Isoform Diversity and Tandem Duplication of the Glycoprotein A Gene in Ferret Pneumocystis carinii

Wright, Terry W.; Bissoondial, Terrence Y.; Haidaris, Constantine G.; Gigliotti, Francis; Haidaris, Patricia J.

doi:10.1093/dnares/2.2.77

Cited by 39 publications

(28 citation statements)

References 47 publications

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“…The biological role of these tandem repeats in the UCS region is unknown but the UCS is considered to be essential for the expression of MSG. A similar MSG gene organization has also been identified in rat, mouse and ferret Pneumocystis (Kutty et al, 2001;Haidaris et al, 1998;Wright et al, 1995). Since Pneumocystis is haploid and the UCS is present as a single copy per genome, quantifying the number of repeats provides a potential easy method for rapidly typing P. jirovecii.…”

Section: Discussionmentioning

confidence: 74%

A comparison of capillary electrophoresis and direct sequencing in upstream conserved sequence region analysis of Pneumocystis jirovecii strains

Jarboui

Mseddi

Sellami

et al. 2013

Journal of Medical Microbiology

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The MSG is encoded by a multi-copy gene family, with an estimated 80 copies per genome, which are clustered in tandem arrays near the telomeres of each chromosome. Pneumocystis can vary its expressed MSG, presumably as a mechanism to avoid the host immune system (Keely & Stringer, 2009;Cornillot et al., 2002;Keely et al., 2005).The MSG gene is located immediately downstream of a region called the upstream conserved sequence (UCS). The UCS is considered to be essential for the expression of MSG and contains a region of 10 nt tandem repeats with variation in the sequence and in the number of repeats (Kutty et al., 2001;Ma et al., 2002; Esteves et al., 2009).The aim of the present study was to analyse the tandem repeats in the UCS intron of MSG by direct sequencing and to develop a simple and rapid capillary electrophoresis method for typing P. jirovecii and for the detection of mixed infection. METHODSThe study was performed on samples from 13 immunocompromised patients, including 10 HIV-positive patients, two kidney transplant patients and one leukaemia patient. These patients were identified as positive after the amplification of the P. jirovecii mtLSUrRNA gene by PCR (Jarboui et al., 2010).Clinical specimens [bronchoalveolar lavage (BAL) and sputum] isolated from these patients were centrifuged at 1500 g for 5 min and the pellet was digested overnight by proteinase K at 56 uC. DNA was extracted using a commercial kit from Qiagen (QIAamp DNA Minikit; Qiagen).PCR amplification. The PCR assay for the mtLSUrRNA gene was carried out in 50 ml, containing 2.5 mM MgCl 2 ; 0.25 mM each of dATP, dTTP, dCTP and dGTP; 0.25 mM of each primer; and 2.5 U of Taq DNA polymerase (Promega).For the amplification of the UCS genomic DNA sequence of the P. jirovecii MSG gene, we used four primers ( Fig. 1

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Section: Discussionmentioning

confidence: 74%

A comparison of capillary electrophoresis and direct sequencing in upstream conserved sequence region analysis of Pneumocystis jirovecii strains

Jarboui

Mseddi

Sellami

et al. 2013

Journal of Medical Microbiology

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“…MSG genes are organized as clusters of 2 to 4 genes (39,144,148,166,167,179). If each of the 30 to 36 chromosome ends in the genome has 2 to 4 MSG genes, then the number of genes per genome is between 60 and 144.…”

Section: Msg Genes: Number and Organizationmentioning

confidence: 99%

“…Such crossovers could involve a site-specific recombinase because all MSG genes possess a common 23-bp sequence called the conserved recombination junction element (CRJE) (170), which could serve as the target of such a recombinase. However, recent findings have shown that the CRJE differs among special forms, so if a recombinase is at work, it would appear to have different targets in different special forms (49,127,179).…”

Section: Model For Control Of Msg Gene Transcriptionmentioning

confidence: 99%

Genetics of Surface Antigen Expression inPneumocystis carinii

Stringer

Keely

2001

Infect Immun

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This article reviews the molecular genetic data pertaining to the major surface glycoprotein (MSG) gene family of Pneumocystis carinii and its role in surface variation and compares this fungal system to antigenic variation systems in the protozoan Trypanosoma brucei and the bacteria Borrelia spp. PNEUMOCYSTIS CARINIIPneumocystis carinii is a fungus that can cause pneumonia in immunocompromised mammals (100, 174). While P. carinii was recognized nearly a century ago and has been a significant human pathogen since the beginning of the AIDS epidemic, this organism is not well understood. Much of the blame for the lack of basic information about this organism and its natural history can be placed on its failure to grow well in culture. Populations of the organism can be maintained in broth culture, but growth in culture has not been good enough to allow either production of large numbers or derivation of clonally derived stocks (95). Therefore, in vitro culture has been of limited utility for studying the genetics and biochemistry of P. carinii.By contrast, large numbers of organisms can be routinely obtained from laboratory animals. Most of what is known about P. carinii has been learned from studies with animals, and most of what is known about the surface antigen genes was determined from studies on organisms from laboratory rats. Reliance on rats as the source of P. carinii has had its advantages and disadvantages, which have shaped the course of research on antigenic variation. It is important, therefore, to preface this review with a brief description of the general features of rat models of P. carinii infection.The rat model of P. carinii pneumonia (Pcp) has its roots in studies that showed that P. carinii infections can be provoked by treating rats with chemical immunosuppressants (18,24,38,53). These infections appeared to be caused by growth of P. carinii that was present in the rats at the time of immunosuppression (reactivation of latent infections). Most, if not all, commercial rat colonies harbor P. carinii in a latent form, where it can persist for up to a year (103,162,178). It seems most plausible that P. carinii maintains itself in rat colonies via airborne transmission from older rats to neonates, and evidence for airborne transmission has been obtained in laboratory settings (53,55,176). However, other mechanisms of transmission from adults to neonates have not been excluded, and observations suggestive of transplacental transfer have been reported (17).Even though latent infections are common in laboratory rats, simply immunosuppressing rats does not always lead to the production of large numbers of organisms per animal. This observation led to the implementation of a protocol known as the natural transmission method. In this method, rats are bred in colonies known to harbor latent infections. Young animals in such colonies are immunosuppressed and housed in openair cages. Some or all of the immunosuppressed animals develop heavy infections. When new young animals from another source (such as a...

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“…In fact, the duplication must have occurred after the divergence of the otherwise very closely related species, P. carinii and P. muris, since the latter also has been reported elsewhere to have only a single copy of this gene (11). This is very different from the MSG gene family, since the genomes of all Pneumocystis species examined to date contain multiple copies of MSG genes, whose duplication must have occurred in a very early ancestor of most or all of the present-day Pneumocystis species (5,8,24).…”

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confidence: 94%