1,721,018 research outputs found
Porcine circovirus 3 (PCV-3) as a causal agent of disease in swine and a proposal of PCV-3 associated disease case definition
Full text linkPorcine circovirus 3 (PCV-3) was discovered in 2015 using next-generation sequencing (NGS) methods. Since then, the virus has been detected worldwide in pigs displaying several clinical–pathological outcomes as well as in healthy animals. The objective of this review is to critically discuss the evidence existing so far regarding PCV-3 as a swine pathogen. In fact, a significant number of publications claim PCV-3 as a disease causal infectious agent, but very few of them have shown strong evidence of such potential causality. The most convincing proofs of disease association are those that demonstrate a clinical picture linked to multisystemic lymphoplasmacytic to lymphohistiocytic perivascular inflammation and presence of viral nucleic acid within these lesions. Based on these evidence, individual case definitions for PCV-3-reproductive disease and PCV-3-systemic disease are proposed to standardize diagnostic criteria for PCV-3-associated diseases. However, the real frequency of these clinical–pathological conditions linked to the novel virus is unknown, and the most frequent outcome of PCV-3 infection is likely subclinical based on its worlwide distribution
Porcine circovirus 2 genotypes, immunity and vaccines: Multiple genotypes but one single serotype
Full text linkIdentified for the first time in the 1990s, Porcine circovirus 2 (PCV-2) should not be considered an emerging virus anymore. Nevertheless, many aspects of its biology and epidemiology are still controversial. Particularly, its high evolutionary rate has caused the emergence of several variants and genotypes, alternating on the worldwide proscenium. The biological and practical implications of such heterogenicity are unfortunately largely unknown. The effectiveness of currently available vaccines against new genotypes that have emerged over time has been the topic of an intense debate and often inconclusive or contradictory results between experimental, field, and epidemiological studies have been gathered. The challenge in establishing an effective PCV-2 disease model, the peculiarities in experimental design and settings and the strains involved could justify the observed differences. The present work aims to summarize and critically review the available knowledge on PCV-2 genetic heterogeneity, immunity, and vaccine efficacy, organizing and harmonizing the available data from different sources, shedding light on this complex field and highlighting current knowledge gaps and future perspectives. So far, all vaccines in the market have shown great efficacy in reducing clinical signs associated to diseases caused by PCV-2, independently of the genotype present in the farm. Moreover, experimental data demonstrated the cross-protection of PCV-2a vaccines against the most widespread genotypes (PCV-2a, PCV-2b, and PCV-2d). Therefore, despite the significant number of genotypes described/proposed (PCV-2a to PCV-2i), it seems one single PCV-2 serotype would exist so far
Lack of porcine circovirus 4 genome detection in pig samples from Italy and Spain
Full text linkThe genus Circovirus includes several species and mostly causes asymptomatic infections. Porcine circovirus 2 (PCV-2) and, with increasing evidence, Porcine circovirus 3 (PCV-3), have been associated with different clinical conditions all over the world. In 2019, a new porcine circovirus (PCV-4) was identified from diseased animals in China. Because of the lessons learned from PCV-2 and PCV-3, it appears mandatory to investigate the actual distribution of this new virus and its potential association with clinical outcomes. To this purpose, an exploratory study to detect PCV-4 by molecular methods was performed in Italy and Spain by testing more than 300 samples of different types (serum and tissues), collected from both healthy and diseased pigs and wild boar as well. All samples, independently from the country, type, health status and host, tested PCV-4 negative. Therefore, no evidence of PCV-4 presence was found in Italy and Spain through this exploratory study. Considering the dense pig trade among European countries, its presence in the continent can similarly be considered unlikely. The reasons behind the restricted PCV-4 distribution compared to other porcine circoviruses will require further investigations. Careful surveillance might nevertheless be important since prompt recognition of PCV-4 would allow the implementation of effective countermeasures to prevent its spreading and potential economic losses
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
Porcine circovirus 2 (PCV2) population study in experimentally infected pigs developing PCV2-systemic disease or a subclinical infection
