Assessment of real aging in selection process of replacement materials for stone monuments conservation

[EN] Reconstruction of monuments often raises the question of stones replacement. It must be aesthetically durable, which means the stone must age like the original one. This study presents an image processing chain, from capture to visualisation, to compare stones at different states of aging: recently extracted from quarry, weathered on old buildings, and cleaned on monuments recently restored. This tool includes: (1) a digital still camera calibration, (2) a chromatic adaptation transform and (3) a resizing process. To test it, a case study was conducted to assess the compatibility of three types of limestone. This graphical tool helps the selection of replacement materials by visual comparison between several possible stones in order to select them by aging properties and visual resemblance.[ES] En el ámbito de la sustitución de piedras en los monumentos, frecuentemente se plantea el problema de la selección de las piedras de reemplazo. De hecho, la reconstrucción debe ser estéticamente duradera, es decir, la piedra sustituida debe envejecer como la piedra original. Este estudio presenta una cadena de procesamiento de imágenes, desde la adquisición hasta la visualización, que permite comparar imágenes de piedras en varias etapas de su envejecimiento: recién extraída de la cantera, envejecida en edificios antiguos, y decapada con arena en monumentos recién restaurados. Esta herramienta incluye: (1) una calibración de cámara digital, (2) una transformación de adaptación cromática y (3) una etapa de redimensión. Para testear el método propuesto, un estudio de caso se llevó a cabo para evaluar la compatibilidad de tres tipos de caliza. Esta herramienta gráfica puede ayudar la selección de materiales de reemplazo con envejecimiento complejo como la piedra natural.Concha Lozano, N.; Lafon, D.; Eterradossi, O.; Gaudon, P. (2011). Assessment of real aging in selection process of replacement materials for stone monuments conservation. Virtual Archaeology Review. 2(3):27-31. https://doi.org/10.4995/var.2011.4579OJS273123BRILL, Michael H., "The relation between the color of the illuminant and the color of the illuminated object". Color Research & Application. (1995) 20: 70- 5. doi:10.1002/col.5080200112.)CHORRO E., PERALES E., de Fez D., LUQUE M. J., and MARTÍNEZ-VERDÚ F. M., "Application of the S-CIELAB color model to processed and calibrated images with a colorimetric dithering method," Optics Express 15, no. 12 (Juin 11, 2007): 7810-7817. http://dx.doi.org/10.1364/OE.15.007810FAIRCHILD M.D., "A Revision of CIECAM97s for Practical Applications ", dans Color Research & Applications, Wiley Interscience, vol. 25, no 4, August 2000, p. 260-266ICOMOS-ISCS, Illustrated glossary on stone deterioration patterns, 2008THORNBUSH. M.J. and VILES, H.A., "Photo-based decay mapping of replaced stone blocks on the boundary wall of Worcester College, Oxford". Building stone decay: from diagnosis to conservation. In, Prikryl, R. and Smith, B.J. (eds.) (2007) Geological Society Special Publication, 271: 69-75.P.THORNBUSH. M.J., "Grayscale calibration of outdoor photographic surveys of historical Stone Walls in Oxford, England," Color Research & Application 33, no. 1 (2, 2008): 61-67.STOKES M. (Hewlett-Packard), ANDERSON M. (Microsoft), CHANDRASEKAR S. (Microsoft), MOTTA R. (Hewlett-Packard) Version 1.10, November 5, 1996 "A Standard Default Color Space for the Internet: sRGB" ICC, [online] http://www.color.org/sRGB.xalter [Consulta: 22-04-2010]

Blood B Cell Depletion Reflects Immunosuppression Induced by Live-Attenuated Infectious Bursal Disease Vaccines

