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Cissé OH, Hauser PM. Genomics and evolution of Pneumocystis species. INFECTION GENETICS AND EVOLUTION 2018; 65:308-320. [PMID: 30138710 DOI: 10.1016/j.meegid.2018.08.015] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/30/2018] [Revised: 08/15/2018] [Accepted: 08/17/2018] [Indexed: 01/20/2023]
Abstract
The genus Pneumocystis comprises highly diversified fungal species that cause severe pneumonia in individuals with a deficient immune system. These fungi infect exclusively mammals and present a strict host species specificity. These species have co-diverged with their hosts for long periods of time (> 100 MYA). Details of their biology and evolution are fragmentary mainly because of a lack of an established long-term culture system. Recent genomic advances have unlocked new areas of research and allow new hypotheses to be tested. We review here new findings of the genomic studies in relation with the evolutionary trajectory of these fungi and discuss the impact of genomic data analysis in the context of the population genetics. The combination of slow genome decay and limited expansion of specific gene families and introns reflect intimate interactions of these species with their hosts. The evolutionary adaptation of these organisms is profoundly influenced by their population structure, which in turn is determined by intrinsic features such as their self-fertilizing mating system, high host specificity, long generation times, and transmission mode. Essential key questions concerning their adaptation and speciation remain to be answered. The next cornerstone will consist in the establishment of a long-term culture system and genetic manipulation that should allow unravelling the driving forces of Pneumocystis species evolution.
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Affiliation(s)
- Ousmane H Cissé
- Critical Care Medicine Department, NIH Clinical Center, National Institutes of Health, Bethesda, MD 20892, USA.
| | - Philippe M Hauser
- Institute of Microbiology, Lausanne University Hospital, Lausanne, Switzerland.
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2
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Ma L, Cissé OH, Kovacs JA. A Molecular Window into the Biology and Epidemiology of Pneumocystis spp. Clin Microbiol Rev 2018; 31:e00009-18. [PMID: 29899010 PMCID: PMC6056843 DOI: 10.1128/cmr.00009-18] [Citation(s) in RCA: 41] [Impact Index Per Article: 6.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/29/2022] Open
Abstract
Pneumocystis, a unique atypical fungus with an elusive lifestyle, has had an important medical history. It came to prominence as an opportunistic pathogen that not only can cause life-threatening pneumonia in patients with HIV infection and other immunodeficiencies but also can colonize the lungs of healthy individuals from a very early age. The genus Pneumocystis includes a group of closely related but heterogeneous organisms that have a worldwide distribution, have been detected in multiple mammalian species, are highly host species specific, inhabit the lungs almost exclusively, and have never convincingly been cultured in vitro, making Pneumocystis a fascinating but difficult-to-study organism. Improved molecular biologic methodologies have opened a new window into the biology and epidemiology of Pneumocystis. Advances include an improved taxonomic classification, identification of an extremely reduced genome and concomitant inability to metabolize and grow independent of the host lungs, insights into its transmission mode, recognition of its widespread colonization in both immunocompetent and immunodeficient hosts, and utilization of strain variation to study drug resistance, epidemiology, and outbreaks of infection among transplant patients. This review summarizes these advances and also identifies some major questions and challenges that need to be addressed to better understand Pneumocystis biology and its relevance to clinical care.
