Functional selection of protease inhibitory antibodies.

Critical for diverse biological processes, proteases represent one of the largest families of pharmaceutical targets. To inhibit pathogenic proteases with desired selectivity, monoclonal antibodies (mAbs) hold great promise as research tools and therapeutic agents. However, identification of mAbs with inhibitory functions is challenging because current antibody discovery methods rely on binding rather than inhibition. This study developed a highly efficient selection method for protease inhibitory mAbs by coexpressing 3 recombinant proteins in the periplasmic space of Escherichia coli-an antibody clone, a protease of interest, and a ß-lactamase modified by insertion of a protease cleavable peptide sequence. During functional selection, inhibitory antibodies prevent the protease from cleaving the modified ß-lactamase, thereby allowing the cell to survive in the presence of ampicillin. Using this method to select from synthetic human antibody libraries, we isolated panels of mAbs inhibiting 5 targets of 4 main protease classes: matrix metalloproteinases (MMP-14, a predominant target in metastasis; MMP-9, in neuropathic pain), ß-secretase 1 (BACE-1, an aspartic protease in Alzheimer's disease), cathepsin B (a cysteine protease in cancer), and Alp2 (a serine protease in aspergillosis). Notably, 37 of 41 identified binders were inhibitory. Isolated mAb inhibitors exhibited nanomolar potency, exclusive selectivity, excellent proteolytic stability, and desired biological functions. Particularly, anti-Alp2 Fab A4A1 had a binding affinity of 11 nM and inhibition potency of 14 nM, anti-BACE1 IgG B2B2 reduced amyloid beta (Aß40) production by 80% in cellular assays, and IgG L13 inhibited MMP-9 but not MMP-2/-12/-14 and significantly relieved neuropathic pain development in mice.

Congenital bronchial atresia complicated by a lung abscess due to Aspergillus fumigatus: a case report.

BACKGROUND: Congenital bronchial atresia is a rare pulmonary abnormality characterized by the disrupted communication between the central and the peripheral bronchus and is typically asymptomatic. Although it can be symptomatic especially when infections occur in the involved areas, fungal infections are rare complications in patients with bronchial atresia. We report a case of congenital bronchial atresia complicated by a fungal infection. CASE PRESENTATION: A 30-year-old man with no previous history of immune dysfunction was brought to a nearby hospital and diagnosed with a left lung abscess. Although antimicrobial treatment was administered, it was ineffective, and he was transferred to our hospital. Since diagnostic imaging findings and bronchoscopy suggested congenital bronchial atresia and a fungal infection, he was treated with voriconazole and surgical resection was subsequently performed. A tissue culture detected Aspergillus fumigatus and histopathological findings were compatible with bronchial atresia. After discharge, he remained well and voriconazole was discontinued 5 months after the initiation of therapy. CONCLUSION: Bronchial atresia is a rare disease that is seldom complicated by a fungal infection, which is also a rare complication; however, physicians should consider fungal infections in patients with bronchial atresia who present with infections resistant to antimicrobial treatment.

Lenticular fungal infection caused by Aspergillus in a patient with traumatic corneal laceration: a case report.

