91 research outputs found
Vaccine or field strains: the jigsaw pattern of infectious bronchitis virus molecular epidemiology in Poland
Infectious bronchitis (IB), caused by infectious bronchitis virus (IBV), account for severe economic losses in the poultry industry. The continuous emergence of a multitude of IBV variants poses many challenges for its diagnosis and control, and live attenuated vaccines, despite their routine use, still plays a significant role in driving IBV evolution, further complicating the epidemiological scenario. Unfortunately, the impact of different vaccination strategies on IB control, epidemiology, and diagnosis has rarely been investigated. This work presents the results of a large-scale diagnostic survey performed in Poland to study IBV molecular epidemiology and how vaccination may affect the viral circulation in the field. To this purpose, 589 samples were collected between May 2017 and January 2019, tested by reverse transcription-PCR for IBV and sequenced. Vaccine and field strains were discriminated based on genetic and anamnestic information. The most commonly detected lineages were 793B (79%) and variant 2 (17.4%), with sporadic detections of QX, Mass, and D274-like strains. Most of the detected strains had a vaccine origin: 46.3% matched one of the applied vaccines, while 36.5% were genetically related to vaccines not implemented in the respective protocol. Besides their practical value for the proper planning of vaccination protocols in Poland, these results suggest that only a fraction (17.2%) of the circulating strains are field ones, imposing a careful assessment of the actual IBV field menaces. Moreover, phenomena like vaccine spreading and persistence seem to occur commonly, stressing the need to further study the epidemiological consequences of the extensive use of live vaccines
Diagnostic accuracy of two DNAâbased molecular assays for detection of porcine circovirus 3 in swine population using Bayesian latent class analysis
Molecularâbased tools sometimes are the only laboratory techniques available to detect a recently discovered agent, and their validation without the existence of previously described âgold standardâ methods poses a challenge for the diagnosticians. A good example within this scenario is the recently described porcine circovirus 3 (PCVâ3) in the swine population worldwide, from which only few PCR methods have been described. Therefore, the primary objective of this study was to estimate the diagnostic accuracy of a direct PCR (dPCR) and a realâtime qPCR (qPCR) for detection of PCVâ3 in Italian swine population. Bayesian latent class analysis approach was used to rigorously assess their features and applicability in routine diagnostic activity. Data on dPCR and qPCR were available from 116 domestic pigs, which were randomly selected from 55 farms located at different regions in Northern Italy. The sensitivity (Se) estimates of dPCR (94%; posterior credible interval (PCI%) 84â100) and qPCR (96%; PCI% 90â100) were high and similar. The estimated specificity (Sp) of both dPCR and qPCR assays was around 97%. dPCR and qPCR assays showed a high and comparable Se and Sp estimates for the detection of PCVâ3 in Italian swine population.info:eu-repo/semantics/acceptedVersio
Canine parvovirus (CPV) phylogeny is associated with disease severity
After its first identification in 1978, canine parvovirus (CPV) has been recognized all around the world as a major threat for canine population health. This ssDNA virus is characterized by a high substitution rate and several genetic and phenotypic variants emerged over time. Overall, the definition of 3 main antigenic variants was established based on specific amino acid markers located in a precise capsid position. However, the detection of several minor variants and incongruence observed between the antigenic classification and phylogeny have posed doubts on the reliability of this scheme. At the same time, CPV heterogeneity has favored the hypothesis of a differential virulence among variants, although no robust and consistent demonstration has been provided yet. The present study rejects the antigenic variant concept and attempts to evaluate the association between CPV strain phylogeny, reconstructed using the whole information contained in the VP2 coding gene, and several clinical and hemato-biochemical parameters, assessed from 34 CPV infected dogs at admission. By using different statistical approaches, the results of the present study show an association between viral phylogeny and host parameters ascribable to immune system, coagulation profile, acute phase response and, more generally, to the overall picture of the animal response. Particularly, a strong and significant phylogenetic signal was proven for neutrophil count and WBC. Therefore, despite the limited sample size, a relation between viral phylogeny and disease severity has been observed for the first time, suggesting that CPV virulence is an inherited trait. The likely existence of clades with different virulence highlights once more the relevance of intensive epidemiological monitoring and research on CPV evolution to better understand the virulence determinants, their epidemiology and develop adequate countermeasures
Vaccine Interaction and Protection against Virulent Avian Metapneumovirus (aMPV) Challenge after Combined Administration of Newcastle Disease and aMPV Live Vaccines to Day-Old Turkeys