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Affiliation(s)
- Liang Ma
- Critical Care Medicine Department, NIH Clinical Center, Bethesda, Maryland, USA
| | - Ousmane H Cissé
- Critical Care Medicine Department, NIH Clinical Center, Bethesda, Maryland, USA
| | - Joseph A Kovacs
- Critical Care Medicine Department, NIH Clinical Center, Bethesda, Maryland, USA
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3
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Multilocus microsatellite genotyping array for investigation of genetic epidemiology of Pneumocystis jirovecii. J Clin Microbiol 2014; 52:1391-9. [PMID: 24523468 DOI: 10.1128/jcm.02531-13] [Citation(s) in RCA: 26] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/11/2022] Open
Abstract
Pneumocystis jirovecii is a symbiotic respiratory fungus that causes pneumonia (PcP) in immunosuppressed patients. Because P. jirovecii cannot be reliably cultured in vitro, it has proven difficult to study and gaps in our understanding of the organism persist. The release of a draft genome for the organism opens the door for the development of new genotyping approaches for studying its molecular epidemiology and global population structure. We identified and validated 8 putatively neutral microsatellite markers and 1 microsatellite marker linked to the dihydropteroate synthase gene (dhps), the enzymatic target of sulfa drugs used for PcP prevention and treatment. Using these tools, we analyzed P. jirovecii isolates from HIV-infected patients from three geographically distant populations: Uganda, the United States, and Spain. Among the 8 neutral markers, we observed high levels of allelic heterozygosity (average He, 0.586 to 0.842). Consistent with past reports, we observed limited global population structuring, with only the Ugandan isolates showing minor differentiation from the other two populations. In Ugandan isolates that harbored mutations in dhps, the microsatellite locus linked to dhps demonstrated a depressed He, consistent with positive directional selection for sulfa resistance mutations. Using a subset of these microsatellites, analyses of individual and paired samples from infections in San Francisco, CA, showed reliable typeability within a single infection and high discriminatory power between infections. These features suggest that this novel microsatellite typing approach will be an effective tool for molecular-epidemiological investigations into P. jirovecii population structure, transmission, and drug resistance.
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Jarboui MA, Mseddi F, Sellami H, Sellami A, Mahfoudh N, Makni F, Makni H, Ayadi A. A comparison of capillary electrophoresis and direct sequencing in upstream conserved sequence region analysis of Pneumocystis jirovecii strains. J Med Microbiol 2013; 62:560-564. [PMID: 23329318 DOI: 10.1099/jmm.0.045336-0] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
Abstract
The major surface glycoprotein (MSG) of Pneumocystis jirovecii is the most abundant surface protein and appears to play a critical role in the pathogenesis of pneumocystosis. The expressed MSG gene is located immediately downstream of a region called the upstream conserved sequence (UCS). The UCS contains a region of tandem repeats that vary in number and sequence. In the present study, we have used capillary electrophoresis and direct sequencing to detect the variability in the repeat units of UCS. By direct sequencing the PCR products from samples of 13 patients, we have identified three types of repeat units which consisted of 10 nt and three different patterns in the UCS region with three and four repeats: 1, 2, 3 (84.6 %); 1, 2, 3, 3 (8.2 %); and a new genotype 2, 2, 3, 3 (8.2 %). The same samples were analysed by capillary electrophoresis. Three samples (23 %) contained a mixture of two or three different patterns of UCS repeats. In conclusion, quantifying the number of repeat units in the UCS by capillary electrophoresis provides a potential new method for the rapid typing of P. jirovecii and the detection of mixed infection.
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Affiliation(s)
- M A Jarboui
- Fungal and Parasitic Molecular Biology Laboratory, School of Medicine, University of Sfax, Magida Boulila Street, 3029 Sfax, Tunisia
| | - F Mseddi
- Fungal and Parasitic Molecular Biology Laboratory, School of Medicine, University of Sfax, Magida Boulila Street, 3029 Sfax, Tunisia
| | - H Sellami
- Fungal and Parasitic Molecular Biology Laboratory, School of Medicine, University of Sfax, Magida Boulila Street, 3029 Sfax, Tunisia
| | - A Sellami
- Fungal and Parasitic Molecular Biology Laboratory, School of Medicine, University of Sfax, Magida Boulila Street, 3029 Sfax, Tunisia
| | - N Mahfoudh
- Laboratory of Immunology, Hedi Chaker hospital, Sfax, Tunisia
| | - F Makni
