Javier Capilla

The velvet complex governs mycotoxin production and virulence of Fusarium oxysporum on plant and mammalian hosts

Fungal pathogens provoke devastating losses in agricultural production, contaminate food with mycotoxins and give rise to life‐threatening infections in humans. The soil‐borne ascomycete Fusarium oxysporum attacks over 100 different crops and can cause systemic fusariosis in immunocompromised individuals. Here we functionally characterized VeA, VelB, VelC and LaeA, four components of the velvet protein complex which regulates fungal development and secondary metabolism. Deletion of veA, velB and to a minor extent velC caused a derepression of conidiation as well as alterations in the shape and size of microconidia. VeA and LaeA were required for full virulence of F. oxysporum on tomato plants and on immunodepressed mice. A critical contribution of velvet consists in promoting chromatin accessibility and expression of the biosynthetic gene cluster for beauvericin, a depsipeptide mycotoxin that functions as a virulence determinant. These results reveal a conserved role of the velvet complex during fungal infection on plants and mammals.

HapX-Mediated Iron Homeostasis Is Essential for Rhizosphere Competence and Virulence of the Soilborne Pathogen Fusarium oxysporum

This study shows that the bZIP protein HapX, a key regulator of the iron response, is required for rhizosphere competence of the vascular wilt fungus Fusarium oxysporum against soil-inhabiting bacteria and for virulence on tomato (Solanum lycopersicum) plants and immunodepressed mice, establishing a conserved role for HapX-mediated iron homeostasis in fungal infection of plants and mammals. Soilborne fungal pathogens cause devastating yield losses and are highly persistent and difficult to control. During the infection process, these organisms must cope with limited availability of iron. Here we show that the bZIP protein HapX functions as a key regulator of iron homeostasis and virulence in the vascular wilt fungus Fusarium oxysporum. Deletion of hapX does not affect iron uptake but causes derepression of genes involved in iron-consuming pathways, leading to impaired growth under iron-depleted conditions. F. oxysporum strains lacking HapX are reduced in their capacity to invade and kill tomato (Solanum lycopersicum) plants and immunodepressed mice. The virulence defect of ΔhapX on tomato plants is exacerbated by coinoculation of roots with a biocontrol strain of Pseudomonas putida, but not with a siderophore-deficient mutant, indicating that HapX contributes to iron competition of F. oxysporum in the tomato rhizosphere. These results establish a conserved role for HapX-mediated iron homeostasis in fungal infection of plants and mammals.

Efficacy of Voriconazole in Treatment of Systemic Scedosporiosis in Neutropenic Mice

ABSTRACT We have evaluated the efficacy of voriconazole (VRC) in a murine model of systemic infection by Scedosporium apiospermum. The survival of mice treated with VRC at 5, 20, or 40 mg/kg/day was greater than that of the control group (P ≤ 0.0009). VRC reduced the tissue burden in the spleen and brain (P < 0.001 in both organs) in comparison with that of the control group.

Animal models: an important tool in mycology

Abstract Animal models of fungal infections are, and will remain, a key tool in the advancement of the medical mycology. Many different types of animal models of fungal infection have been developed, with murine models the most frequently used, for studies of pathogenesis, virulence, immunology, diagnosis, and therapy. The ability to control numerous variables in performing the model allows us to mimic human disease states and quantitatively monitor the course of the disease. However, no single model can answer all questions and different animal species or different routes of infection can show somewhat different results. Thus, the choice of which animal model to use must be made carefully, addressing issues of the type of human disease to mimic, the parameters to follow and collection of the appropriate data to answer those questions being asked. This review addresses a variety of uses for animal models in medical mycology. It focuses on the most clinically important diseases affecting humans and cites various examples of the different types of studies that have been performed. Overall, animal models of fungal infection will continue to be valuable tools in addressing questions concerning fungal infections and contribute to our deeper understanding of how these infections occur, progress and can be controlled and eliminated.

Two Cases of Subcutaneous Infection Due to Phaeoacremonium spp.

