ABSTRACT
Las infecciones micóticas invasivas (IMI) constituyen una importante causa de morbimortalidad, en especial en los pacientes con factores de riesgo subyacentes (neutropenia, quimioterapia, trasplante, sida). Las especies de los géneros Candida y Aspergillus representan aun las causas relevantes de IMI, pero otros organismos están adquiriendo importancia creciente. Han surgido especies del género Aspergillus menos sensibles a los antifúngicos y se ha encontrado resistencia a los azólicos, especialmente en Aspergillus fumigatus. Asimismo, las infecciones debidas a especies de los géneros Trichosporon, Fusarium y Glomeromycota (antes llamado Zygomycetes) se han incrementado y se asocian con altas tasas de mortalidad. Algunas de estas infecciones emergentes se presentan como brotes durante el tratamiento con nuevos antifúngicos, como las equinocandinas o los azólicos. La incidencia, gravedad y pronóstico de las IMI dependen de manera acentuada del organismo causal, el estado del paciente, el nivel de inmunosupresión y la localización geográfica. El diagnóstico precoz y el reconocimiento de estos cambios epidemiológicos son críticos para la atención de los pacientes.
Subject(s)
Aspergillus , Candida/classification , Infection Control , Epidemiology , Mitosporic Fungi/classification , Mitosporic Fungi/metabolism , Mitosporic Fungi/virologyABSTRACT
Metarhizium anisopliae is the best-characterized entomopathogen and is used to control insect pests in sugar cane plantations in Brazil on a commercial scale. We have previously reported the infection of some M. anisopliae strains by dsRNA mycoviruses. Here we describe the purification and characterization of the viruses (MaV-A1, MaV-M5, MaV-RJ) in terms of dsRNA content, capsid proteins, electron microscopy, Western blot, and hybridization patterns. One spontaneous mutant lost some of the high molecular weight dsRNA components and showed significant alterations in colony morphology and spore production, suggesting that viral genes interfere with fungal phenotype. A comparison between dsRNA mycovirus-free and infected M. anisopliae isolates showed that virus-free isolates have increased endochitinase secretion. By comparing the following parameters: the buoyant density in CsCl of the presumed virions; the number and estimated molecular weight of the dsRNA components and the molecular mass of the capsid proteins to other mycoviruses previously described, we suggest the inclusion of MaV-A1 and MaV-M5 in the family Totiviridae and MaV-RJ in the family Partitiviridae.
Subject(s)
Capsid Proteins/metabolism , Chitinases/metabolism , Mitosporic Fungi/enzymology , Mitosporic Fungi/virology , RNA Viruses/growth & development , Antibodies, Viral/blood , Blotting, Western , Brazil , Capsid Proteins/isolation & purification , Microscopy, Electron , Nucleic Acid Hybridization , Pest Control, Biological , RNA Viruses/genetics , RNA Viruses/metabolism , RNA, Viral/chemistry , RNA, Viral/genetics , Reverse Transcriptase Polymerase Chain ReactionABSTRACT
DsRNA viruses were transferred from a virus-containing strain to a virus-free strain of Phaffia rhodozyma by protoplast fusion. The resulting new strain carried all three types of dsRNA of the virus-containing strain and had the electrophoretic karyotype of the virus-free strain. The effects of the dsRNA viruses on the host fitness were checked by following the asexual and the sexual reproductivity. The results demonstrated that viruses have no effect on the growth rate during the lag and log phases of the vegetative reproduction, but the maximum cell numbers in the stationary phase differ significantly. Inconclusive results were obtained as concerns the effects of viruses on the sexual reproduction.
Subject(s)
Basidiomycota/virology , Mitosporic Fungi/virology , RNA Viruses/isolation & purification , RNA, Double-Stranded , Yeasts/virology , Basidiomycota/growth & development , Mitosporic Fungi/genetics , Yeasts/growth & developmentABSTRACT
Unsegmented double-stranded (ds)RNA viruses belonging to the family Totiviridae persistently infect protozoa and fungi. In this study, two totiviruses were found to coinfect the filamentous fungus Sphaeropsis sapinea, a well known pathogen of pines. Isometric, virus-like particles approximately 35 nm in diameter were isolated from extracts of this fungus. The nucleotide sequences of the genomes of the two S. sapinea RNA viruses named SsRV1 and SsRV2 were established. The linear genomes of 5163 and 5202 bp, respectively, are identically organized with two large, overlapping ORFs. The 5' located ORF1 probably encodes the coat protein, whereas the gene product of ORF2 shows the typical features of RNA-dependent RNA polymerases. The absence of a pseudoknot and a slippery site at the overlapping region between ORF1 and ORF2, as well as the shortness of that region, leads us to suggest that the translation of ORF2 of both viruses is internally initiated. The mode of translation and the genomic organization are similar to those of Helminthosporium victoriae 190S virus (Hv190SV; Huang, S., and Ghabrial, S. A. (1996). Proc. Natl. Acad. Sci. USA 93, 12541-12546). Hv190SV thus appears to be closely related to the SsRVs. Interestingly, based on amino acid sequence homology SsRV1 is more closely related to Hv190SV than to SsRV2.