- Fungal and Parasitic Molecular Biology Laboratory, School of Medicine, University of Sfax, Magida Boulila Street, 3029 Sfax, Tunisia
| | - H Makni
- Laboratory of Immunology, Hedi Chaker hospital, Sfax, Tunisia
| | - A Ayadi
- Fungal and Parasitic Molecular Biology Laboratory, School of Medicine, University of Sfax, Magida Boulila Street, 3029 Sfax, Tunisia
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Ripamonti C, Orenstein A, Kutty G, Huang L, Schuhegger R, Sing A, Fantoni G, Atzori C, Vinton C, Huber C, Conville PS, Kovacs JA. Restriction fragment length polymorphism typing demonstrates substantial diversity among Pneumocystis jirovecii isolates. J Infect Dis 2009; 200:1616-22. [PMID: 19795979 DOI: 10.1086/644643] [Citation(s) in RCA: 26] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/03/2022] Open
Abstract
Better understanding of the epidemiology and transmission patterns of human Pneumocystis should lead to improved strategies for preventing Pneumocystis pneumonia (PCP). We have developed a typing method for Pneumocystis jirovecii that is based on restriction fragment length polymorphism (RFLP) analysis after polymerase chain reaction amplification of an approximately 1300 base-pair region of the msg gene family, which comprises an estimated 50-100 genes/genome. The RFLP pattern was reproducible in samples containing >1000 msg copies/reaction and was stable over time, based on analysis of serial samples from the same patient. In our initial analysis of 48 samples, we found that samples obtained from different individuals showed distinct banding patterns; only samples obtained from the same patient showed an identical RFLP pattern. Despite this substantial diversity, samples tended to cluster on the basis of country of origin. In an evaluation of samples obtained from an outbreak of PCP in kidney transplant recipients in Germany, RFLP analysis demonstrated identical patterns in samples that were from 12 patients previously linked to this outbreak, as well as from 2 additional patients. Our results highlight the presence of a remarkable diversity in human Pneumocystis strains. RFLP may be very useful for studying clusters of PCP in immunosuppressed patients, to determine whether there is a common source of infection.
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Affiliation(s)
- Chiara Ripamonti
- Critical Care Medicine Department, NIH Clinical Center, National Institutes of Health, Bethesda, MD 20892, USA
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Cushion MT, Walzer PD, Ashbaugh A, Rebholz S, Brubaker R, Vanden Eynde JJ, Mayence A, Huang TL. In vitro selection and in vivo efficacy of piperazine- and alkanediamide-linked bisbenzamidines against Pneumocystis pneumonia in mice. Antimicrob Agents Chemother 2006; 50:2337-43. [PMID: 16801410 PMCID: PMC1489771 DOI: 10.1128/aac.00126-06] [Citation(s) in RCA: 28] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
Bisbenzamidines, such as pentamidine isethionate, are aromatic dicationic compounds that are active against Pneumocystis and other microbes but are oftentimes toxic to the host. To identify potential anti-Pneumocystis agents, we synthesized bisbenzamidine derivatives in which the parent compound pentamidine was modified by a 1,4-piperazinediyl, alkanediamide, or 1,3-phenylenediamide moiety as the central linker. Several of the compounds were more active against P. carinii and less toxic than pentamidine in cytotoxicity assays. For this study, we evaluated nine bisbenzamidine derivatives representing a range of in vitro activities, from highly active to inactive, for the treatment of pneumocystosis in an immunosuppressed mouse model. Six of these in vitro-active compounds, 01, 02, 04, 06, 100, and 101, exhibited marked efficacies against infection at a dose of 10 mg/kg of body weight, and four compounds, 01, 04, 100, and 101, showed significant increases in survival versus that of untreated infected control mice. Compound 100 was highly efficacious against the infection at 20 mg/kg and 40 mg/kg, with > 1,000-fold reductions in burden, and resulted in improved survival curves versus those for pentamidine-treated mice (at the same doses). All six bisbenzamidine compounds that exhibited high in vitro activity significantly decreased the infection in vivo; two compounds, 12 and 102, with marked to moderate in vitro activities had slight or no activity in vivo, while compound 31 was inactive in vitro and was also inactive in vivo. Thus, the selection of highly active compounds from in vitro cytotoxicity assays was predictive of activity in the mouse model of Pneumocystis pneumonia. We conclude that a number of these bisbenzamidine compounds, especially compound 100, may show promise as new anti-Pneumocystis drugs.
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Affiliation(s)
- Melanie T Cushion
- Research Service, Veterans Affairs Medical Center, Cincinnati, OH 45220, USA.