ABSTRACT We describe two cases in Brazil of human subcutaneous infections due to Phaeoacremonium spp. The first case was caused by Phaeoacremoniumaleophilum. The patient presented with a unique fistulized nodule on the left ankle. The fungus was detected by direct microscopic examination and was isolated repeatedly from material collected from the lesion. This is the first reported case of human infection caused by this fungus. The second case was caused by Phaeoacremoniumrubrigenum. The patient presented with multiple nodules around the left ankle and foot. The fungus was detected by direct examination of pus and histological sections of the nodules. It was repeatedly isolated from the clinical specimens. This is the second reported case of human infection caused by this species.

In Vitro Antifungal Activities of the New Triazole UR-9825 against Clinically Important Filamentous Fungi

ABSTRACT We used a modified reference microdilution method (the M-38P method) to evaluate the in vitro activities of the new triazole UR-9825 in comparison with those of amphotericin B against 77 strains of opportunistic filamentous fungi. UR-9825 was clearly more active than amphotericin B against all fungi except Fusarium solaniand Scytalidium spp. Notably, UR-9825 had low MICs forAspergillus fumigatus and Paecilomyces lilacinus (MICs at which 90% of isolates are inhibited, 0.125 μg/ml for both species).

Efficacy of Albaconazole (UR-9825) in Treatment of Disseminated Scedosporium prolificans Infection in Rabbits

ABSTRACT There are no effective therapeutics for treating invasive Scedosporium prolificans infections. Doses of 15, 25, and 50 mg/kg of body weight/day for the new triazole albaconazole (ABC) were evaluated in an immunocompetent rabbit model of systemic infection with this mold. Treatments were begun 1 day after challenge and given for 10 days. ABC at any dose was more effective than amphotericin B (AMB) at 0.8 mg/kg/day at clearing S. prolificans from tissue (P < 0.007). The percentages of survival at 25 mg of ABC/kg/day were similar to those obtained with AMB. Rabbits showed 100% survival when they were treated with 50 mg of ABC per kg (P < 0.0001 versus control group), and only this dosage was able to reduce tissue burden significantly in the five organs studied, i.e., spleen, kidneys, liver, lungs, and brain.

Saccharomyces cerevisiae as a vaccine against coccidioidomycosis

Disseminated coccidioidomycosis is a life-threatening infection. In these studies, we examined protection against systemic murine coccidioidomycosis by vaccination with heat-killed Saccharomyces cerevisiae (HKY). CD-1 mice received HKY subcutaneously or by oral gavage with or without adjuvants once weekly beginning 3 or 4 weeks prior to infection; oral live Saccharomyces was also studied. All HKY sc regimens were equivalent, prolonging survival (P<or=0.005) and reducing fungal burden versus controls. Oral live Saccharomyces, but not HKY, prolonged survival (P=0.03), but did not reduce fungal burden. Survival of mice given HKY was equivalent to vaccination with formalin-killed spherules, but inferior in reduction of fungal burden. HKY was superior to a successful recombinant vaccine, PRA plus adjuvant. This novel heterologous protection afforded by HKY vaccination offers a new approach to a vaccine against coccidioidomycosis.

In Vitro Interactions of Approved and Novel Drugs against Paecilomyces spp

ABSTRACT We have evaluated the in vitro activity of 15 combinations of antifungal drugs (amphotericin B, itraconazole, voriconazole, albaconazole, ravuconazole, terbinafine, and micafungin) against four isolates of Paecilomyces variotii and three of P. lilacinus. The interaction of terbinafine with the four azoles was synergistic for 53% of the combinations, while the interactions of both amphotericin B and micafungin with the rest of antifungal agents were mainly indifferent.

In Vitro Antifungal Susceptibilities of Uncommon Basidiomycetous Yeasts

ABSTRACT The in vitro activities of eight antifungal drugs against 50 isolates of basidiomycetous yeasts were determined by a microdilution method. In general fluconazole and micafungin were inactive. Terbinafine was active only against Sporobolomyces salmonicolor. The activities of the other antifungals were variable and depended on the species tested. The new triazoles showed the lowest MICs, but amphotericin B and itraconazole were the only drugs active against Cryptococcus albidus.