Immunosuppression in poultry production is a recurrent problem worldwide, and one of the major viral immunosuppressive agents is Infectious Bursal Disease Virus (IBDV). IBDV infections are mostly controlled by using live-attenuated vaccines. Live-attenuated Infectious Bursal Disease (IBD) vaccine candidates are classified as “mild,” “intermediate,” “intermediate-plus” or “hot” based on their residual immunosuppressive properties. The immunosuppression protocol described by the European Pharmacopoeia (Ph. Eur.) uses a lethal Newcastle Disease Virus (NDV) infectious challenge to measure the interference of a given IBDV vaccine candidate on NDV vaccine immune response. A Ph. Eur.-derived protocol was thus implemented to quantify immunosuppression induced by one mild, two intermediate, and four intermediate-plus live-attenuated IBD vaccines as well as a pathogenic viral strain. This protocol confirmed the respective immunosuppressive properties of those vaccines and virus. In the search for a more ethical alternative to Ph. Eur.-based protocols, two strategies were explored. First, ex vivo viral replication of those vaccines and the pathogenic strain in stimulated chicken primary bursal cells was assessed. Replication levels were not strictly correlated to immunosuppression observed in vivo. Second, changes in blood leukocyte counts in chicks were monitored using a Ph. Eur. - type protocol prior to lethal NDV challenge. In case of intermediate-plus vaccines, the drop in B cells counts was more severe. Counting blood B cells may thus represent a highly quantitative, faster, and ethical strategy than NDV challenge to assess the immunosuppression induced in chickens by live-attenuated IBD vaccines

Different Domains of the RNA Polymerase of Infectious Bursal Disease Virus Contribute to Virulence

BACKGROUND: Infectious bursal disease virus (IBDV) is a pathogen of worldwide significance to the poultry industry. IBDV has a bi-segmented double-stranded RNA genome. Segments A and B encode the capsid, ribonucleoprotein and non-structural proteins, or the virus polymerase (RdRp), respectively. Since the late eighties, very virulent (vv) IBDV strains have emerged in Europe inducing up to 60% mortality. Although some progress has been made in understanding the molecular biology of IBDV, the molecular basis for the pathogenicity of vvIBDV is still not fully understood. METHODOLOGY, PRINCIPAL FINDINGS: Strain 88180 belongs to a lineage of pathogenic IBDV phylogenetically related to vvIBDV. By reverse genetics, we rescued a molecular clone (mc88180), as pathogenic as its parent strain. To study the molecular basis for 88180 pathogenicity, we constructed and characterized in vivo reassortant or mosaic recombinant viruses derived from the 88180 and the attenuated Cu-1 IBDV strains. The reassortant virus rescued from segments A of 88180 (A88) and B of Cu-1 (BCU1) was milder than mc88180 showing that segment B is involved in 88180 pathogenicity. Next, the exchange of different regions of BCU1 with their counterparts in B88 in association with A88 did not fully restore a virulence equivalent to mc88180. This demonstrated that several regions if not the whole B88 are essential for the in vivo pathogenicity of 88180. CONCLUSION, SIGNIFICANCE: The present results show that different domains of the RdRp, are essential for the in vivo pathogenicity of IBDV, independently of the replication efficiency of the mosaic viruses

Infectious Bronchitis Coronavirus: Genome Evolution in Vaccinated and Non-Vaccinated SPF Chickens

Infectious Bronchitis virus (IBV) continues to cause significant economic losses for the chicken industry despite the use of many live IBV vaccines around the world. Several authors have suggested that vaccine-induced partial protection may contribute to the emergence of new IBV strains. In order to study this hypothesis, three passages of a challenge IBV were made in SPF chickens sham inoculated or vaccinated at day of age using a live vaccine heterologous to the challenge virus. All birds that were challenged with vaccine heterologous virus were positive for viral RNA. NGS analysis of viral RNA in the unvaccinated group showed a rapid selection of seven genetic variants, finally modifying the consensus genome of the viral population. Among them, five were non-synonymous, modifying one position in NSP 8, one in NSP 13, and three in the Spike protein. In the vaccinated group, one genetic variant was selected over the three passages. This synonymous modification was absent from the unvaccinated group. Under these conditions, the genome population of an IBV challenge virus evolved rapidly in both heterologous vaccinated and non-vaccinated birds, while the genetic changes that were selected and the locations of these were very different between the two groups