BACKGROUND: To report a case of lenticular infection caused by Aspergillus, which was diagnosed 13 weeks after traumatic corneal laceration. CASE PRESENTATION: A 60-year-old woman presented with traumatic corneal laceration including anterior lens capsule rupture and traumatic cataract after being hit with a chestnut in the right eye. There were multiple injuries due to tiny thorns of the chestnut, including the conjunctiva, sclera, cornea, and anterior lens capsule. But no visible foreign body was detected by slit-lamp examination. Topical corticosteroid was prescribed to resolve the conjunctival inflammation induced by the thorns of chestnut, which could have caused persistent irritation. As conjunctival injection and edema being decreased during outpatient clinical follow-up, embedded conjunctival foreign body was detected and surgically removed (1st surgery). Approximately 10 weeks after the trauma, severe inflammation of the anterior segment accompanied with hypopyon developed suddenly and at the same time embedded scleral foreign body was revealed. After removal of scleral foreign body (2nd surgery), unspecified mold species was cultured from the scleral foreign body in SDA (Sabouraud dextrose agar) plate. Suspicious corneal foreign body was removed as 3rd surgery and phacoemulsification of traumatic cataract was planned as 4th surgery. Aspergillus was finally detected from removed anterior capsule and fibrotic membrane during the operation. Fungal infection resolved successfully after administration of topical (1% voriconazole and 5% natamycin) and systemic (fluconazole) antifungal agents and phacoemulsification of traumatic cataract. CONCLUSION: Chestnut thorns can damage multiple ocular tissues simultaneously. Lens capsular rupture could result in fungal inoculation and lead to delayed lenticular fungal infection with complicated cataract formation. In cases of ocular trauma due to organic substances such as thorns and branches, the possibility of fungal infection should be considered.

Microbial glycoside hydrolases as antibiofilm agents with cross-kingdom activity.

Galactosaminogalactan and Pel are cationic heteropolysaccharides produced by the opportunistic pathogens Aspergillus fumigatus and Pseudomonas aeruginosa, respectively. These exopolysaccharides both contain 1,4-linked N-acetyl-d-galactosamine and play an important role in biofilm formation by these organisms. Proteins containing glycoside hydrolase domains have recently been identified within the biosynthetic pathway of each exopolysaccharide. Recombinant hydrolase domains from these proteins (Sph3h from A. fumigatus and PelAh from P. aeruginosa) were found to degrade their respective polysaccharides in vitro. We therefore hypothesized that these glycoside hydrolases could exhibit antibiofilm activity and, further, given the chemical similarity between galactosaminogalactan and Pel, that they might display cross-species activity. Treatment of A. fumigatus with Sph3h disrupted A. fumigatus biofilms with an EC50 of 0.4 nM. PelAh treatment also disrupted preformed A. fumigatus biofilms with EC50 values similar to those obtained for Sph3h In contrast, Sph3h was unable to disrupt P. aeruginosa Pel-based biofilms, despite being able to bind to the exopolysaccharide. Treatment of A. fumigatus hyphae with either Sph3h or PelAh significantly enhanced the activity of the antifungals posaconazole, amphotericin B, and caspofungin, likely through increasing antifungal penetration of hyphae. Both enzymes were noncytotoxic and protected A549 pulmonary epithelial cells from A. fumigatus-induced cell damage for up to 24 h. Intratracheal administration of Sph3h was well tolerated and reduced pulmonary fungal burden in a neutropenic mouse model of invasive aspergillosis. These findings suggest that glycoside hydrolases can exhibit activity against diverse microorganisms and may be useful as therapeutic agents by degrading biofilms and attenuating virulence.

Invasive mould infections in solid organ transplant patients: modifiers and indicators of disease and treatment response.

PURPOSE: Invasive mould infections, in particular invasive aspergillosis (IA), are comparatively frequent complications of immunosuppression in patients undergoing solid organ transplantation (SOT). Guidelines provide recommendations as to the procedures to be carried out to diagnose and treat IA, but only limited advice for SOT recipients. METHODS: Literature review and expert consensus summarising the existing evidence related to prophylaxis, diagnosis, treatment and assessment of response to IA and infections by Mucorales in SOT patients RESULTS: Response to therapy should be assessed early and at regular intervals. No indications of improvement should lead to a prompt change of the antifungal treatment, to account for possible infections by Mucorales or other moulds such as Scedosporium. Imaging techniques, especially CT scan and possibly angiography carried out at regular intervals during early and long-term follow-up and coupled with a careful clinical diagnostic workout, should be evaluated as diagnostic tools and outcome predictors, and standardised to improve therapy monitoring. The role of biomarkers such as the galactomannan test and PCR, as well as selected inflammation parameters, has not yet been definitively assessed in the SOT population and needs to be studied further. The therapeutic workup should consider a reduction of immunosuppressive therapy. CONCLUSIONS: The role of immunosuppression and immune tolerance mechanisms in the response to invasive fungal infection treatment is an important factor in the SOT population and should not be underestimated. The choice of the antifungal should consider not only their toxicity but also their effects on the immune system, two features that are intertwined.

