The virulence of four Sporothrix schenckii isolates was compared in a murine model of sporotrichosis, together with the protein pattern of the yeast cell surface and the capacity to bind the extracellular matrix protein fibronectin. Virulence was determined by the mortality rate, fungal burden and histopathology. Two clinical isolates were more virulent for C57BL/6 mice, but no direct correlation was seen between virulence and the clinical or environmental origin of the isolates. The lowest virulence was observed for an isolate recovered from a patient with meningeal sporotrichosis. Although all isolates could effectively disseminate, the dissemination patterns were not similar. Using flow cytometry analysis, we investigated the interaction of all the strains with fibronectin, and showed that the binding capacity correlated with virulence. Western blot analysis of S. schenckii cell wall extracts revealed positive bands for fibronectin in the range of 37-92 kDa. The 70 kDa adhesin was also recognized by a protective monoclonal antibody raised against a gp70 antigen of S. schenckii (mAb P6E7). Confocal microscopy confirmed the colocalization of fibronectin and mAb P6E7 on the yeast cell surface. To our knowledge, this is the first report identifying adhesins for fibronectin on the surface of this human pathogen.
Chronic kidney disease (CKD) is a silent and poorly known killer. The current concept of CKD is relatively young and uptake by the public, physicians and health authorities is not widespread. Physicians still mix up CKD with chronic kidney insufficiency or failure, For the wider public and health authorities, CKD evokes kidney replacement therapy (KRT). In Spain, the prevalence of KRT is 0.13%. Thus, health authorities may consider CKD a non-issue: very few persons eventually need KRT and, for those in whom kidneys fail, the problem is “solved” by dialysis or kidney transplantation. However, KRT is the tip of the iceberg in the burden of CKD. The main burden of CKD is accelerated aging and premature death. The cut-off points for kidney function and kidney damage indexes that define CKD also mark an increased risk for all-cause premature death. CKD is the most prevalent risk factor for lethal COVID-19 and the factor that most increases the risk of death in COVID-19, after old age. Men and women undergoing KRT still have an annual mortality which is 10- o 100-fold higher than similar age peers, and life expectancy is shortened by around 40 years for young persons on dialysis and by 15 years for young persons with a functioning kidney graft. CKD is expected to become the fifth global cause of death by 2040 and the second cause of death in Spain before the end of the century, a time when 1 in 4 Spaniards will have CKD. However, by 2022, CKD will become the only top-15 global predicted cause of death that is not supported by a dedicated well-funded CIBER network research structure in Spain. Realizing the underestimation of the CKD burden of disease by health authorities, the Decade of the Kidney initiative for 2020-2030 was launched by the American Association of Kidney Patients (AAKP) and the European Kidney Health Alliance (EKHA). Leading Spanish kidney researchers grouped in the kidney collaborative research network REDINREN have now applied for the RICORS call of collaborative research in Spain with the support of the Spanish Society of Nephrology, ALCER and ONT: RICORS2040 aims to prevent the dire predictions for the global 2040 burden of CKD from becoming true.
This is a first report in Mexico of the presence of antibodies against respiratory syncytial virus (RSV) and parainfluenza-3 virus in Mexican sheep in different productive stages. We determine the association of serological positivity with age and production system, and obtain molecular evidence of infection by both virus. RSV prevalence in adult sheep was 47% (49/105) at the tropic and 64% (63/99) at the uplands. A significant difference in RSV seropositivity between animals from the tropic and the uplands was observed (P \ 0.05). Seropositivity correlated with production system (P = 0.003, OR = 2.042), with a risk of showing antibodies was 2.042 times higher in sheep under an extensive production system. A significant difference in PI3V seropositivity between animals from either provenance (P = 0.017, OR = 0.475) were also found, with a risk of showing antibodies 0.475 times higher in sheep under an extensive production system. Genetic material from RSV and PI3V was identified by RT-PCR in nasal swab samples from clinically healthy lambs and confirmed by sequencing and phylogenetic analysis. Serological results show that sheep are susceptible to infection by both viruses, and molecular results suggest that the identified antibodies are result of natural infections and reinfections.
Melanin is a complex polymer widely distributed in nature and has been described as an important virulence factor in several pathogenic fungi, including Sporothrix schenckii. The aim of the present work was to investigate the presence of melanin on the surface of S. schenckii yeast cells which showed differences in their virulence depending on the culture conditions under which they were grown. Yeast cells were cultivated in brain heart infusion (BHI) broth from Difco and Oxoid. BHI from these two vendors are different in their brain and heart infusion contents. Yeasts cultivated in the medium containing the higher brain infusion content were highly virulent as ascertained by the mice mortality rate, CFU and histopathology. Transmission electron microscopy revealed a higher expression of electron dense granules on the fungal cell wall of the most virulent yeast cells. Flow cytometry analysis, with anti-melanin antibodies, confirmed that this pigment was melanin. Furthermore, spectrophotometric analysis showed a higher concentration of this polymer on NaOH and cell wall extracts of the most virulent yeast cells. These results suggest that differences in the relative content of brain and heart infusion in the culture medium modulated melanin expression on the surface of S. schenckii yeast cells and, as a consequence, virulence. A new pathway of melanin biosynthesis in S. schenckii is proposed which involves the use of phenolic compounds from rich brain medium as melanin substrate.
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