Functional analysis of atfA gene to stress response in pathogenic thermal dimorphic fungus Penicillium marneffei

Penicillium marneffei, the pathogenic thermal dimorphic fungus is a causative agent of a fatal systemic disease, penicilliosis marneffei, in immunocompromised patients especially HIV patients. For growth and survival, this fungus has to adapt to environmental stresses outside and inside host cells and this adaptation requires stress signaling pathways and regulation of gene expression under various kinds of stresses. In this report, P. marneffei activating transcription factor (atfA) gene encoding bZip-type transcription factor was characterized. To determine functions of this gene, atfA isogenic mutant strain was constructed using the modified split marker recombination method. The phenotypes and susceptibility to varieties of stresses including osmotic, oxidative, heat, UV, cell wall and cell membrane stresses of the mutant strain were compared with the wild type and the atfA complemented strains. Results demonstrated that the mRNA expression level of P. marneffei atfA gene increased under heat stress at 42 degrees C. The atfA mutant was more sensitive to sodium dodecyl sulphate, amphotericin B and tert-butyl hydroperoxide than the wild type and complemented strains but not hydrogen peroxide, menadione, NaCl, sorbitol, calcofluor white, itraconazole, UV stresses and heat stress at 39 degrees C. In addition, recovery of atfA mutant conidia after mouse and human macrophage infections was significantly decreased compared to those of wild type and complemented strains. These results indicated that the atfA gene was required by P. marneffei under specific stress conditions and might be necessary for fighting against host immune cells during the initiation of infection.published_or_final_versio

Immune reconstitution inflammatory syndrome from Penicillium marneffei in an HIV-infected child: a case report and review of literature

<p>Abstract</p> <p>Backgrounds</p> <p>Disseminated <it>Penicillium marneffei </it>infection is one of the most common HIV-related opportunistic infections in Southeast Asia. Immune reconstitution inflammatory syndrome (IRIS) is a complication related to antiretroviral therapy (ART)-induced immune restoration. The aim of this report is to present a case of HIV-infected child who developed an unmasking type of IRIS caused by disseminated <it>P. marneffei </it>infection after ART initiation.</p> <p>Case presentation</p> <p>A 14-year-old Thai HIV-infected girl presented with high-grade fever, multiple painful ulcerated oral lesions, generalized non-pruritic erythrematous skin papules and nodules with central umbilication, and multiple swollen, warm, and tender joints 8 weeks after ART initiation. At that time, her CD4⁺cell count was 7.2% or 39 cells/mm³. On admission, her repeated CD4⁺cell count was 11% or 51 cells/mm³and her plasma HIV-RNA level was < 50 copies/mL. Her skin biopsy showed necrotizing histiocytic granuloma formation with neutrophilic infiltration in the upper and reticular dermis. Tissue sections stained with hematoxylin and eosin (H&E), periodic acid-Schiff (PAS), and Grocott methenamine silver (GMS) stain revealed numerous intracellular and extracellular, round to oval, elongated, thin-walled yeast cells with central septation. The hemoculture, bone marrow culture, and skin culture revealed no growth of fungus or bacteria. Our patient responded well to intravenous amphotericin B followed by oral itraconazole. She fully recovered after 4-month antifungal treatment without evidence of recurrence of disease.</p> <p>Conclusions</p> <p>IRIS from <it>P. marneffei </it>in HIV-infected people is rare. Appropriate recognition and properly treatment is important for a good prognosis.</p

Successful treatment of a child with vascular pythiosis

<p>Abstract</p> <p>Background</p> <p>Human pythiosis is an emerging and life-threatening infectious disease caused by <it>Pythium insidiosum</it>. It occurs primarily in tropical, subtropical and temperate areas of the world, including Thailand. The aim of this report is to present the first pediatric case of typical vascular pythiosis.</p> <p>Case Presentation</p> <p>A 10-year-old boy with underlying β-thalassemia presented with gangrenous ulcers and claudication of the right leg which were unresponsive to antibiotic therapy for 6 weeks. Computerized tomography angiography indicated chronic arterial occlusion involving the right distal external iliac artery and its branches. High-above-knee amputation was urgently done to remove infected arteries and tissues, and to stop disease progression. Antibody to <it>P. insidiosum </it>was detected in a serum sample by the immunoblot and the immunochromatography tests. Fungal culture followed by nucleic sequence analysis was positive for <it>P. insidiosum </it>in the resected iliac arterial tissue. Immunotherapeutic vaccine and antifungal agents were administered. The patient remained well and was discharged after 2 months hospitalization without recurrence of the disease. At the time of this communication he has been symptom-free for 2 years.</p> <p>Conclusions</p> <p>The child presented with the classical manifestations of vascular pythiosis as seen in adult cases. However, because pediatricians were unfamiliar with the disease, diagnosis and surgical treatment were delayed. Both early diagnosis and appropriate surgical and medical treatments are crucial for good prognosis.</p

Immunoassays Based on Penicillium marneffei Mp1p Derived from Pichia pastoris Expression System for Diagnosis of Penicilliosis