Subject(s)
Capsid/genetics , Genome, Viral , Mitosporic Fungi/virology , Phylogeny , RNA, Double-Stranded/genetics , Totiviridae/genetics , Amino Acid Sequence , Base Sequence , Capsid/chemistry , Evolution, Molecular , Molecular Sequence Data , Open Reading Frames , Sequence Alignment , Sequence Homology, Amino Acid , Sequence Homology, Nucleic Acid , Totiviridae/classification , Totiviridae/ultrastructure , Trees/microbiologyABSTRACT
In wild-type Botrytis cinerea CVg25 strain we have detected the presence of extrachromosomal genetic elements corresponding to double-stranded RNA molecules. These genetic elements have been designated L, M1 and M2 with molecular sizes of 8.3, 2.0 and 1.4 kb, respectively. The visualization by electron microscopy of mycelium ultrathin sections from B. cinerea CVg25 showed the presence of isometric virus-like particles of about 40 nm in diameter. Linear sucrose gradient centrifugation of mycelium-free extracts was done to determine if the double-stranded RNAs were associated with virus-like particles. The gradient profile obtained at 260 and 280 nm revealed a major peak that was analyzed by both agarose-gel electrophoresis and electron microscopy. It was observed that only the L-double-stranded RNA molecule copurified with isometric virus-like particles. These virus-like particles had a similar morphology and size as those detected by electron microscopy in the mycelium sections. These results suggest that only the L-double-stranded RNA would be encapsidated.
Subject(s)
Mitosporic Fungi/virology , RNA Viruses/ultrastructure , Extrachromosomal Inheritance , Genome, Viral , Inclusion Bodies, Viral/ultrastructure , Microscopy, Electron , RNA Viruses/genetics , RNA Viruses/isolation & purification , RNA, Double-Stranded/genetics , RNA, Double-Stranded/isolation & purification , RNA, Viral/genetics , RNA, Viral/isolation & purificationABSTRACT
The relationship involving the presence of sterile hyphae in moulds and their inhibitory activity on 34 micro-organisms was investigated. From the results it was evident that antimicrobial activity varied when morphological changes were observed in the cultures.
Subject(s)
Antibiosis , Mitosporic Fungi/virology , Anti-Bacterial Agents/biosynthesis , Bacterial Physiological Phenomena , Microscopy, Electron , Mitosporic Fungi/cytology , Mitosporic Fungi/physiologyABSTRACT
Four double-stranded RNA (dsRNA) molecules were isolated from Phaffia rhodozyma UCD 67-385. Their molecular sizes were approximately 4.3, 3.1, 0.9 and 0.75 kilobase pairs (kbp) as determined by agarose-gel electrophoresis and they were designated as L, M, S1 and S2, respectively. By differential centrifugation in sucrose gradients, these dsRNAs copurified with isometric virus-like particles 36 nm in diameter. A cured strain, UV-S2, lacking the S2-dsRNA was obtained from P. rhodozyma UCD 67-385 by ultraviolet (UV) light treatment. UV-S2 strain contains identical virus-like particles to those from the wild-type strain, as determined by electron microscopy, suggesting that the S2-dsRNA was not essential for the expression of mycovirus structural polypeptides. On the other hand, both the UCD 67-385 and UV-S2 strains were able to kill P. rhodozyma UCD 67-383, a strain without dsRNAs. These results suggest that the dsRNA molecules also encode a killer system. Finally, the UV-S2 strain maintains killer ability, which suggests that S2-dsRNA is not involved in the killer phenotype expression.
Subject(s)
Extrachromosomal Inheritance , Inclusion Bodies, Viral/ultrastructure , Mitosporic Fungi/genetics , Mitosporic Fungi/virology , RNA, Double-Stranded/genetics , RNA, Double-Stranded/isolation & purification , RNA, Fungal/genetics , RNA, Fungal/isolation & purification , Killer Factors, Yeast , Microscopy, Electron , Mitosporic Fungi/ultrastructure , Molecular Weight , Mycotoxins/genetics , PhenotypeABSTRACT
El presente trabajo ha sido realizado con el objeto de evaluar el efecto potencial patogénico de conidios y blastosporas de Aphanocladium album y Tolypocladium cylindrosporum contra larvas de Culex pipiens L. Un alto porcentaje de mortalidad larval se observó frente a las dos especies fúngicas, siendo para A.album, 85,6 porciento y para T.cylindrosporum 80 porciento, con dosis de 1x10,6 conidios/ml. En A.album la actividad de blastosporos y conidios fué similar, mientras que para T.cylindrosporum fueron más virulentos los conidios que las blastosporas. De los resultados obtenidos se deduce que ambas especies fúngicas tienen una elevada virulencia contra larvas de C.pipiens y sus potencialidades patogénicas justifican nuevos estudios sobre este tema
