1,721,142 research outputs found
Disentangling the role of wild birds in avian metapneumovirus (aMPV) epidemiology: A systematic review and meta-analysis
Full text linkGiven the avian metapneumovirus (aMPV) disease burden in poultry worldwide and the evidence of a possible role played by wild birds in the virus epidemiology, the present study summarizes aMPV serological and molecular data on free-ranging avifauna available in the literature by conducting a systematic review and meta-analysis. A computerized literature research was performed on PubMed, Scopus, CAB Direct and Web of Science to identify relevant publications across the period 1990–2021, along with the screening of reference lists. A random-effect model was applied to calculate pooled prevalence estimates with 95% confidence intervals. The inconsistency index statistic (I2) was applied to assess between-study heterogeneity. Subgroup analyses for molecular studies only were performed according to geographical area of samplings, taxonomic order, genus and migration patterns of the birds surveyed. A total of 11 publications on molecular surveys and 6 on serological ones were retained for analysis. The pooled molecular prevalence was 6% (95% CI: 1–13%) and a high between-study heterogeneity was detected (I2 = 96%, p <.01). Moderator analyses showed statistically significant differences according to geographical area studied, taxonomic order and genus. Concerning serological prevalence, a pooled estimate of 14% (95% CI: 1–39%), along with a high between-study heterogeneity, was obtained (I2 = 98%, p <.01). Moderator analysis was not performed due to the scarcity of eligible serological studies included. Overall, molecular and serological evidence suggests that some wild bird taxa could play a role in aMPV epidemiology. Particularly, wild ducks, geese, gulls and pheasants, according to scientific contributions hereby considered, proved to be susceptible to aMPV, and due to host ecology, may act as a viral carrier or reservoir. Further surveys of wild birds are encouraged for a better comprehension of the poultry/wild bird interface in aMPV epidemiology and for better characterizing the virus host breadth
In vitro antiviral activity of Chestnut (Castanea spp.), Quebracho (Schinopsis spp.) and Tara (Caesalpinia spinosa) extracts against Avian Reovirus and Metapneumovirus
No full textSviluppi di un clone infettante di Metapneumovirus aviare codificante la proteina GFP (Green Fluorescent Protein)
No full textMetapneumovirus aviare (AMPV) è causa nel tacchino di una delle principali patologie di questa specie nota come Rinotracheite del Tacchino (TRT). Per la profilassi della TRT sono disponibili in commercio da oltre 15 anni vaccini vivi attenuati con metodi tradizionali, che hanno portato ad un netto miglioramento del controllo della malattia. Tuttavia ancora rimangono dubbi sulle performance di tali vaccini specie in condizioni di campo. Si è osservata ad esempio la tendenza a riacquisire patogenicità e tale fenomeno sembra essere la diretta conseguenza di mutazioni genetiche anche minime. Recentemente è stato messo a punto un sistema di reverse genetics per AMPV sottotipo A, che permette di introdurre in punti specifici del genoma mutazioni o delezioni, di ottenere cloni infettanti con i cambiamenti apportati e di valutarne le conseguenze fenotipiche. Tale sistema fornisce uno strumento fondamentale per indagare le basi molecolari della patogenicità, e più in generale per studiare la biologia del virus. Questo lavoro descrive l’utilizzo del sistema di reverse genetics per generare un AMPV-A ricombinante che esprima la proteina fluorescente GFP (Green Fluorescent Protein). In cDNA circolarizzato derivato da AMPV-A è stato inserito un sito di restizione mediante mutagenesi sito-specifica. Dopo taglio enzimatico è stato inserito in tale plasmide il gene che codifica per GFP. L’avvenuta ligazione, dopo trasformazione batterica, è stata verificata mediante screening delle singole colonie con specifiche PCR e successivo sequenziamento. Copie del plasmide purificato sono state trasfettate in cellule VERO con l’aggiunta di plasmidi di supporto che codificano per il complesso delle proteine ribonucleari (RNP). L’espressione della GFP è stata confermata mediante osservazione di fluorescenza al microscopio UV. Inoltre i risultati ottenuti mostrano come AMPV-A può essere manipolato geneticamente, grazie al sistema di reverse genetics, per esprimere stabilmente proteine estranee, mostrando un grosso potenziale di utilizzo quale vaccino vettore di proteine virali appartenenti a virus patogeni per i volatili o i mammiferi. Inoltre la disponibilità di AMPV-A esprimente la proteina fluorescente GFP potrà essere utile per studi di tropismo e patogenesi
Construction of GFP Avian Metapneumovirus (AMPV) recombinant lacking the small hydrophobic protein gene
No full textAn AMPV reverse-genetics system was used to create a virus lacking the entire SH
open reading frame which produced unusual giant syncytial formations in cell culture.