Successful Treatment of Severe Aspergillosis with Isavuconazole Therapy after Allogeneic Stem Cell Transplantation.

Invasive fungal infections are one of the main infectious complications in allogeneic stem cell transplantation (SCT). Triazoles (voriconazole, posaconazole) are the main prophylactic and therapeutic options for the treatment of invasive aspergillosis. However, pharmacological interactions and hepatotoxicity limit its use. Isavuconazole (ISV) is a recently approved azole with a promising interaction and safety profile. We present a case with invasive aspergillosis in the post-allogeneic SCT setting in a critically ill patient with severe multiorgan failure due to veno-occlusive disease. The patient was treated with ISV and B amphotericin during severe kidney and liver failure and multiple immunosuppressants, without significant drug-related toxicity and with favorable outcome. The interaction and safety profile of ISV is discussed along the reported experience. ISV can be an effective salvage therapy even in complex clinical situations with multiple potential interactions.

Aspergillus aortitis & aortic valve endocarditis after coronary surgery.

The authors report a case of Aspergillus aortitis and aortic valve endocarditis that developed after coronary artery bypass surgery resulting in recurrent, embolic, bilateral lower extremity ischemia. This necessitated multiple lower extremity embolectomies followed by redo-sternotomy, extensive annular debridement, root reconstruction with a modified Bentall technique, and hemiarch replacement. This case highlights the challenges in diagnosis and management of this rare disease entity and some of its devastating complications.

[Customised infectiology - Immunogenetics]. / Infectiologie sur mesure - 1.Immunogénétique des maladies infectieuses†: premiers pas.

Recent discoveries in innate immunity together with improvements in the analysis of the human genome have led to the identification of factors that make certain individuals more susceptible to infections than other. We know understand why herpes simplex virus I, a virus with a minor burden in most individuals, is responsible for devastating encephalitis in children unable to detect primo-infection of neural cells. A growing number of patients are treated with immunosuppressive drugs in the field of oncology, organ transplantation and immunology. In such patients, opportunistic infections such invasive aspergillosis are clearly associated with genetic polymorphisms. Medical immune suppression represents a possible model for personalized approaches, in which infections could be prevented by individualized prophylactic strategies based on genetic testing.

Les progrès de la connaissance du système immunitaire inné et des techniques d'analyse du génome humain ont permis d'identifier des facteurs qui rendent certains individus susceptibles aux agents infectieux. C'est ainsi que l'on comprend depuis quelques années pourquoi le virus de l'herpès simplex I peut causer des encéphalites dévastatrices chez des enfants dont l'immunité est incapable de détecter la primo-infection. De plus en plus de patients subissent des traitements immunosuppresseurs dans le domaine de l'oncologie, des greffes d'organes ou de l'immunologie. Chez ces patients, certaines infections opportunistes, comme l'aspergillose pulmonaire invasive, sont clairement associées à des polymorphismes génétiques. L'immunosuppression Med représente un modèle possible d'infectiologie personnalisée, où les infections pourraient être prévenues par des prophylaxies individualisées, basées sur des tests génétiques.

Adjunctive interferon-γ immunotherapy in a pediatric case of Aspergillus terreus infection.

