Functional and Expression Analyses of the
            <i>Pneumocystis MAT</i>
            Genes Suggest Obligate Sexuality through Primary Homothallism within Host Lungs

Richard, Sophie; Almeida, João M. G. C. F.; Cissé, Ousmane; Luraschi, Amanda; Nielsen, Olaf; Pagni, Marco; Hauser, Philippe M.

doi:10.1128/mbio.02201-17

Cited by 21 publications

(18 citation statements)

References 44 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…The PCP PCR targets the mitochondrial 26S rDNA. The primers and protocol used in this study have been described elsewhere [ 11 ]. In brief, the BAL was centrifuged 30 min at 3000 g and the pellet was resuspended in remaining 2 ml of liquid.…”

Section: Methodsmentioning

confidence: 99%

Ability of quantitative PCR to discriminate Pneumocystis jirovecii pneumonia from colonization

Perret

Kritikos

Hauser

et al. 2020

Journal of Medical Microbiology

View full text Add to dashboard Cite

Introduction. Pneumocystis jirovecii pneumonia (PCP) is a severe disease affecting immunocompromised patients. Diagnosis is difficult due to the low sensitivity of direct examination and inability to grow the pathogen in culture. Quantitative PCR in bronchoalveolar lavage fluid (BAL) has high sensitivity, but limited specificity for distinguishing PCP from colonization. Aim. To assess the performance of an in-house quantitative PCR to discriminate between PCP and colonization. Methodology. This was a single-centre retrospective study including all patients with a positive PCR result for P. jirovecii in BAL between 2009 and 2017. Irrespective of PCR results, PCP was defined as the presence of host factors and clinical/radiological criteria consistent with PCP and (i) the presence of asci at direct examination of respiratory sample or (ii) anti-PCP treatment initiated with clinical response and absence of alternative diagnosis. Colonization was considered for cases who did not receive anti-PCP therapy with a favourable outcome or an alternative diagnosis. Cases who did not meet the above mentioned criteria were classified as ‘undetermined’. Results. Seventy-one patients with positive P. jirovecii PCR were included (90 % non-HIV patients). Cases were classified as follows: 37 PCP, 22 colonization and 12 undetermined. Quantitative PCR values in BAL were significantly higher in patients with PCP versus colonization or undetermined ( P <0.0001). The cut-off of 5×10 3 copies/ml was able to discriminate PCP cases from colonization with 97 % sensitivity, 82 % specificity, 90 % positive predictive value and 95 % negative predictive value. Conclusions. Our quantitative PCR for P. jirovecii in BAL was reliable to distinguish PCP cases from colonization in this predominantly non-HIV population.

show abstract

Section: Methodsmentioning

confidence: 99%

Ability of quantitative PCR to discriminate Pneumocystis jirovecii pneumonia from colonization

Perret

Kritikos

Hauser

et al. 2020

Journal of Medical Microbiology

View full text Add to dashboard Cite

show abstract

“…To investigate this issue in humans, we used reverse transcriptase PCR analysis of total RNAs extracted from 10 bronchoalveolar lavage (BAL) fluid samples from 10 patients with PCP. We previously analyzed these samples for the expression of the MAT genes and ensured that the RNAs did not contain genomic DNA by (i) the lack of amplification in the absence of reverse transcription and (ii) the lack of intron in the PCR product from the unrelated gene encoding β-tubulin (β -tub ) (17). For a control in the experiments of the present study, we repeated the latter amplification and consistently obtained the same results (Fig.…”

Section: Resultsmentioning

confidence: 99%

“…a+, positive PCR result; − , negative PCR result. The amplification results of the P. jirovecii MAT genes are from Richard et al (17) (the BAL fluid sample from patient 10 could not be analyzed here because it was no longer available).bAmplification of β- tub was used as control.…”

Section: Resultsmentioning

confidence: 99%

“…This suggested that these species are primary homothallic fungi. This hypothesis was further supported by ascertaining the function of one Pneumocystis MAT gene through restoration of sporulation in Schizosaccharomyces pombe, and the concomitant expression of the MAT genes during infection (17). The latter observation suggested that Pneumocystis sexuality is obligate within the host’s lungs in order to complete the cell cycle and produce asci that are necessary for the dissemination of the fungus.…”

Section: Introductionmentioning

confidence: 97%

See 1 more Smart Citation

Expression and Immunostaining Analyses Suggest that Pneumocystis Primary Homothallism Involves Trophic Cells Displaying Both Plus and Minus Pheromone Receptors

