RESUMEN
Lentinula edodes partitivirus 1 (LePV1), a new mycovirus possibly responsible for serious morphological deformities during L. edodes cultivation, is widespread in the Chinese L. edodes germplasm. Here, LePV1 isolates from the Chinese genetically-diverse L. edodes core collection were identified to be highly conserved and devoid of codivergence between virus and its hosts. Phylogenetic analysis showed that the LePV1 isolates could be grouped into two distinct clades (subtype I and subtype II), without geographical bias in the composition of this population. Compared with the other LePV1 isolates, one non-synonymous variation was observed in the LePV1 isolate from the symptomatic strain SX12. Purifying selection appears to be the main evolutionary force acting on LePV1 and it may be subject to negative selection. Based on the aforementioned results, the domestication history of L. edodes in China and the high frequency of virus incidence in basidiospores, we postulate that LePV1 may exist in nature and have had relationship with L. edodes wild strains since early times. Moreover, wind-blown spores carrying LePV1 may play an important role for the transmission of LePV1 in nature, while artificial activities such as vegetative propagation and hybridization breeding may also transmit virus from wild strains to cultivated ones.
Asunto(s)
Virus Fúngicos/clasificación , Virus Fúngicos/genética , Filogenia , Hongos Shiitake/virología , Secuencia de Bases , China , Variación Genética , Genoma Viral/genética , Sistemas de Lectura Abierta , ARN Viral/genética , Selección Genética , Análisis de Secuencia de ARN , Homología de Secuencia , Esporas/virologíaRESUMEN
Bacillus anthracis, the causative agent of anthrax, was utilized as a bioterrorism agent in 2001 when spores were distributed via the U.S. postal system. In responding to this event, the Federal Bureau of Investigation used traditional bacterial culture viability assays to ascertain the extent of contamination of the postal facilities within 24 to 48 h of environmental sample acquisition. Here, we describe a low-complexity, second-generation reporter phage assay for the rapid detection of viableB. anthracis spores in environmental samples. The assay uses an engineered B. anthracis reporter phage (Wß::luxAB-2) which transduces bioluminescence to infected cells. To facilitate low-level environmental detection and maximize the signal response, expression of luxABin an earlier version of the reporter phage (Wß::luxAB-1) was optimized. These alterations prolonged signal kinetics, increased light output, and improved assay sensitivity. Using Wß::luxAB-2, detection of B. anthracis spores was 1 CFU in 8 h from pure cultures and as low as 10 CFU/g in sterile soil but increased to 10(5)CFU/g in unprocessed soil due to an unstable signal and the presence of competing bacteria. Inclusion of semiselective medium, mediated by a phage-expressed antibiotic resistance gene, maintained signal stability and enabled the detection of 10(4)CFU/g in 6 h. The assay does not require spore extraction and relies on the phage infecting germinating cells directly in the soil sample. This reporter phage displays promise for the rapid detection of low levels of spores on clean surfaces and also in grossly contaminated environmental samples from complex matrices such as soils.
Asunto(s)
Fagos de Bacillus/crecimiento & desarrollo , Fagos de Bacillus/genética , Bacillus anthracis/aislamiento & purificación , Bacillus anthracis/virología , Técnicas Microbiológicas/métodos , Esporas/aislamiento & purificación , Esporas/virología , Microbiología Ambiental , Genes Reporteros , Luciferasas/análisis , Luciferasas/genética , Mediciones Luminiscentes , Sensibilidad y Especificidad , Factores de TiempoRESUMEN
Isolates (178) belonging to Aspergillus sections Fumigati, Candidi, Clavati, and Circumdati were tested for the presence of double-stranded RNA (dsRNA) genomes. Altogether, 5.6% of the Aspergillus strains examined were infected with dsRNAs. dsRNA segments indicative of mycovirus infection were observed for the first time in Neosartorya hiratsukae, Neosartorya quadricincta, Petromyces alliaceus, and Aspergillus clavatus strains. Correlation was not observed between ochratoxin production and dsRNA content of the strains. This is the first report on the detection of naturally occurring dsRNAs in Aspergillus species that are able to reproduce sexually. The detection of dsRNA in sexual aspergilli gave us a chance to examine the transmission of these segments through ascospores. A Neosartorya hiratsukae strain transmitted the dsRNAs efficiently through sexual spores, while the stromata embedding the asci in Petromyces alliaceus did not transmit one of the dsRNA segments. The 0.6-kb dsRNA segment that was present in the single-stromatal cultures was found to be located in the mitochondrial fraction of this strain. This observation indicates that some mechanisms exist in aspergilli to exclude cytoplasmically located dsRNA molecules from stromatal structures.