Full text linkPorcine circovirus 2 (PCV2) is a single stranded DNA virus with one of the highest mutation rates among DNA viruses. This ability allows it to generate a cloud of mutants constantly providing new opportunities to adapt and evade the immune system. This pig pathogen is associated to many diseases, globally called porcine circovirus diseases (PCVD) and has been a threat to pig industry since its discovery in the early 90’s. Although 11 ORFs have been predicted from its genome, only two main proteins have been deeply characterized, i.e. Rep and Cap. The structural Cap protein possesses the majority of the epitopic determinants of this non-enveloped virus. The evolution of PCV2 is affected by both natural and vaccine-induced immune responses, which enhances the genetic variability, especially in the most immunogenic Cap region. Intra-host variability has been also demonstrated in infected animals where long-lasting infections can take place. However, the association between this intra-host variability and pathogenesis has never been studied for this virus. Here, the within-host PCV2 variability was monitored over time by next generation sequencing during an experimental infection, demonstrating the presence of large heterogeneity. Remarkably, the level of quasispecies diversity, affecting particularly the Cap coding region, was statistically different depending on viremia levels and clinical signs detected after infection. Moreover, we proved the existence of hyper mutant subjects harboring a remarkably higher number of genetic variants. Altogether, these results suggest an interaction between genetic diversity, host immune system and disease severity
Genotyping of porcine circovirus 2 (Pcv-2) in vaccinated pigs suffering from pcv-2-systemic disease between 2009 and 2020 in spain
Full text linkVaccination against porcine circovirus 2 (PCV-2) is a common practice all over the world. Vaccines can prevent PCV-2-systemic disease (PCV-2-SD) outbreaks but not PCV-2 infection, which can be detectable in a percentage of vaccinated animals. Occasionally, PCV-2-SD is diagnosed in vaccinated farms. The objective of this study was to genotype the PCV-2 strains detected in vaccinated animals diagnosed with PCV-2-SD. Additionally, the evolution of the frequency of PCV-2 genotype detection at Spanish, European, and world levels was assessed. Fifty cases diagnosed as PCV-2-SD between 2009 and 2020 were included in this study. PCV-2 genotype was determined by sequencing the Cap gene region. Among them, only PCV-2b (23/50, 46%) and PCV-2d (27/50, 54%) genotypes were detected. Although the frequency of detection of these two genotypes was similar, their temporal distribution was different. Whereas most PCV-2b sequences (17/23, 74%) were detected between 2009 and 2012, PCV-2d sequences were obtained from 2013 to 2020. Indeed, a predominance of the PCV-2d genotype was observed from 2013 onwards, a trend also noticed at European and world levels. The results suggest that detection of particular genotypes in vaccinated animals probably reflects the general prevalence of the genotypes over time rather than genotype-specific vaccine-immunity escaping
Comprehensive Analysis of Codon Usage Patterns in Chinese Porcine Circoviruses Based on Their Major Protein-Coding Sequences
Full text linkPorcine circoviruses (PCVs) are distributed in swine herds worldwide and represent a threat to the health of domestic pigs and the profits of the swine industry. Currently, four PCV species, including PCV-1, PCV-2, PCV-3 and PCV-4, have been identified in China. Considering the ubiquitous characteristic of PCVs, the new emerged PCV-4 and the large scale of swine breeding in China, an overall analysis on codon usage bias for Chinese PCV sequences was performed by using the major proteins coding sequences (ORF1 and ORF2) to better understand the relationship of these viruses with their host. The data from genome nucleotide frequency composition and relative synonymous codon usage (RSCU) analysis revealed an overrepresentation of AT pair and the existence of a certain codon usage bias in all PCVs. However, the values of an effective number of codons (ENC) revealed that the bias was of low magnitude. Principal component analysis, ENC-plot, parity rule two analysis and correlation analysis suggested that natural selection and mutation pressure were both involved in the shaping of the codon usage patterns of PCVs. However, a neutrality plot revealed a stronger effect of natural selection than mutation pressure on codon usage patterns. Good host adaptation was also shown by the codon adaptation index analysis for all these viruses. Interestingly, obtained data suggest that PCV-4 might be more adapted to its host compared to other PCVs. The present study obtained insights into the codon usage pattern of PCVs based on ORF1 and ORF2, which further helps the understanding the molecular evolution of these swine viruses
Diagnostic accuracy of two DNA-based molecular assays for detection of porcine circovirus 3 in swine population using Bayesian latent class analysis
No full textVariations on the Author
Full text link“Variations on the Author” discusses two of Eduardo Coutinho’s recent films (Um Dia na Vida, from 2010, and Últimas Conversas, posthumously released in 2015) and their contribution to the general question of documentary authorship. The director’s filmography is characterized by a consistent yet self-effacing form of authorial self-inscription: Coutinho often features as an interviewer that rather than express opinions propels discourses; an interviewer that is good at listening. This mode of self-inscription characterizes him as an author who is not expressive but who is nonetheless markedly present on the screen. In Um Dia na Vida, however, Coutinho is completely absent form the image, while Últimas Conversas, on the contrary, includes a confessional prologue that moves the director from the margins to the center of his films. This article examines the ways in which these works stand out in the filmography of a director who offers new insights into the notion of cinematic authorship
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