed to immunosuppressed mice with active P. carinii pneumonia. We sought to determine whether P. carinii f. sp. muris could be transmitted between normal mice. The rationale for these experiments was to demonstrate whether the normal host could serve as the reservoir of organisms that produce Pcp when the organism is acquired by the immunosuppressed host. Under the conditions of these experiments, normal mice are able to be infected by brief cohousing with P. carinii-infected SCID mice. There was active replication of organisms in the normal host such that the organism could be transmitted to other normal mice, again with active replication. Mice that had seroconverted after exposure to P. carinii-infected SCID mice were more resistant to infection when reexposed. Infection in normal mice was well tolerated with minimal effects on dynamic lung compliance. We speculate, based on these results, that transmission from normal host to normal host, as an asymptomatic or minimally symptomatic infection, could be a way to maintain this opportunistic pathogen in the environment.

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A 55 kDa Antigen of Pneumocystis carinii: Analysis of the cellular immune response and characterization of the gene

Parasitology Today ◽

10.1016/0169-4758(93)90005-z ◽

1993 ◽

Vol 9 (6) ◽

pp. 199

Keyword(s):

Immune Response ◽

Cellular Immune Response ◽

Pneumocystis Carinii ◽

Cellular Immune

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Molecular Characterization of Recombinant Pneumocystis carinii Topoisomerase I: Differential Interactions with Human Topoisomerase I Poisons and Pentamidine

Antimicrobial Agents and Chemotherapy ◽

10.1128/aac.46.7.2145-2154.2002 ◽

2002 ◽

Vol 46 (7) ◽

pp. 2145-2154 ◽

Cited By ~ 6

Author(s):

Rukiyah T. Van Dross ◽

Marilyn M. Sanders

Keyword(s):

Topoisomerase I ◽

Pneumocystis Carinii ◽

Minor Groove Binding ◽

Groove Binding ◽

Hoechst 33342 ◽

Cytotoxicity Assays ◽

Fungal Enzyme ◽

Human Enzyme ◽

Encoding Gene

ABSTRACT The Pneumocystis carinii topoisomerase I-encoding gene has been cloned and sequenced, and the expressed enzyme interactions with several classes of topoisomerase I poisons have been characterized. The P. carinii topoisomerase I protein contains 763 amino acids and has a molecular mass of ca. 90 kDa. The expressed enzyme relaxes supercoiled DNA to completion and has no Mg2+ requirement. Cleavage assays reveal that both the human and P. carinii enzymes form covalent complexes in the presence of camptothecin, Hoechst 33342, and the terbenzimidazole QS-II-48. As with the human enzyme, no cleavage is stimulated in the presence of 4′,6′-diamidino-2-phenylindole (DAPI) or berenil. A yeast cytotoxicity assay shows that P. carinii topoisomerase I is also a cytotoxic target for the mixed intercalative plus minor-groove binding drug nogalamycin. In contrast to the human enzyme, P. carinii topoisomerase I is resistant to both nitidine and potent protoberberine human topoisomerase I poisons. The differences in the sensitivities of P. carinii and human topoisomerase I to various topoisomerase I poisons support the use of the fungal enzyme as a molecular target for drug development. Additionally, we have characterized the interaction of pentamidine with P. carinii topoisomerase I. We show, by catalytic inhibition, cleavage, and yeast cytotoxicity assays, that pentamidine does not target topoisomerase I.

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Characterization of Major Surface Glycoprotein Genes of Human Pneumocystis carinii and High-Level Expression of a Conserved Region

Infection and Immunity ◽

10.1128/iai.66.9.4268-4273.1998 ◽

1998 ◽

Vol 66 (9) ◽

pp. 4268-4273 ◽

Cited By ~ 33

Author(s):

Qin Mei ◽

Ross E. Turner ◽

Vivian Sorial ◽

Diane Klivington ◽

C. William Angus ◽

...

Keyword(s):

Genomic Library ◽

Pneumocystis Carinii ◽

Surface Glycoprotein ◽

High Level Expression ◽

Serum Samples ◽

Major Surface Glycoprotein ◽

Adult Humans ◽

Major Surface ◽

High Level

ABSTRACT To facilitate studies of Pneumocystis cariniiinfection 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 withoutP. 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. cariniiinfection in humans.

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