Aspergillus terreus causes invasive aspergillosis (IA) in immunocompromised patients. Treatment is complicated by intrinsic resistance to amphotericin B and thereby contributing to a high mortality. Therefore, we conducted in vitro studies to investigate the effectivity of adjunctive recombinant interferon-γ immunotherapy. We describe a pediatric patient with A. terreus IA who received adjunctive recombinant interferon-γ (rIFNγ) immunotherapy. In vitro studies were conducted to investigate the capacity of rIFNγ to improve antifungal host defense in terms of fungal killing ability and the release of pro-inflammatory cytokines in cells of the patient as well as healthy controls. An 8-year-old female pediatric patient with leukemia developed A. terreus IA. She clinically deteriorated and had high serum galactomannan levels despite broad antifungal therapy. Therefore, adjunctive immune stimulatory therapy with rIFNγ was initiated. After 3 weeks of treatment, galactomannan levels decreased and the patient clinically showed improvement. Addition of rIFNγ boosted the capacity of monocytes of healthy volunteers to mount TNFα and IL-1ß cytokine responses to Escherichia coli LPS, and increased TNFα response to both A. terreus and Aspergillus fumigatus. Monocytes isolated from the patient's blood demonstrated a similar augmented cytokine induction in response to rIFNγ. In addition, rIFNγ increased the capacity of monocytes from healthy volunteers as well as monocytes from the patient to kill A. terreus spores. Adjuvant immunotherapy with rIFNγ might be a promising additional treatment strategy that could be used to improve outcome in patients with refractory invasive A. terreus infections or other resistant invasive Aspergillus infections.

Primary cutaneous aspergillosis at the site of cyanoacrylate skin adhesive in a neonate.

Primary cutaneous aspergillosis is a rare but potentially life-threatening disease. We present the case of a premature infant who developed primary cutaneous aspergillosis with Aspergillus niger at the site of a skin abrasion that had been treated with a purple-colored cyanoacrylate product. The infection was treated successfully with gentle debridement of the cyanoacrylate product, followed by intravenous voriconazole and topical fluconazole. To our knowledge, this is the first reported case of primary cutaneous aspergillosis occurring at the site of cyanoacrylate-based skin adhesive.

Fungal osteomyelitis in a patient with chronic granulomatous disease: Case report and review of the literature.

Chronic granulomatous disease (CGD) is the most common of the primary immunodeficiency in children. It is caused by single gene defect resulting in dysfunctional nicotinamide adenine dineucleotide phosphate (NADPH) oxidase complex causing recurrent bacterial and fungal infections. Here we present the case of a 9 year old boy who was a known case of CGD since three years of age. He presented with recent history of fever, left sided pain in the scapular region and difficulty in breathing. Chest imaging revealed developing left upper lobe consolidation and erosion of the 3rd posterior rib. The child underwent video assisted thoracoscopic surgery (VATS) and biopsy of the lesion. Histopathology revealed fungal hyphae which were confirmed to be Aspergillus nidulans on staining. He was successfully treated with voriconazole therapy. We will also review the literature on fungal osteomyelitis in CGD patients.

ECIL-6 guidelines for the treatment of invasive candidiasis, aspergillosis and mucormycosis in leukemia and hematopoietic stem cell transplant patients.

The European Conference on Infections in Leukemia (ECIL) provides recommendations for diagnostic strategies and prophylactic, pre-emptive or targeted therapy strategies for various types of infection in patients with hematologic malignancies or hematopoietic stem cell transplantation recipients. Meetings are held every two years since 2005 and evidence-based recommendations are elaborated after evaluation of the literature and discussion among specialists of nearly all European countries. In this manuscript, the ECIL group presents the 2015-update of the recommendations for the targeted treatment of invasive candidiasis, aspergillosis and mucormycosis. Current data now allow a very strong recommendation in favor of echinocandins for first-line therapy of candidemia irrespective of the underlying predisposing factors. Anidulafungin has been given the same grading as the other echinocandins for hemato-oncological patients. The beneficial role of catheter removal in candidemia is strengthened. Aspergillus guidelines now recommend the use of either voriconazole or isavuconazole for first-line treatment of invasive aspergillosis, while first-line combination antifungal therapy is not routinely recommended. As only few new data were published since the last ECIL guidelines, no major changes were made to mucormycosis recommendations.