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7
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Montes-Cano MA, de la Horra C, Martin-Juan J, Varela JM, Torronteras R, Respaldiza N, Medrano FJ, Calderón EJ. Pneumocystis jiroveci Genotypes in the Spanish Population. Clin Infect Dis 2004; 39:123-8. [PMID: 15206063 DOI: 10.1086/421778] [Citation(s) in RCA: 67] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/10/2003] [Accepted: 02/19/2004] [Indexed: 11/03/2022] Open
Abstract
This study describes the genotype distribution of Pneumocystis jiroveci in 79 respiratory samples obtained from 15 patients with acquired immunodeficiency syndrome (AIDS) with P. jiroveci pneumonia and 64 human immunodeficiency virus-negative subjects with different chronic pulmonary diseases. The genotyping was based in analysis of 2 independent genetic loci: the mitochondrial large subunit ribosomal RNA (mt LSU rRNA) fragment (assessed by direct sequencing) and the gene for dihydropteroate synthase (DHPS; assessed by restriction fragment-length polymorphism). The mt LSU rRNA analysis revealed the presence of 3 different polymorphisms for both populations. The major genotype, 85C/248C, was found to be significantly higher in patients with AIDS and P. jiroveci pneumonia than in patients with pulmonary disease. The rate of genotypes 85A/248C and 85T/248C was similar in both groups. The analysis of DHPS genotypes assesses the prevalence of its 4 possible genotypes, with 35.5% of genotypes related to sulfa resistance. The data suggest a common source of infection between both groups.
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Affiliation(s)
- M A Montes-Cano
- Department of Internal Medicine, Virgen del Rocio University Hospital, Seville, Spain
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8
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Guillot J, Demanche C, Norris K, Wildschutte H, Wanert F, Berthelemy M, Tataine S, Dei-Cas E, Chermette R. Phylogenetic relationships among Pneumocystis from Asian macaques inferred from mitochondrial rRNA sequences. Mol Phylogenet Evol 2004; 31:988-96. [PMID: 15120396 DOI: 10.1016/j.ympev.2003.10.022] [Citation(s) in RCA: 17] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/06/2003] [Revised: 09/05/2003] [Indexed: 11/24/2022]
Abstract
The presence of Pneumocystis organisms was detected by nested-PCR at mitochondrial large subunit (mtLSU) rRNA gene in 23 respiratory samples from Asian macaques representing two species: Macaca mulatta and M. fascicularis. A very high level of sequence heterogeneity was detected with 18 original sequence types. Two genetic groups of Pneumocystis could be distinguished from the samples. Within each group, the extent of genetic divergence was low (2.5+/-1.4% in group 1 and 2.3+/-1.7% in group 2). Genetic divergences were systematically higher when macaque-derived sequence types were compared with Pneumocystis mtLSU sequences from other primate species (from 5.3+/-2.7% to 19.3+/-3.0%). The two macaque-derived groups may be considered as distinct Pneumocystis species. Surprisingly, these Pneumocystis species were recovered from both M. mulatta and M. fascicularis suggesting that host-species restriction may not systematically occur in the genus Pneumocystis. Alternatively, these observations question about the species concept in macaques.
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Affiliation(s)
- Jacques Guillot
- Equipe de Mycologie, UMR INRA-AFSSA-ENVA-UPVM, Biologie Moléculaire et Immunologie Parasitaires et Fongiques, Ecole Nationale Vétérinaire d'Alfort, Alfort, France.
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9
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Manoloff ES, Francioli P, Taffé P, van Melle G, Bille J, Hauser PM. Risk for Pneumocystis carinii transmission among patients with pneumonia: a molecular epidemiology study. Emerg Infect Dis 2003; 9:132-4. [PMID: 12533297 PMCID: PMC2873751 DOI: 10.3201/eid0901.020141] [Citation(s) in RCA: 35] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/19/2022] Open
Abstract
We report a molecular typing and epidemiologic analysis of Pneumocystis carinii pneumonia (PCP) cases diagnosed in our geographic area from 1990 to 2000. Our analysis suggests that transmission from patients with active PCP to susceptible persons caused only a few, if any, PCP cases in our setting.