BACKGROUND: Penicillium marneffei is a dimorphic fungus endemic in Southeast Asia. It can cause fatal penicilliosis in humans, particularly in HIV-infected people. Diagnosis of this infection is difficult because its clinical manifestations are not distinctive. Specialized laboratory tests are necessary to establish a definitive diagnosis for successful management. We have demonstrated previously that a cell wall mannoprotein Mp1p, abundant in P. marneffei, is a potential biomarker for diagnosis of P. marneffei infections. In the present study, we describe immunoassays based on Mp1p derived from the yeast Pichia pastoris expression system. METHODOLOGY/PRINCIPAL FINDINGS: We generated monoclonal antibodies (MAbs) and rabbit polyclonal antibodies (PAbs) against Mp1p expressed in P. pastoris. Subsequently, we developed two Mp1p antigen capture ELISAs which employed MAbs for both the capture and detecting antibodies (MAb-MAb pair) or PAbs and MAbs as the capture and detecting antibodies (PAbs-MAb pair) respectively. The two Mp1p antigen ELISAs detected Mp1p specifically in cultures of P. marneffei yeast phase at 37-40 degrees C and had no cross-reaction with other tested pathogenic fungi. The sensitivities and specificities of the two antigen assays were found to be 55% (11/20) and 99.6% (538/540) for MAb-MAb Mp1p ELISA, and 75% (15/20) and 99.4% (537/540) for PAbs-MAb Mp1p ELISA performed using 20 sera with culture-confirmed penicilliosis, and 540 control sera from 15 other mycosis patients and 525 healthy donors. Meanwhile, we also developed an anti-Mp1p IgG antibody ELISA with an evaluated sensitivity of 30% (6/20) and a specificity of 98.5% (532/540) using the same sera. Furthermore, combining the results of Mp1p antigen and antibody detection improved the sensitivity of diagnosis to 100% (20/20). CONCLUSIONS/SIGNIFICANCE: Simultaneous detection of antigen and antibody using the immunoassays based on Mp1p derived from P. pastoris greatly improves detection sensitivity. The procedures should be useful for the routine diagnosis of penicilliosis.published_or_final_versio

Protein profiling of the dimorphic, pathogenic fungus, Penicillium marneffei

<p>Abstract</p> <p>Background</p> <p><it>Penicillium marneffei </it>is a pathogenic fungus that afflicts immunocompromised individuals having lived or traveled in Southeast Asia. This species is unique in that it is the only dimorphic member of the genus. Dimorphism results from a process, termed phase transition, which is regulated by temperature of incubation. At room temperature, the fungus grows filamentously (mould phase), but at body temperature (37°C), a uninucleate yeast form develops that reproduces by fission. Formation of the yeast phase appears to be a requisite for pathogenicity. To date, no genes have been identified in <it>P. marneffei </it>that strictly induce mould-to-yeast phase conversion. In an effort to help identify potential gene products associated with morphogenesis, protein profiles were generated from the yeast and mould phases of <it>P. marneffei</it>.</p> <p>Results</p> <p>Whole cell proteins from the early stages of mould and yeast development in <it>P. marneffei </it>were resolved by two-dimensional gel electrophoresis. Selected proteins were recovered and sequenced by capillary-liquid chromatography-nanospray tandem mass spectrometry. Putative identifications were derived by searching available databases for homologous fungal sequences. Proteins found common to both mould and yeast phases included the signal transduction proteins cyclophilin and a RACK1-like ortholog, as well as those related to general metabolism, energy production, and protection from oxygen radicals. Many of the mould-specific proteins identified possessed similar functions. By comparison, proteins exhibiting increased expression during development of the parasitic yeast phase comprised those involved in heat-shock responses, general metabolism, and cell-wall biosynthesis, as well as a small GTPase that regulates nuclear membrane transport and mitotic processes in fungi. The cognate gene encoding the latter protein, designated <it>RanA</it>, was subsequently cloned and characterized. The <it>P. marneffei </it>RanA protein sequence, which contained the signature motif of Ran-GTPases, exhibited 90% homology to homologous <it>Aspergillus </it>proteins.</p> <p>Conclusion</p> <p>This study clearly demonstrates the utility of proteomic approaches to studying dimorphism in <it>P. marneffei</it>. Moreover, this strategy complements and extends current genetic methodologies directed towards understanding the molecular mechanisms of phase transition. Finally, the documented increased levels of RanA expression suggest that cellular development in this fungus involves additional signaling mechanisms than have been previously described in <it>P. marneffei</it>.</p

In silico exploration of Red Sea Bacillus genomes for natural product biosynthetic gene clusters

Background: The increasing spectrum of multidrug-resistant bacteria is a major global public health concern, necessitating discovery of novel antimicrobial agents. Here, members of the genus Bacillus are investigated as a potentially attractive source of novel antibiotics due to their broad spectrum of antimicrobial activities. We specifically focus on a computational analysis of the distinctive biosynthetic potential of Bacillus paralicheniformis strains isolated from the Red Sea, an ecosystem exposed to adverse, highly saline and hot conditions. Results: We report the complete circular and annotated genomes of two Red Sea strains, B. paralicheniformis Bac48 isolated from mangrove mud and B. paralicheniformis Bac84 isolated from microbial mat collected from Rabigh Harbor Lagoon in Saudi Arabia. Comparing the genomes of B. paralicheniformis Bac48 and B. paralicheniformis Bac84 with nine publicly available complete genomes of B. licheniformis and three genomes of B. paralicheniformis, revealed that all of the B. paralicheniformis strains in this study are more enriched in nonribosomal peptides (NRPs). We further report the first computationally identified trans-acyltransferase (trans-AT) nonribosomal peptide synthetase/polyketide synthase (PKS/ NRPS) cluster in strains of this species. Conclusions:B. paralicheniformis species have more genes associated with biosynthesis of antimicrobial bioactive compounds than other previously characterized species of B. licheniformis, which suggests that these species are better potential sources for novel antibiotics. Moreover, the genome of the Red Sea strain B. paralicheniformis Bac48 is more enriched in modular PKS genes compared to B. licheniformis strains and other B. paralicheniformis strains. This may be linked to adaptations that strains surviving in the Red Sea underwent to survive in the relatively hot and saline ecosystems