A CONSORT analysis of randomised controlled trials for the treatment of invasive aspergillosis.

There is no assessment of the reporting quality of antifungal randomized, controlled trials (RCT), upon which guidelines for the treatment of invasive aspergillosis (IA) in patients with hematological malignancy are based. Trial reports were identified through Trip, Cochrane, Medline, and Embase database searches. Report quality was assessed using the 25-item CONSORT checklist and a rating scale of 1 (strongly disagree) to 4 (strongly agree). The primary endpoint was quality as assessed by mean group-scores among papers published at the time of the most recent IA treatment guidelines. Seven RCTs were identified for analysis. Overall mean group-score for all seven papers was 2.44 (out of a total of four). There were significant differences between publications regarding overall reporting quality (P < .001) and specifically for the Methods and Results (P = .004 and P = .010, respectively), which best reflect data quality. The Cornely trial report achieved the highest mean group-score overall (3.15 ± 0.93; 95% CI, 2.82, 3.47), as well as for Methods (3.36) and Results (3.40). Mean group scores also showed that it was of significantly higher overall quality than the other six publications (P-value range; .012 to <.001), and of higher quality for Methods than five publications (P-value range; .013 to <.001). Incorporating this CONSORT analysis into the evidence-based grading systems in North American (IDSA), European (ECIL and ESCMID) IA guidelines could alter the value placed on these RCTs, thereby impacting on clinical recommendations.

The anti-Aspergillus drug pipeline: Is the glass half full or empty?

Aspergillosis has emerged as important human mycoses, in view of the ever expanding population at risk. The emergence of resistance to the most commonly used drugs for aspergillosis, the azoles, the mediocre activity, and frequent toxicity of the current antifungal armamentarium, support the need for development of novel antifungals for treatment of this disease. In this minireview, we describe recent efforts by small drug companies and University research labs to develop novel therapies for invasive aspergillus infections. We specifically discuss four small-molecule antifungals (T-2307, E1210/APX001, ASP2397, and F901318) with novel modes-of-action, which are currently entering phase I clinical trials. In addition, we provide a nonexhaustive discussion of some interesting, yet early developments in the quest for improved therapeutic strategies such as (i) novel formulations of amphotericin B including AMB nanoparticle suspensions and AMB-arabinogalactan or AMB-PEG conjugates that show low toxicity and high efficacy in preclinical animal models, (ii) repurposed drugs that synergize with existing antifungals (clozafimine, trichostatin A, MGCD290, geldanamycin, tacrolimus, cyclosporin), (iii) natural products (psoriasin, humidimycin), and (iv) immunotherapy using adoptive transfer of activated immune cells with antifungal activity. We argue that despite the plethora of candidates, the extremely low success rates of drug development leading to clinically useful drugs reinforces the need for continued clinical reliance on mainstream antifungals and their improved derivatives.

Aspergillus arthritis: analysis of clinical manifestations, diagnosis, and treatment of 31 reported cases.