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Affiliation(s)
| | | | | | | | - Jacques Bille
- Centre Hospitalier Universitaire Vaudois, Lausanne, Switzerland
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10
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Abstract
Pneumocystis organisms can cause pneumonia in mammals that lack a strong immune defense. The genus Pneumocystis contains many different organisms that can be distinguished by DNA sequence analysis. These different organisms are different species of yeast-like fungi that are most closely related to the ascomycete, Schizosaccharomyces pombe. Each species of Pneumocystis appears to be specific for the mammal in which it is found. The species that infects humans is Pneumocystis jiroveci. P. jiroveci has not been found in any other mammal and the species of Pneumocystis found in other mammals have not been seen in humans. Genetic variation among P. jiroveci samples is common, suggesting that there are many strains. Strain analysis shows that adults can be infected by more than one strain, and suggests that pneumonia can be the result of infection occurring proximal to the time of disease, rather than to reactivation of dormant organisms acquired in early childhood. Nevertheless, long-term colonisation may be occurring. A large fraction of normal children and animals show evidence of infection. A Pneumocystis species that grows in rats has been shown to possess a complex genetic system for surface antigen variation, a strategy employed by other microbes that dwell in immunocompetent hosts. These findings, together with strong host specificity, suggest that Pneumocystis species may be obligate parasites. The source of infection is not clear. Pneumocystis DNA is detectable in the air, but is scarce except in environments occupied by individuals with Pneumocystis pneumonia. In a few cases, there is direct evidence of person to person transmission. In general, however, patients and their contacts have been found to have different strains of P. jiroveci.
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Affiliation(s)
- James R Stringer
- Department of Molecular Genetics, Biochemistry and Microbiology, University of Cincinnati, Cincinnati, OH 45220-0524, USA.
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Stringer JR, Beard CB, Miller RF, Wakefield AE. A new name (Pneumocystis jiroveci) for Pneumocystis from humans. Emerg Infect Dis 2002; 8:891-6. [PMID: 12194762 PMCID: PMC2732539 DOI: 10.3201/eid0809.020096] [Citation(s) in RCA: 271] [Impact Index Per Article: 12.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/19/2022] Open
Abstract
The disease known as Pneumocystis carinii pneumonia (PCP) is a major cause of illness and death in persons with impaired immune systems. While the genus Pneumocystis has been known to science for nearly a century, understanding of its members remained rudimentary until DNA analysis showed its extensive diversity. Pneumocystis organisms from different host species have very different DNA sequences, indicating multiple species. In recognition of its genetic and functional distinctness, the organism that causes human PCP is now named Pneumocystis jiroveci Frenkel 1999. Changing the organism's name does not preclude the use of the acronym PCP because it can be read "Pneumocystis pneumonia." DNA sequence variation exists among samples of P. jiroveci, a feature that allows reexamination of the relationships between host and pathogen. Instead of lifelong latency, transient colonization may be the rule.
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Affiliation(s)
- James R Stringer
- Department of Molecular Genetics, Biochemistry and Microbiology, University of Cincinnati, Cincinnati, Ohio 45267-0524, USA.
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Cornillot E, Keller B, Cushion MT, Méténier G, Vivarès CP. Fine analysis of the Pneumocystis carinii f. sp. carinii genome by two-dimensional pulsed-field gel electrophoresis. Gene 2002; 293:87-95. [PMID: 12137946 DOI: 10.1016/s0378-1119(02)00604-2] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/27/2022]
Abstract
Pneumocystis carinii is a general designation for a group of unusual unicellular fungal parasites responsible of pneumopathy in animal hosts. Divided into several subgroups termed the 'special forms', P. carinii is prone to an extensive karyotype variation. In previous studies, the nuclear genome of these organisms has been considered to be haploid and a set of 16 chromosomes has been assigned to P. carinii f. sp. carinii, a special form known to infect rats. We report the analysis of the genome of an isolate representative of the karyotype 1 of this special form, using two-dimensional pulsed-field gel electrophoresis procedures. The 'karyotype and restriction display' (KARD) fingerprints indicated the presence of 17 different chromosomes. The haploid genome size was estimated to be 8.4 Mbp. Some homologous chromosomes were distinguished on the basis of a single restriction fragment length polymorphism, which raises the possibility of a diploid nucleus. A restriction map of the chromosome 15, characterized by two homologues with a size difference of 7 kb, was constructed. Hybridization data indicated that insertion/deletion events may have occurred within subtelomeric regions which carry genes encoding the major surface glycoprotein (MSG) of Pneumocystis.
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Affiliation(s)
- Emmanuel Cornillot
- Parasitologie Moléculaire et Cellulaire, LBP, UMR CNRS 6023, Université Blaise Pascal, Bâtiment Biologie A, Campus universitaire des Cézeaux, Aubière, France.
