Role of Protein Mannosylation in the Candida tropicalis-Host Interaction

Mannans are components of the fungal wall attached to proteins via N- or O-linkages. In Candida albicans, Och1 is an α1,6-mannosyltransferase that adds the first mannose unit to the N-linked mannan outer chain; whereas Pmr1 is an ion pump that imports Mn2+ into the Golgi lumen. This cation is the cofactor of Golgi-resident mannosyltransferases, and thus Pmr1 is involved in the synthesis of both N- and O-linked mannans. Since we currently have limited information about the genetic network behind the Candida tropicalis protein mannosylation machinery, we disrupted OCH1 and PMR1 in this organism. The C. tropicalis pmr1Δ and och1Δ mutants showed increased doubling times, aberrant colony and cellular morphology, reduction in the wall mannan content, and increased susceptibility to wall perturbing agents. These changes were accompanied by increased exposure of both β1,3-glucan and chitin at the wall surface of both mutant strains. Our results showed that O-linked mannans are dispensable for cytokine production by human mononuclear cells, but N-linked mannans and β1,3-glucan are key ligands to trigger cytokine production in a co-stimulatory pathway involving dectin-1 and mannose receptor. Moreover, we found that the N-linked mannan core found on the surface of C. tropicalis och1Δ null mutant was capable of inducing cytokine production; and that a mannan-independent pathway for IL-10 production is present in the C. tropicalis-mononuclear cell interaction. Both mutant strains showed virulence attenuation in the Galleria mellonella and the mouse model of systemic candidiasis. Therefore, mannans are relevant for cell wall composition and organization, and for the C. tropicalis-host interaction. © Copyright © 2019 Hernández-Chávez, Clavijo-Giraldo, Novák, Lozoya-Pérez, Martínez-Álvarez, Salinas-Marín, Hernández, Martínez-Duncker, Gácser and Mora-Montes

PCR ESPÉCIE-ESPECÍFICO PARA O DIAGNÓSTICO DE ESPOROTRICOSE CAUSADA POR S. BRASILIENSIS

Despite thousands of sporotrichosis cases related to the zoonotic transmission of Sporothrix brasiliensis have been described, the diagnostic gold standard is still the classical culturing methods. The mycological culture results are available afterseven to 30 days of incubation. Since an early diagnosis contributes to improving thetreatment and to the spread control of this mycosis, studies evaluating faster diagnosticmethods are needed. Therefore, we aimed to evaluate the species-specific PCR for thesporotrichosis diagnosis caused by S. brasiliensis, using samples collected with a noninvasive technique. Seventy-four swabs from feline (n=64), canine (n=5), and human(n=5) suspect sporotrichosis cases were included. All samples were submitted to classicalmethods for diagnosis and to S. brasiliensis-specific PCR. Using mycological culture asthe gold standard, the diagnosis of S. brasiliensis-caused infection was confirmed in 69%(51/74) of the cases. PCR was positive in 30 out of these 51 cases, showing 59%sensitivity, 100% specificity, 72% accuracy, 100% positive predictive value, and 52%negative predictive value. Consequently, more studies are needed to elucidate theinterference factors that culminated with the high rate of false-negative results and thenoptimize this molecular test for the accurate diagnosis of infections caused by S.brasiliensis.Apesar de milhares de casos de esporotricose relacionados a transmissão zoonótica por Sporothrix brasiliensis venham sendo descritos, o diagnóstico padrão-ouro ainda é a partir do método clássico de cultura. O resultado da cultura micológica demora de sete a trinta dias para ficar disponível. Considerando que o diagnóstico precoce contribuiria para um tratamento prematuro e com isso, com o controle na disseminação desta micose, estudos avaliando um diagnóstico precoce são necessários. Portanto, o objetivo do presente estudo foi avaliar o PCR espécie-específico para o diagnóstico da esporotricose causada por S. brasiliensis, utilizando amostras coletas por uma técnica não invasiva. Foram incluídas setenta e quatro amostras de casos suspeitos de esporotricose (swabs) oriundos de felinos (n=64), caninos (n=5) e humanos (n=5). Todas as amostras foram submetidas ao método clássico de diagnóstico e ao PCR específico para S. brasiliensis. Utilizando a cultura micológica como padrão-ouro, o diagnóstico da infecção causada por S. brasiliensis foi confirmado em 69% (51/74) dos casos. O PCR foi positivo em 30 dos 51 casos, demonstrando 59% de sensibilidade, 100% de especificidade, 72% de acurácia, 100% de valor preditivo positivo e 52% de valor preditivo negativo. Consequentemente, mais estudos são necessários para elucidar os fatores de transferência que culminaram com a alta taxa de resultados falsos negativos e então otimizar este teste molecular para a acurácia diagnóstica para infecções causadas por S. brasiliensis

Generation of Sporothrix schenckii mutants expressing the green fluorescent protein suitable for the study of host-fungus interactions

"Sporotrichosis is an infection caused by members of the Sporothrix genus, and among them, Sporothrix schenckii is one of the etiological agents. Both, the disease and the causative agent have gained interest in the recent years, because of the report of epidemic outbreaks, and the description of the disease transmission from animals to human beings. Despite the relevance of S. schenckii in the clinical field, there are basic aspects of its biology poorly explored. So far, Agrobacterium tumefaciens-mediated transformation has been reported as an alternative for genetic manipulation of this fungal pathogen. Here, we report the optimization of the transformation method and used this to generate insertional mutants that express the green fluorescent protein in S. schenckii. We obtained five mutant strains that showed mitotic stability and expression of the reporter gene. The strains displayed normal cell wall composition, and a similar ability to interact ex vivo with human monocytes and monocyte-derived macrophages. Moreover, the virulence in larvae of Galleria mellonella was similar to that obtained with the wild-type control strains. These data indicate that these fluorescent mutants with normal ability to interact with the host could be used in bioimaging to track the host-Sporothrix interaction in vivo.

Patrimonio biocultural. Experiencias integradoras

El libro engloba diferentes perspectivas en torno al patrimonio biocultural de diferentes regiones de México, desde un contexto histórico, hasta las problemáticas político-administrativas a las que se enfrentan estás regiones. Algunos capítulos reflejan diferentes estrategias que han seguido las comunidades para rescatar ese patrimonio biocultural y avanzar hacia la sustentabilidad.El libro fue resultado del 1er Congreso Internacional Desarrollo Sustentable: Enfoques, Aplicaciones y Perspectivas. “Ambiente, Economía, Sociedad, Territorio y Educación”. Celebrado en Toluca, Estado de México.De forma particular, el cuerpo académico sobre sustentabilidad, territorio y educación, llevo a cabo una recopilación de investigaciones en diferentes líneas de trabajo entre ellas las referentes al patrimonio biocultural y la sustentabilidad. En los trabajos aceptados se tienen experiencias que integran un sin número de aspectos que relacionan al ambiente con el patrimonio.La estructura del documento se divide en ocho capítulos y en cada uno de desarrolla la experiencia integradora del investigador