Aspergillus arthritis is a debilitating form of invasive aspergillosis. Little is known about its epidemiology, clinical manifestations, laboratory features, treatment, and prognosis. Cases of Aspergillus arthritis were reviewed in the English literature from 1967 through 2015 for variables of arthritis with Aspergillus spp. recovered from joint and/or adjacent bone, underlying conditions, symptoms, signs, inflammatory biomarkers, diagnostic imaging, management, and outcome. Among 31 evaluable cases, 87% were males and 13% pediatric. Median age was 50 y (range 1-83 y). Seventeen (55%) patients were immunosuppressed with such conditions as hematological malignancies (26%), corticosteroids (39%), and/or transplantation (26%). Approximately one-half (52%) of patients had hematogenous seeding of the joint, and more than 80% had de novo infection with no prior antifungal therapy. Oligoarticular infection (2-3 joints) occurred in 45% and contiguous osteomyelitis was present in 61%. Clinical manifestations included pain (87%), edema (26%), and limited function (23%), with knees (35%), intervertebral discs (26%), and hips (16%) being most commonly infected. Aspergillus fumigatus constituted 77% of cases followed by Aspergillus flavus in 13%, Aspergillus niger in 3%, and not specified in 7%. Median ESR was 90 mm/hr and median CRP was 3.6 mg/dl. Median synovial fluid WBC was 17,200/µL (7,300-128,000) with 72% PMNs (range 61-92). Osteolysis occurred in 35%, and soft-tissue extension 47%. Nineteen patients (61%) were managed with combined medical and surgical therapy, 10 (32%) with medical therapy only, and 2 (6%) surgery only. Amphotericin B and itraconazole were the most frequently used agents with median duration of therapy of 219 days (range 30-545). Surgical interventions included debridement in 61%, drainage 19%, and amputation 6%. Complete or partial response was achieved in 71% and relapse occurred in 16%. Medical therapy was reinstituted with successful outcome in these patients. Overall survival was 65%. Aspergillus arthritis mainly develops as a de novo infection involving knees and intervertebral disks in immunocompromised patients with localizing symptoms. Contiguous osteomyelitis is frequently observed. Diagnosis is established by synovial fluid culture. Aspergillus arthritis is therapeutically challenging with most patients undergoing surgery and protracted antifungal therapy.

Fifty-one cases of fungal arteritis after kidney transplantation: A case report and review of the literature.

Fungal arteritis affecting graft arteries is a rare but life-threatening complication in kidney transplantation (KT). Here, we report the case of a patient with Aspergillus arteritis who experienced renal artery rupture 8 days after KT. We also reviewed 50 other reported cases of fungal arteritis after KT. We found that fungal contamination can occur during kidney graft harvest, preservation, and/or transplantation. Typically, early diagnosis, timely antifungal treatment, and emergency surgery seem crucial for avoiding life-threatening vascular complications.

Bioengineering T cells to target carbohydrate to treat opportunistic fungal infection.

Clinical-grade T cells are genetically modified ex vivo to express chimeric antigen receptors (CARs) to redirect their specificity to target tumor-associated antigens in vivo. We now have developed this molecular strategy to render cytotoxic T cells specific for fungi. We adapted the pattern-recognition receptor Dectin-1 to activate T cells via chimeric CD28 and CD3-ζ (designated "D-CAR") upon binding with carbohydrate in the cell wall of Aspergillus germlings. T cells genetically modified with the Sleeping Beauty system to express D-CAR stably were propagated selectively on artificial activating and propagating cells using an approach similar to that approved by the Food and Drug Administration for manufacturing CD19-specific CAR(+) T cells for clinical trials. The D-CAR(+) T cells exhibited specificity for ß-glucan which led to damage and inhibition of hyphal growth of Aspergillus in vitro and in vivo. Treatment of D-CAR(+) T cells with steroids did not compromise antifungal activity significantly. These data support the targeting of carbohydrate antigens by CAR(+) T cells and provide a clinically appealing strategy to enhance immunity for opportunistic fungal infections using T-cell gene therapy.

Cerebral aspergillosis: a retrospective analysis of eight cases.