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13
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Nimri LF, Moura INS, Huang L, del Rio C, Rimland D, Duchin JS, Dotson EM, Beard CB. Genetic diversity of Pneumocystis carinii f. sp. hominis based on variations in nucleotide sequences of internal transcribed spacers of rRNA genes. J Clin Microbiol 2002; 40:1146-51. [PMID: 11923323 PMCID: PMC140386 DOI: 10.1128/jcm.40.4.1146-1151.2002] [Citation(s) in RCA: 32] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/15/2001] [Revised: 12/10/2001] [Accepted: 01/07/2002] [Indexed: 01/19/2023] Open
Abstract
A variety of genes have been used to type Pneumocystis carinii. In the present study, nucleotide sequence variations in the ITS1 and ITS2 internal transcribed spacer (ITS) regions of the rRNA genes were used to type Pneumocystis carinii f. sp. hominis DNA obtained from the lungs of 60 human immunodeficiency virus-infected individuals. These regions were amplified by PCR, cloned, and sequenced. Multibase polymorphisms were identified among samples. Several new genotypes are reported on the basis of the nucleotide sequence variations at previously unreported positions of both the ITS1 and the ITS2 regions. Twelve new ITS1 sequences were observed, in addition to the nine sequence types reported previously. The most common was type E, which was observed in 60.5% of the samples. The sequence variations in the ITS1 region were mainly located at positions 5, 12, 23, 24, 45, 53, and 54. Sixteen new ITS2 types were also identified, in addition to the 13 types reported previously. The most common was type g (26.6%). The sequences of the ITS2 regions in most specimens were different from the previously published sequence at bases 120 and 166 through 183. The most common variations observed were deletions at positions 177 through 183. The presence of more than one sequence type in some patients (60%) suggested the occurrence of coinfection with multiple P. carinii strains. The genetic polymorphism observed demonstrates the degree of diversity of Pneumocystis strains that infect humans. Furthermore, the high degree of polymorphism suggests that these genes are evolving faster than other genes. Consequently, the sequence information derived is useful for purposes such as examination of the potential of person-to-person transmission and recurrent infections but perhaps not for other genotyping applications that rely on more stable genetic loci.
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Affiliation(s)
- Laila F Nimri
- Centers for Disease Control and Prevention, Atlanta, Georgia, USA.
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Helweg-Larsen J, Lundgren B, Lundgren JD. Heterogeneity and compartmentalization of Pneumocystis carinii f. sp. hominis genotypes in autopsy lungs. J Clin Microbiol 2001; 39:3789-92. [PMID: 11574620 PMCID: PMC88436 DOI: 10.1128/jcm.39.10.3789-3792.2001] [Citation(s) in RCA: 20] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/23/2022] Open
Abstract
The extent and importance of genotype heterogeneity of Pneumocystis carinii f. sp. hominis within lungs have not previously been investigated. Two hundred forty PCR clones obtained from respiratory specimens and lung segments from three patients with fatal P. carinii pneumonia were investigated to detect genetic diversity in the internal transcribed spacer (ITS) region of the nuclear rRNA operon, the mitochondrial large-subunit (mtLSU) rRNA gene, and the dihydropteroate synthase-encoding gene. For two of the three examined patients, a mixture of different mtLSU rRNA and ITS genotypes was observed. Not all genotypes present in the lungs at autopsy were detected in the diagnostic respiratory samples. Compartmentalization of specific ITS and mtLSU rRNA sequence types was observed in different lung segments. In conclusion, the interpretation of genotype data and in particular ITS sequence types in the assessment of epidemiological questions should be cautious since genotyping done on respiratory samples cannot a priori be assumed to represent all genotypes present within the lung.
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Affiliation(s)
- J Helweg-Larsen
- Department of Infectious Diseases, Hvidovre University Hospital, Copenhagen, Denmark.