Newcastle disease virus (NDV) and avian metapneumovirus (aMPV) are among the most impactful pathogens affecting the turkey industry. Since turkeys are routinely immunized against both diseases, the hatchery administration of the combined respective live vaccines would offer remarkable practical advantages. However, the compatibility of NDV and aMPV vaccines has not yet been experimentally demonstrated in this species. To address this issue, an aMPV subtype B live vaccine was administered to day-old poults either alone or in combination with one of two different ND vaccines. The birds were then challenged with a virulent aMPV subtype B strain, clinical signs were recorded and aMPV and NDV vaccine replication and humoral immune response were assessed. All results supported the absence of any interference hampering protection against aMPV, with no significant differences in terms of clinical scoring. In addition, the mean aMPV vaccine viral titers and antibody titers measured in the dual vaccinated groups were comparable or even higher than in the group vaccinated solely against aMPV. Lastly, based on the NDV viral and antibody titers, the combined aMPV and NDV vaccination does not seem to interfere with protection against NDV, although further studies involving an actual ND challenge will be necessary to fully demonstrate this hypothesis
Vaccine or field strains: the jigsaw pattern of infectious bronchitis virus molecular epidemiology in Poland
Infectious bronchitis (IB), caused by infectious bronchitis virus (IBV), account for severe economic losses in the poultry industry. The continuous emergence of a multitude of IBV variants poses many challenges for its diagnosis and control, and live attenuated vaccines, despite their routine use, still plays a significant role in driving IBV evolution, further complicating the epidemiological scenario. Unfortunately, the impact of different vaccination strategies on IB control, epidemiology, and diagnosis has rarely been investigated. This work presents the results of a large-scale diagnostic survey performed in Poland to study IBV molecular epidemiology and how vaccination may affect the viral circulation in the field. To this purpose, 589 samples were collected between May 2017 and January 2019, tested by reverse transcription-PCR for IBV and sequenced. Vaccine and field strains were discriminated based on genetic and anamnestic information. The most commonly detected lineages were 793B (79%) and variant 2 (17.4%), with sporadic detections of QX, Mass, and D274-like strains. Most of the detected strains had a vaccine origin: 46.3% matched one of the applied vaccines, while 36.5% were genetically related to vaccines not implemented in the respective protocol. Besides their practical value for the proper planning of vaccination protocols in Poland, these results suggest that only a fraction (17.2%) of the circulating strains are field ones, imposing a careful assessment of the actual IBV field menaces. Moreover, phenomena like vaccine spreading and persistence seem to occur commonly, stressing the need to further study the epidemiological consequences of the extensive use of live vaccines
A Shift in Porcine Circovirus 3 (PCV-3) History Paradigm: Phylodynamic Analyses Reveal an Ancient Origin and Prolonged Undetected Circulation in the Worldwide Swine Population
The identification of a new circovirus (Porcine circovirus 3, PCV-3) has raised a remarkable concern because of some analogies with Porcine circovirus 2 (PCV-2). Preliminary results suggest an extremely recent PCV-3 emergence and high mutation rate. Retrospective studies prove its circulation at least since the early 1990s, revealing that PCV-3 could have been infecting pigs for an even longer period. Therefore, a new evaluation, based on an updated collection of PCV-3 sequences spanning more than 20 years, is performed using a phylodynamic approach. The obtained results overrule the previous PCV-3 history concept, indicating an ancient origin. These evidences are associated with an evolutionary rate far lower (10-10 substitution/site/year) than the PCV-2 one. Accordingly, the action of selective pressures on PCV-3 open reading frames (ORFs) seems to be remarkably lower compared to those acting on PCV-2, suggesting either a reduced PCV-3 plasticity or a less efficient host-induced natural selection. A complex and not-directional viral flow network is evidenced through phylogeographic analysis, indicating a long lasting circulation rather than a recent emergence followed by spreading. Being recent emergence has been ruled out, efforts should be devoted to understand whether its recent discovery is simply due to improved detection capabilities or to the breaking of a previous equilibrium
Differential reddening in the direction of 56 Galactic globular clusters
The presence of differential reddening in the direction of Galactic globular
clusters (GCs) has proven to be a serious limitation in the traditional
colour-magnitude diagram (CMD) analysis. Here, we estimate local reddening
variations in the direction of 56 Galactic GCs. To do that, we use the public
catalogs derived as part of the Hubble Space Telescope UV Legacy Survey of
Galactic Globular Clusters, which include photometry in the F275W, F336W,
F438W, F606W, and F814W filters. We correct photometry for differential
reddening finding that for 21 out of 56 GCs the adopted correction procedure
significantly improves the CMDs. Moreover, we measure the reddening law in the
direction of these clusters finding that exhibits a high level of
variability within the Galaxy, ranging from to . The updated
values of have been used to improve the determination of local
reddening variations and derive high-resolution reddening maps in the direction
of the 21 highly-reddened targets within our sample. To compare the results of
the different clusters, we compute the 68 percentile of the
differential-reddening distribution, . This
quantity ranges from 0.003 mag to 0.030 mag and exhibits a significant
anti-correlation with the absolute module of the Galactic latitude and a strong
correlation with the average reddening in the direction of each cluster.