PURPOSE: Aspergillosis of the central nervous system is very rare. However with recent increases in the use of immunosuppressive agents and antibiotics, its incidence is increasing. We evaluated the demographics, clinical manifestations, laboratory findings, diagnosis, underlying conditions, treatment regimens and outcomes of patients with cerebral aspergillosis (CA). METHODS: We retrospectively reviewed data from eight patients with CA hospitalized at a Chinese general hospital from 1 January 2005 to 30 September 2015. RESULTS: Common clinical manifestations included headache and cranial nerve involvement. Four patients underwent biopsy and were pathologically diagnosed with Aspergillus hyphae. One patient was proved to have Aspergillus infection via autopsy. One patient had positive cerebrospinal fluid fungal cultures. The lesion locations were: the cavernous sinus (n = 5, 62.5%), frontal lobe (n = 1, 12.5%), temporosphenoid lobe (n = 1, 12.5%) and cerebellum (n = 1, 12.5%). At the end of follow-up, three patients were cured and five patients had died (mortality rate, 62.5%). CONCLUSIONS: Most patients with CA had no significant immunosuppression-related conditions in our study. Aspergillus spp. can infect the central nervous system through several pathways and CA has an atypical clinical manifestation. The use of local tissue puncture, surgery or other invasive means to obtain diseased tissue containing higher levels of Aspergillus, followed by culture or histological examination, can contribute to an early diagnosis of CA and timely therapeutic intervention. The prognosis of CA is poor, but early and adequate use of antifungal drugs with high transfer across the blood-brain barrier and radical surgery to remove lesions can improve the survival rate.

Aspergillus flavus Keratitis: Experience of a Tertiary Eye Clinic in Turkey.

We investigated the clinical and mycological characteristics of four cases of mycotic keratitis caused by Aspergillus flavus that occurred from July 2014 to May 2015 at Çukurova University Hospital, Adana, Turkey. In a 10-month period, a total of 64 corneal smear/scrapings were examined from patients with suspected mycotic keratitis. Fungal cultures were positive in six of these patients, indicating a 9.4% incidence of mycotic keratitis in this region, including four cases of A. flavus and two cases of Fusarium spp. The predisposing factors, clinical presentation, and success of the therapeutic approaches were further evaluated. For all cases, topical voriconazole was the first choice of treatment. Surgical procedures were required to control infection in 3 of the 4 cases, including intrastromal voriconazole injection for two cases and keratoplasty for one case. Predisposing factors included trauma (two cases, 50%), contact lens use (one case, 25%), and previous ocular surgery (one case, 25%). The clinical presentations also differed, including a well-limited ulcer (one case), an ulcer with an irregular feathery margin (one case), and ulcers with satellite lesions (two cases). The mean duration between the time of presentation and definitive diagnosis by culture was 14 days (8-25 days). We observed that A. flavus keratitis can present with different underlying factors and clinical conditions. A combination of antifungal therapy and supportive surgical intervention may resolve infections caused by A. flavus in the cornea.

Mitochondrial dynamics in the pathogenic mold Aspergillus fumigatus: therapeutic and evolutionary implications.

Mitochondria within eukaryotic cells continuously fuse and divide. This phenomenon is called mitochondrial dynamics and crucial for mitochondrial function and integrity. We performed a comprehensive analysis of mitochondrial dynamics in the pathogenic mold Aspergillus fumigatus. Phenotypic characterization of respective mutants revealed the general essentiality of mitochondrial fusion for mitochondrial genome maintenance and the mold's viability. Surprisingly, it turned out that the mitochondrial rhomboid protease Pcp1 and its processing product, s-Mgm,1 which are crucial for fusion in yeast, are dispensable for fusion, mtDNA maintenance and viability in A. fumigatus. In contrast, mitochondrial fission mutants show drastically reduced growth and sporulation rates and increased heat susceptibility. However, reliable inheritance of mitochondria to newly formed conidia is ensured. Strikingly, mitochondrial fission mutants show a significant and growth condition-dependent increase in azole resistance. Parallel disruption of fusion in a fission mutant partially rescues growth and sporulation defects and further increases the azole resistance phenotype. Taken together, our results indicate an emerging dispensability of the mitochondrial rhomboid protease function in mitochondrial fusion, the suitability of mitochondrial fusion machinery as antifungal target and the involvement of mitochondrial dynamics in azole susceptibility.