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15
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Hauser PM, Blanc DS, Sudre P, Senggen Manoloff E, Nahimana A, Bille J, Weber R, Francioli P. Genetic diversity of Pneumocystis carinii in HIV-positive and -negative patients as revealed by PCR-SSCP typing. AIDS 2001; 15:461-6. [PMID: 11242142 DOI: 10.1097/00002030-200103090-00004] [Citation(s) in RCA: 54] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/26/2022]
Abstract
OBJECTIVE To describe the epidemiology of severe Pneumocystis carinii pneumonia (PCP) in HIV-infected and non HIV-infected patients. METHODS Bronchoalveolar lavage specimens from 212 European patients with PCP were typed using PCR--single strand conformation polymorphism analysis of four genomic regions of P. carinii f. sp. hominis. Demographic and clinical information was obtained from all patients. RESULTS Twenty-three per cent of the patients were presumably infected with a single P. c. hominis type. The other patients presented with two (50%) or more (27%) types. Thirty-five genetically stable and ubiquitous P. c. hominis types were found. Their frequency ranged from 0.4% to 10% of all isolates, and up to 15% of those from a given hospital. There was no significant association between the P. c. hominis type or number of co-infecting types per patient and geographical location, year of collection, sex, age, or HIV status. No more than three patients infected with the same type were observed in the same hospital within the same 6 month period, and no epidemiological link between the cases was found. CONCLUSIONS The broad diversity of types observed seems to indicate that multiple sources of the pathogen co-exist. There was no evidence that in our study population inter-human transmission played a significant role in the epidemiology of P. carinii.
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Affiliation(s)
- P M Hauser
- Division autonome de Médecine Préventive Hospitalière, Centre Hospitalier Universitaire Vaudois, Lausanne, Switzerland
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Ma L, Kovacs JA. Rapid detection of mutations in the human-derived Pneumocystis carinii dihydropteroate synthase gene associated with sulfa resistance. Antimicrob Agents Chemother 2001; 45:776-80. [PMID: 11181359 PMCID: PMC90372 DOI: 10.1128/aac.45.3.776-780.2001] [Citation(s) in RCA: 16] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
Recent studies have shown that point mutations in the dihydropteroate synthase (DHPS) gene of human-derived Pneumocystis carinii are related to exposure to sulfa drugs and possibly represent the emergence of sulfa resistance. We developed a simple single-strand conformation polymorphism (SSCP) method to permit rapid detection of these mutations. With plasmid constructs, SSCP was able to detect as little as 10% of a minority population. The SSCP assay was compared to direct sequencing for typing the DHPS gene by examining 37 clinical isolates with known DHPS sequences and 41 clinical isolates with unknown DHPS sequences. The typing results were consistent between these two methods for all isolates except 11 in which mutations were detected by SSCP but not by direct sequencing. Sequencing of individual clones after subcloning confirmed the presence of mutations in a minority population as determined by SSCP. SSCP is a very simple and sensitive method for rapid identification of P. camii DHPS mutations.
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Affiliation(s)
- L Ma
- Critical Care Medicine Department, Warren Grant Magnuson Clinical Center, National Institutes of Health, Bethesda, Maryland 20892, USA
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17
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Amit Z, Kaneshiro ES. Heterogeneity of Pneumocystis sterol profiles of samples from different sites in the same pair of lungs suggests coinfection by distinct organism populations. J Clin Microbiol 2001; 39:1137-9. [PMID: 11230442 PMCID: PMC87888 DOI: 10.1128/jcm.39.3.1137-1139.2001] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
Sterol profiles of samples taken from different sites of a Pneumocystis-infected human lung showed large variations in pneumocysterol similar to those that occur among samples from different patients. Thus, the influence of diet or drugs on pneumocysterol accumulation was ruled out, suggesting distinct phenotypic populations as the basis for the heterogeneity.