Luraschi

Richard

Almeida

et al. 2019

mBio

Self Cite

View full text Add to dashboard Cite

The genus Pneumocystis encompasses fungal species that colonize mammals’ lungs with host specificity. Should the host immune system weaken, the fungal species can cause severe pneumonia. The life cycle of these pathogens is poorly known, mainly because an in vitro culture method has not been established. Both asexual and sexual cycles would occur. Trophic cells, the predominant forms during infection, could multiply asexually but also enter into a sexual cycle. Comparative genomics revealed a single mating type locus, including plus and minus genes, suggesting that primary homothallism involving self-fertility of each strain is the mode of reproduction of Pneumocystis species. We identified and analyzed the expression of the mam2 and map3 genes encoding the receptors for plus and minus pheromones using reverse transcriptase PCR, in both infected mice and bronchoalveolar lavage fluid samples from patients with Pneumocystis pneumonia. Both receptors were most often concomitantly expressed during infection, revealing that both pheromone-receptor systems are involved in the sexual cycle. The map3 transcripts were subject to alternative splicing. Using immunostaining, we investigated the presence of the pheromone receptors at the surfaces of Pneumocystis cells from a patient. The staining tools were first assessed in Saccharomyces cerevisiae displaying the Pneumocystis receptors at their cellular surface. Both receptors were present at the surfaces of the vast majority of the cells that were likely trophic forms. The receptors might have a role in mate recognition and/or postfertilization events. Their presence at the cell surface might facilitate outbreeding versus inbreeding of self-fertile strains. IMPORTANCE The fungi belonging to the genus Pneumocystis may cause severe pneumonia in immunocompromised humans, a disease that can be fatal if not treated. This disease is nowadays one of the most frequent invasive fungal infections worldwide. Whole-genome sequencing revealed that the sexuality of these fungi involves a single partner that can self-fertilize. Here, we report that two receptors recognizing specifically excreted pheromones are involved in this self-fertility within infected human lungs. Using fluorescent antibodies binding specifically to these receptors, we observed that most often, the fungal cells display both receptors at their surface. These pheromone-receptor systems might play a role in mate recognition and/or postfertilization events. They constitute an integral part of the Pneumocystis obligate sexuality within human lungs, a cycle that is necessary for the dissemination of the fungus to new individuals.

show abstract

“…to complete its life cycle. Both studies were recently published (Cushion et al 2018;Richard et al 2018).…”

Section: Life Cyclementioning

confidence: 99%

The 14th International Workshops on Opportunistic Protists (IWOP 14)

Cushion

Limper

Porollo

et al. 2018

J Eukaryotic Microbiology

View full text Add to dashboard Cite

The 14th International Workshops on Opportunistic Protists (IWOP-14) was held August 10-12, 2017 in Cincinnati, OH, USA. The IWOP meetings focus on opportunistic protists (OIs); for example, free-living amoebae, Pneumocystis spp., Cryptosporidium spp., Toxoplasma, the Microsporidia, and kinetoplastid flagellates. The highlights of Pneumocystis spp. research included the reports of primary homothallism for mating; a potential requirement for sexual replication in its life cycle; a new antigen on the surface of small asci; roles for CLRs, Dectin-1, and Mincle in host responses; and identification of MSG families and mechanisms used for surface variation. Studies of Cryptosporidia spp. included comparative genomics, a new cryopreservation method; the role of mucin in attachment and invasion, and epidemiological surveys illustrating species diversity in animals. One of the five identified proteins in the polar tube of Microsporidia, PTP4, was shown to play a role in host infection. Zebrafish were used as a low cost vertebrate animal model for an evaluation of potential anti-toxoplasma drugs. Folk medicine compounds with anti-toxoplasma activity were presented, and reports on the chronic toxoplasma infection provided evidence for increased tractability for the study of this difficult life cycle stage. Escape from the parasitophorus vacuole and cell cycle regulation were the topics of the study in the acute phase.

show abstract

Functional and Expression Analyses of the Pneumocystis MAT Genes Suggest Obligate Sexuality through Primary Homothallism within Host Lungs

Cited by 21 publications

References 44 publications

Ability of quantitative PCR to discriminate Pneumocystis jirovecii pneumonia from colonization

Ability of quantitative PCR to discriminate Pneumocystis jirovecii pneumonia from colonization

Expression and Immunostaining Analyses Suggest that Pneumocystis Primary Homothallism Involves Trophic Cells Displaying Both Plus and Minus Pheromone Receptors

The 14th International Workshops on Opportunistic Protists (IWOP 14)

Contact Info

Product

Resources

About