ABSTRACT
Introduction: Fusarium is a very heterogeneous group of fungi, difficult to classify, with a wide range of living styles, acting as saprophytes, parasites of plants, or pathogens for humans and animals. Prevalence of clinical fusariosis and lack of effective treatments have increased the interest in the precise diagnosis, which implies a molecular characterization of Fusarium populations. Objective: We compared different genotyping markers in their assessment of the genetic variability and molecular identification of clinical isolates of Fusarium. Materials and methods: We evaluated the performance of the fingerprinting produced by two random primers: M13, which amplifies a minisatellite sequence, and (GACA)4, which corresponds to a simple repetitive DNA sequence. Using the Hunter Gaston Discriminatory Index (HGDI), an analysis of molecular variance (AMOVA), and a Mantel test, the resolution of these markers was compared to the reference sequencing-based and PCR genotyping methods. Results: The highest HGDI value was associated with the M13 marker followed by (GACA)4. AMOVA and the Mantel tests supported a strong correlation between the M13 classification and the reference method given by the partial sequencing of the transcription elongation factor 1-alpha (TEF1-α) and rDNA 28S. Conclusion: The strong correlation between the M13 classification and the sequencing-based reference together with its higher resolution demonstrates its adequacy for the characterization of Fusarium populations.
Introducción. Fusarium es un grupo heterogéneo de hongos, difícil de clasificar y con una amplia gama de estilos de vida, que actúa como saprófito, parásito de plantas o patógeno de humanos y animales. La prevalencia de la fusariosis clínica y la falta de tratamientos han incrementado el interés en su diagnóstico preciso, lo que conlleva la caracterización molecular de las poblaciones. Objetivo. Comparar marcadores de genotipificación en la evaluación de la variabilidad genética e identificación de aislamientos clínicos de Fusarium. Materiales y métodos. Se evaluó la huella genética producida por dos cebadores aleatorios: M13, que amplifica una secuencia minisatélite, y (GACA)4, que corresponde a una secuencia repetitiva de ADN. Utilizando el índice discriminatorio de Hunter Gaston (HGDI), el análisis de varianza molecular (AMOVA) y una prueba de Mantel, se comparó la resolución de estos marcadores con métodos de genotipificación basados en secuenciación y PCR. Resultados. El mayor HGDI se asoció con el marcador M13, seguido de (GACA)4. Las pruebas AMOVA y Mantel mostraron correlación entre las clasificaciones obtenidas con M13 y la referencia basada en la secuenciación parcial del factor de elongación de transcripción 1-alfa (TEF1-α) y el ADNr 28S. Conclusión. La fuerte correlación entre la clasificación obtenida con M13 y el método de referencia, así como su alta resolución, demuestran su idoneidad para la caracterización de poblaciones de Fusarium.
Subject(s)
Fusarium , DNA Fingerprinting , Bacteriophage M13 , Fusariosis , Genotyping Techniques , Elongin , Genetics, PopulationABSTRACT
Objective To construct active phages against Chlamydia trachomatis,and to evaluate its effect on Chlamydia trachomatis.Methods The M13 phage was recombined with the IN5 sequences encoding the capsid protein VP1 of chlamydiophage phiCPG1,and then the recombinant M13-IN5 phage was obtained.PCR amplification,enzyme digestion and sequencing were performed to verify whether the target fragment was inserted into the phage successfully.The viability of the phage was evaluated by plaque formation assay.Cell counting kit-8 (CCK8) assay was conducted to evaluate the effect of M13 phage and recombinant M13-IN5 phage at the titer of 1011 plaque-forming units (PFU)/ml on the proliferation of Hela cells,and Hela cells uninfected with chlamydia served as the blank control group.Western blot analysis was performed to determine the expression of the IN5 loop protein in the recombinant M13-IN5 phage,M13 phage and Escherichia coli ER2738 at exponential growth phase.Cultured standard Chlamydia trachomatis serovar E strain was treated with M13 phage and recombinant M13-IN5 phage at the titer of 1011 PFU/ml separately,and chlamydia control group without the treatment with phages was set up.After 36-hour infection,confocal microscopy was performed to detect the location of the M13 phage and the recombinant M13-IN5 phage.Moreover,iodine staining was conducted to count inclusion bodies at 36,48,60 and 72 hours separately after infection.Statistical analysis was carried out by a two-sample t-test for comparisons between two groups,one-way analysis of variance (ANOVA) for intergroup comparison,and Bonferroni test for multiple comparisons.Results The bioactive recombinant M13 phage containing the IN5 loop gene was constructed successfully,and Western blot analysis confirmed that the recombinant phage expressed IN5 loop/p Ⅲ fusion protein with a high titer of 3.05 × 1011 PFU/ml.As CCK8 assay showed,there was no significant difference in proliferation of Hela cells among the blank control group,M 13 phage group and recombinant M13-IN5 phage group (A450 values:3.63 ± 0.01,3.55 ± 0.02,3.70 ± 0.01,respectively,F =12.0,P ＞ 0.05).Confocal microscopy showed overlap between the phage fluorescence and chlamydial inclusion body fluorescence.The M13-IN5 phage group and M13 phage group both showed significantly decreased number of inclusion bodies compared with the control group (both P ＜ 0.05) at 36 and 72 hours after chlamydial infection,and the number of inclusion bodies was significantly lower in the M 13-IN5 phage group than in the M13 phage group (P ＞ 0.05).After 48,and 60 hours of chlamydial infection,the number of inclusion bodies did not differ among the M13 phage group,M13-IN5 phage group and control group (both P ＞ 0.05).Conclusions The recombinant M13-IN5 phage was bioactive and could successfully express the IN5 loop protein.In the in vitro experiments,the recombinant phage could enter into chlamydia inclusion bodies,and markedly inhibited the infection of Chlamydia trachomatis.
ABSTRACT
Objective To obtain the short peptides from phage-displayed random peptide library through screening the epitope of monoclonal antibody against tumor necrosis factor(TNF-?). Methods Anti-TNF-? was used to immunoscreen a phage random peptide library of 12 amino-acidresidues displayed as a fusion to protein Ⅲ of filamentous phage M13. The positive clones were obtained by three rounds of biopanning, and the reactivity of each clone binding to anti-TNF-? was examined by double-antibody sandwich ELISA and Dot-ELISA. Mixed positive phage clones were used to detect the serum from SLE patients and healthy persons by Dot-ELISA. Results The eluted phages were enriched nearly 100 fold through three rounds of biopanning, 7 phage clones from the third round biopanning were randomly selected and 5 clones of them could bind to the anti-TNF-?. The binding rate of mixed clones with SLE patients was significantly higher than that of healthy persons. Conclusion The phage display technique can be applied to study the anti-TNF-? antigenic peptides, and these epitopes provide the potential for developing immunodiagnostic reagents of vaccines.