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Affiliation(s)
- Z Amit
- Department of Biological Sciences, University of Cincinnati, Cincinnati, Ohio 45221, USA
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18
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Cushion MT, Orr S, Keely SP, Stringer JR. Time between inoculations and karyotype forms of Pneumocystis carinii f. sp. Carinii influence outcome of experimental coinfections in rats. Infect Immun 2001; 69:97-107. [PMID: 11119494 PMCID: PMC97860 DOI: 10.1128/iai.69.1.97-107.2001] [Citation(s) in RCA: 13] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/11/2000] [Accepted: 09/27/2000] [Indexed: 11/20/2022] Open
Abstract
The prevalence of Pneumocystis carinii pneumonia (PCP) in humans caused by more than a single genotype has been reported to range from 10 to 67%, depending on the method used for detection (3, 19). Most coinfections were associated with primary rather than recurrent disease. To better understand the factors influencing the development of coinfections, the time periods between inoculations and the genotype of the infecting organisms were evaluated in the chronically immunosuppressed-inoculated rat model of PCP. P. carinii f. sp. carinii infecting rats differentiated by karyotypic profiles exhibit the same low level of genetic divergence manifested by organisms infecting humans. P. carinii f. sp. carinii karyotype forms 1, 2, and 6 were inoculated into immunosuppressed rats, individually and in dual combinations, spaced 0, 10, and 20 days apart. Infections comprised of both organism forms resulted from admixtures inoculated at the same time. In contrast, coinfections did not develop in most rats, where a 10- or 20-day gap was inserted between inoculations; only the first organism form inoculated was detected by pulsed-field gel electrophoresis in the resultant infection. Organism burdens were reduced with combinations of forms 1 and 2 spaced 20 days apart but not in rats inoculated with forms 1 and 6. A role for the host response in the elimination of the second population and in reduction of the organism burden was suggested by the lack of direct killing of forms 1 and 2 in an in vitro ATP assay, by reduction of the burden by autoclaved organisms, and by the specific reactions of forms 1 and 2 but not forms 1 and 6. These studies showed that the time between inoculations was critical in establishing coinfections and P. carinii f. sp. carinii karyotype profiles were associated with differences in biological responses. This model provides a useful method for the study of P. carinii coinfections and their transmission in humans.
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Affiliation(s)
- M T Cushion
- Department of Internal Medicine, Division of Infectious Diseases, University of Cincinnati College of Medicine, Cincinnati, Ohio 45267-0560, USA.
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19
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Hauser PM, Blanc DS, Bille J, Nahimana A, Francioli P. Carriage of Pneumocystis carinii by immunosuppressed patients and molecular typing of the organisms. AIDS 2000; 14:461-3. [PMID: 10770551 DOI: 10.1097/00002030-200003100-00022] [Citation(s) in RCA: 25] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/26/2022]
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20
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Beard CB, Carter JL, Keely SP, Huang L, Pieniazek NJ, Moura IN, Roberts JM, Hightower AW, Bens MS, Freeman AR, Lee S, Stringer JR, Duchin JS, del Rio C, Rimland D, Baughman RP, Levy DA, Dietz VJ, Simon P, Navin TR. Genetic variation in Pneumocystis carinii isolates from different geographic regions: implications for transmission. Emerg Infect Dis 2000; 6:265-72. [PMID: 10827116 PMCID: PMC2640877 DOI: 10.3201/eid0603.000306] [Citation(s) in RCA: 189] [Impact Index Per Article: 7.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/11/2023] Open
Abstract
To study transmission patterns of Pneumocystis carinii pneumonia (PCP) in persons with AIDS, we evaluated P. carinii isolates from patients in five U.S. cities for variation at two independent genetic loci, the mitochondrial large subunit rRNA and dihydropteroate synthase. Fourteen unique multilocus genotypes were observed in 191 isolates that were examined at both loci. Mixed infections, accounting for 17.8% of cases, were associated with primary PCP. Genotype frequency distribution patterns varied by patients' place of diagnosis but not by place of birth. Genetic variation at the two loci suggests three probable characteristics of transmission: that most cases of PCP do not result from infections acquired early in life, that infections are actively acquired from a relatively common source (humans or the environment), and that humans, while not necessarily involved in direct infection of other humans, are nevertheless important in the transmission cycle of P. carinii f. sp. hominis.
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Affiliation(s)
- C B Beard
- Centers for Disease Control and Prevention, Atlanta, Georgia 30341-3724, USA.
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21
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Épidémiologie moléculaire de la pneumocystose humaine. Med Mal Infect 1999. [DOI: 10.1016/s0399-077x(00)88282-7] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/19/2022]
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22
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Hauser PM, Blanc DS, Telenti A, Nahimana A, Bille J, Francioli P. Potential coinfections complicate typing of Pneumocystis carinii f. sp. hominis. J Clin Microbiol 1998; 36:3111. [PMID: 9841244 PMCID: PMC105129 DOI: 10.1128/jcm.36.10.3111-3111.1998] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
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