Lack of relationship between genotype and virulence in Candida species / Ausencia de relación entre el genotipo y la virulencia en especies de Candida

BACKGROUND: The virulence of isolates among different Candida species causing candidemia may play a role in the prognosis of the patients. Furthermore, the potential relationship between genotype and virulence is still unclear and need to be further studied. AIMS: We aim to assess the relationship between genotype and virulence in Candida species using a Galleria mellonella larvae infection model. METHODS: One hundred and ninety-four isolates from 68 clusters (Candida albicans, 114/41; Candida parapsilosis, 74/24; Candida tropicalis, 6/3) were compared against the same number of each species singleton genotypes in terms of survival of G. mellonella larvae. RESULTS: The median of survival and the IQR ranges of clusters and singleton were as follows: C. albicans (2 days, IQR 1.5-2 vs. 2 days, IQR 1-2.25), C. parapsilosis (2 days, IQR 1.5-2.6 vs. 2 days, IQR 2-3.3), and C. tropicalis (1 day, IQR 1-3.5 vs. 2 days, IQR 2-3.5; p < 0.05). High intra-cluster variability in terms of median of survival was found regardless the species. CONCLUSIONS: No relationship between genotype and virulence in Candida was observed with the G. mellonella model

ANTECEDENTES: La virulencia de cepas de diferentes especies de Candida causantes de candidemia puede jugar un papel en el pronóstico de los pacientes, y su estudio en el modelo de infección en Galleria mellonella puede ser útil para entender su contribución general a la infección. Además, la potencial relación entre genotipo y virulencia requiere de más estudios. OBJETIVOS: Se evaluó la relación entre genotipo y virulencia en especies de Candida mediante el modelo de infección de larvas de G. mellonella. MÉTODOS: Se estudió la supervivencia de las larvas infectadas con 194 aislados incluidos en 68 clusters (Candida albicans, 114/41; Candida parapsilosis, 74/24; Candida tropicalis, 6/3) y con el mismo número de aislados con genotipos únicos por especie. RESULTADOS: La mediana de supervivencia y los rangos intercuartílicos (IQR) de clusters y genotipos únicos se muestra a continuación: C. albicans (2 días, IQR: 1,5-2 vs. 2 días, IQR: 1-2,25), C. parapsilosis (2 días, IQR: 1,5-2,6 vs. 2 días, IQR: 2-3,3), y C. tropicalis (un día, IQR: 1-3,5 vs. 2 días, IQR: 2-3,5; p < 0,05). Encontramos una importante variabilidad en la mediana de supervivencia entre cepas del mismo cluster, independientemente de la especie analizada. CONCLUSIONES: No se encontró relación entre el genotipo y la virulencia entre los aislados de Candida evaluados mediante el modelo de infección de G. mellonella

Role of Candida species from HIV infected children in enamel caries lesions: an in vitro study.

OBJECTIVES: This study analyzed the capacity of Candida spp. from dental biofilm of HIV infected (HIV+) children to demineralize primary molar enamel in vitro by Transversal Microhardness (TMH), Polarized Light Microscopy (PLM) and the quantity of calcium ions (Ca2+) released from the enamel. MATERIAL AND METHODS: Candida spp. samples were isolated from the supragingival biofilm of HIV+ children. A hundred and forty (140) enamel blocks were randomly assigned to six groups: biofilm formed by C. albicans (Group 1); mixed biofilm formed by C. albicans and C. tropicalis (Group 2); mixed biofilm formed by C. albicans and C. parapsilosis (Group 3); mixed biofilm formed by C. albicans, C. parapsilosis and C. glabrata (Group 4); biofilm formed by C. albicans ATCC (Group 5) and medium without Candida (Group 6). Enamel blocks from each group were removed on days 3, 5, 8 and 15 after biofilm formation to evaluate the TMH and images of enamel were analyzed by PLM. The quantity of Ca2+ released, from Groups 1 and 6, was determined using an Atomic Absorption Spectrophotometer. The SPSS program was used for statistical analysis and the significance level was 5%. RESULTS: TMH showed a gradual reduction in enamel hardness (p<0.05) from the 1st to 15th day, but mainly five days after biofilm formation in all groups. The PLM showed superficial lesions indicating an increase in porosity. C. albicans caused the release of Ca2+ into suspension during biofilm formation. CONCLUSION: Candida species from dental biofilm of HIV+ children can cause demineralization of primary enamel in vitro.

Role of Candida species from HIV infected children in enamel caries lesions: an in vitro study

Abstract Objectives This study analyzed the capacity of Candida spp. from dental biofilm of HIV infected (HIV+) children to demineralize primary molar enamel in vitro by Transversal Microhardness (TMH), Polarized Light Microscopy (PLM) and the quantity of calcium ions (Ca2+) released from the enamel. Material and Methods Candida spp. samples were isolated from the supragingival biofilm of HIV+ children. A hundred and forty (140) enamel blocks were randomly assigned to six groups: biofilm formed by C. albicans (Group 1); mixed biofilm formed by C. albicans and C. tropicalis (Group 2); mixed biofilm formed by C. albicans and C. parapsilosis (Group 3); mixed biofilm formed by C. albicans, C. parapsilosis and C. glabrata (Group 4); biofilm formed by C. albicans ATCC (Group 5) and medium without Candida (Group 6). Enamel blocks from each group were removed on days 3, 5, 8 and 15 after biofilm formation to evaluate the TMH and images of enamel were analyzed by PLM. The quantity of Ca2+ released, from Groups 1 and 6, was determined using an Atomic Absorption Spectrophotometer. The SPSS program was used for statistical analysis and the significance level was 5%. Results TMH showed a gradual reduction in enamel hardness (p<0.05) from the 1st to 15th day, but mainly five days after biofilm formation in all groups. The PLM showed superficial lesions indicating an increase in porosity. C. albicans caused the release of Ca2+ into suspension during biofilm formation. Conclusion Candida species from dental biofilm of HIV+ children can cause demineralization of primary enamel in vitro.

The evolution of novel fungal genes from non-retroviral RNA viruses.

BACKGROUND: Endogenous derivatives of non-retroviral RNA viruses are thought to be absent or rare in eukaryotic genomes because integration of RNA viruses in host genomes is impossible without reverse transcription. However, such derivatives have been proposed for animals, plants and fungi, often based on surrogate bioinformatic evidence. At present, there is little known of the evolution and function of integrated non-retroviral RNA virus genes. Here, we provide direct evidence of integration by sequencing across host-virus gene boundaries and carry out phylogenetic analyses of fungal hosts and totivirids (dsRNA viruses of fungi and protozoans). Further, we examine functionality by tests of neutral evolution, comparison of residues that are necessary for viral capsid functioning and assays for transcripts, dsRNA and viral particles. RESULTS: Sequencing evidence from gene boundaries was consistent with integration. We detected previously unknown integrated Totivirus-like sequences in three fungi (Candida parapsilosis, Penicillium marneffei and Uromyces appendiculatus). The phylogenetic evidence strongly indicated that the direction of transfer was from Totivirus to fungus. However, there was evidence of transfer of Totivirus-like sequences among fungi. Tests of selection indicated that integrated genes are maintained by purifying selection. Transcripts were apparent for some gene copies, but, in most cases, the endogenous sequences lacked the residues necessary for normal viral functioning. CONCLUSIONS: Our findings reveal that horizontal gene transfer can result in novel gene formation in eukaryotes despite miniaturized genomic targets and a need for co-option of reverse transcriptase.