Therefore, highly-reddened GCs located in the proximity of the Galactic plane
typically show higher differential-reddening variations across their field of
view.Comment: 14 pages, 14 figures, accepted for pubblication in MNRAS. The
photometric catalogs corrected for differential reddening are publicly
available at this website: http://progetti.dfa.unipd.it/GALFOR
Multiple Stellar Populations in Globular Clusters with JWST: a NIRCam view of 47 Tucanae
We use images collected with the near-infrared camera (NIRCam) on board the
James Webb Space Telescope and with the Hubble Space Telescope (HST) to
investigate multiple populations at the bottom of the main sequence (MS) of 47
Tucanae. The F115W vs. F115W-F322W2 CMD from NIRCam shows that, below the knee,
the MS stars span a wide color range, where the majority of M-dwarfs exhibit
blue colors, and a tail of stars are distributed toward the red. A similar
pattern is observed from the F160W vs. F110W-F160W CMD from HST, and multiple
populations of M-dwarfs are also visible in the optical F606W vs. F606W-F814W
CMD. The NIRCam CMD shows a poorly-populated sequence of faint MS stars that we
tentatively associate with a population of very low-mass stars. We introduce a
chromosome map of M-dwarfs that reveals an extended first population and three
main groups of second-population stars. By combining isochrones and synthetic
spectra with appropriate chemical composition, we simulate colors and
magnitudes of different stellar populations in the NIRCam filters (at
metallicities [Fe/H]=-1.5 and [Fe/H]=-0.75) and identify the photometric bands
that provide the most efficient diagrams to investigate the multiple
populations in globular clusters. Models are compared with the observed CMDs of
47 Tucanae to constrain M-dwarfs' chemical composition. Our analysis suggests
that the oxygen range needed to reproduce the colors of first- and
second-population M-dwarfs is similar to that inferred from spectroscopy of red
giants, challenging the proposal that the chemical variations are due to mass
transfer phenomena in proto-clusters.Comment: 16 pages, 13 figures, submitte
Fullâgenome sequencing of porcine circovirus 3 field strains from Denmark, Italy and Spain demonstrates a high withinâEurope genetic heterogeneity
Porcine circovirus 3 (PCV3) is a new species of the Circovirus genus, which has recently been associated with different clinical syndromes. Its presence has been reported in different countries of North and South America, Asia and recently also Europe (Poland). However, different from the other continents, no European PCV3 sequence is currently available in public databases. There is a strong need of epidemiological data and full-genome sequences from Europe because of its relevance in the understanding of PCV3 molecular epidemiology and control. To fill this lack of information, samples collected in Denmark, Italy and Spain in 2016 and 2017 were screened for PCV3. Of the Danish samples, 36 of 38 the lymph nodes, six of 20 serum samples and two of 20 lung samples tested positive. Similarly, 10 of 29 lungs, 20 of 29 organ pools, six of 33 sera and one of eight nasal swabs tested PCV3 positive in Italy. Fourteen of 94 serum pools from seven of 14 Spanish farms were also positive. Despite the convenience nature of the sampling prevents any precise prevalence estimation, the preliminary screening of the data from three European countries confirmed a rather wide PCV3 distribution in Europe. Furthermore, the analysis of the six obtained complete European PCV3 genomes and their comparison with the public available sequences seems to support a remarkable worldwide PCV3 circulation. These results underline once more the urgency of more extensive epidemiological studies to refine the current knowledge on PCV3 evolution, transmission, spreading patterns and impact on pig health.info:eu-repo/semantics/acceptedVersio
Mass loss law for red giant stars in simple population globular clusters
The amount of mass lost by stars during the red-giant branch (RGB) phase is
one of the main parameters to understand and correctly model the late stages of
stellar evolution. Nevertheless, a fully-comprehensive knowledge of the RGB
mass loss is still missing.
Galactic Globular Clusters (GCs) are ideal targets to derive empirical
formulations of mass loss, but the presence of multiple populations with
different chemical compositions has been a major challenge to constrain stellar
masses and RGB mass losses. Recent work has disentangled the distinct stellar
populations along the RGB and the horizontal branch (HB) of 46 GCs, thus
providing the possibility to estimate the RGB mass loss of each stellar
population. The mass losses inferred for the stellar populations with pristine
chemical composition (called first-generation or 1G stars) tightly correlate
with cluster metallicity. This finding allows us to derive an empirical RGB
mass-loss law for 1G stars.
In this paper we investigate seven GCs with no evidence of multiple
populations and derive the RGB mass loss by means of high-precision {\it
Hubble-Space Telescope} photometry and accurate synthetic photometry.
We find a cluster-to-cluster variation in the mass loss ranging from
0.1 to 0.3 .
The RGB mass loss of simple-population GCs correlates with the metallicity of
the host cluster. The discovery that simple-population GCs and 1G stars of
multiple population GCs follow similar mass-loss vs. metallicity relations
suggests that the resulting mass-loss law is a standard outcome of stellar
evolution.Comment: 10 pages, 7 figures, 3 tables, accepted for publication on MNRA
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