The replacement of the gene with GFP resulted in virus which also produced the
same syncytial formations. The intrinsic fluorescent properties of the virus may prove
useful in pathogenesis studies. The similarity of size of the 2 genes suggests that the
altered cytopathic effect did not result from the shortening of the genome and
possible consequential effects on the transcription or translation of the following
attachment and polymerase protein genes
Construction of a green fluorescent protein (GFP) Avian Metapneumovirus (AMPV) recombinant lacking the small hydrophobic (SH) protein gene shows that giant syncytial formations are not a result of the reduction in genome size
No full textAn AMPV reverse-genetics system was used to create a virus lacking the entire SH open reading frame which produced unusual giant syncytial formation in cell culture. The replacement of the gene with GFP resulted in virus which also produced the same syncytial formation. The intrinsic fluorescent properties of the virus may prove useful in pathogenesis studies. The similarity of size of the 2 genes suggests that the altered cytopathic effect did not result from the shortening of the genome and possible consequential effects on the transcription or translation of the following attachment and polymerase protein genes
Infectious bursal disease virus in free-living wild birds: A systematic review and meta-analysis of its sero-viroprevalence on a global scale
Full text linkInfectious bursal disease virus (IBDV) is an economically important pathogen for poultry, whereas knowledge of its occurrence in non-poultry hosts is limited. The objective of this systematic review and meta-analysis is to summarize the up-to-date knowledge about the sero-viroprevalence of IBDV in wild birds on a global scale. A computerized literature research was performed on PubMed, Scopus, CAB Direct and Web of Science to find relevant publications, along with the screening of reference lists. Journal articles, book chapters, scientific correspondences, conference proceedings and short communications on IBDV virological and/or serological surveys in free-living wild birds published between 1970 and 2021 were considered as eligible. Among 184 studies found, 36 original contributions met the pre-established criteria. A random-effect model was applied to calculate pooled seroprevalence estimates with 95% confidence intervals, whereas the paucity of virological studies (n = 6) only allowed a qualitative description of the data. The pooled seroprevalence was estimated to be 6% (95% CI: 3%–9%) and a high heterogeneity was detected (I2= 96%). Sub-group analyses were not performed due to the scarcity of available information about hypothetical moderators. With respect to virological studies, IBDV was detected in Anseriformes, Columbiformes, Galliformes, Passeriformes and Pelecaniformes and different strains related to poultry infection were isolated. Our estimates of serological data showed a moderate exposure of wild birds to IBDV. The susceptibility of different species to IBDV infection underlines their potential role in its epidemiology at least as carriers or spreaders. Indeed, the isolation of IBDV in healthy wild birds with a migratory attitude might contribute to a long-distance spread of the virus and to strain diversity. While a wild reservoir host could not be clearly identified, we believe our work provides useful insights for conducting future surveys which are needed to broaden our knowledge of IBDV occurrence in wild birds
Going Beyond Counting First Authors in Author Co-citation Analysis
Full text linkThe present study examines one of the fundamental aspects of author co-citation analysis (ACA) - the way co-citation
counts are defined. Co-citation counting provides the data on which all subsequent statistical analyses and mappings
are based, and we compare ACA results based on two different types of co-citation counting - the traditional type that
only counts the first one among a cited work's authors on the one hand and a non-traditional type that takes into
account the first 5 authors of a cited work on the other hand. Results indicate that the picture produced through this non-traditional author co-citation counting contains more coherent author groups and is therefore considerably clearer. However, this picture represents fewer specialties in the research field being studied than that produced through the traditional first-author co-citation counting when the same number of top-ranked authors is selected and analyzed. Reasons for these effects are discussed
- …