Genome Evolution of Two Genetically Homogeneous Infectious Bursal Disease Virus Strains During Passages in vitro and ex vivo in the Presence of a Mutagenic Nucleoside Analog

The avibirnavirus infectious bursal disease virus (IBDV) is responsible for a highly contagious and sometimes lethal disease of chickens (Gallus gallus). IBDV genetic variation is well-described for both field and live-attenuated vaccine strains, however, the dynamics and selection pressures behind this genetic evolution remain poorly documented. Here, genetically homogeneous virus stocks were generated using reverse genetics for a very virulent strain, rvv, and a vaccine-related strain, rCu-1. These viruses were serially passaged at controlled multiplicities of infection in several biological systems, including primary chickens B cells, the main cell type targeted by IBDV in vivo. Passages were also performed in the absence or presence of a strong selective pressure using the antiviral nucleoside analog 7-deaza-2′-C-methyladenosine (7DMA). Next Generation Sequencing (NGS) of viral genomes after the last passage in each biological system revealed that (i) a higher viral diversity was generated in segment A than in segment B, regardless 7DMA treatment and viral strain, (ii) diversity in segment B was increased by 7DMA treatment in both viruses, (iii) passaging of IBDV in primary chicken B cells, regardless of 7DMA treatment, did not select cell-culture adapted variants of rvv, preserving its capsid protein (VP2) properties, (iv) mutations in coding and non-coding regions of rCu-1 segment A could potentially associate to higher viral fitness, and (v) a specific selection, upon 7DMA addition, of a Thr329Ala substitution occurred in the viral polymerase VP1. The latter change, together with Ala270Thr change in VP2, proved to be associated with viral attenuation in vivo. These results identify genome sequences that are important for IBDV evolution in response to selection pressures. Such information will help tailor better strategies for controlling IBDV infection in chickens

Bases moléculaires du pouvoir pathogène et développement d une méthode de quantification différentielle des quatre brinsgénomiques chez l Avibirnavirus de la bursite infectieuse

La bursite infectieuse est une maladie des jeunes poulets (espèce Gallus gallus) provoquée par un virus (IBDV, famille Birnaviridae, genre Avibirnavirus) à génome bisegmenté (A & B) composé d ARN double-brin. Le cycle viral est peu documenté concernant le moment et le lieu de synthèse des brins positifs et négatifs. Dans une première partie de cette étude, une technique de RT-PCR quantitative en temps réel spécifique de chacun des brins des deux segments a été développée. L application de celle-ci à des particules virales d IBDV purifiées ainsi qu à une cinétique de production de brins in-vitro renseigne respectivement sur le contenu génomique du virus ainsi que sur son mode de réplication. Ces résultats suggèrent, entre autres, que la synthèse des brins négatifs ne survient qu après le recrutement équimolaire des brins positifs A et B au sein de la particule virale. Dans une deuxième partie, les bases moléculaires du pouvoir pathogène ont été étudiées, le niveau de pathogénicité des souches étant variable et pouvant se traduire par une forte mortalité pour les souches les plus virulentes (vvIBDV). Cependant, aucun marqueur de pathogénicité n est clairement identifié. L étude s est effectuée à partir d un isolat (94432) faiblement pathogène (faible morbidité, pas de mortalité) malgré un génome phylogéniquement apparenté aux vvIBDV. Par la génétique inverse, des virus recombinants dérivés de 94432 ont été caractérisés in-vivo. Les résultats obtenus permettent de documenter un rôle important de la polymérase virale (codée par B) dans la réduction du pouvoir pathogène de 94432, et notamment de l acide aminé en position 276 dont l implication biologique est encore inconnue.Infectious Bursal Disease (IBD) is an infectious disease of young chickens (Gallus gallus) caused by a bisegmented (A & B) double-stranded RNA genome virus (IBDV, family Birnaviridae, genus Avibirnavirus). The virus replication cycle is not fully described regarding the time and place of strand synthesis. In a first part of this study, four real-time quantitative RT-PCR methods, able to quantify specifically each strand of the IBDV genome, were developed. Implementation of these methods on purified IBDV particles and on a kinetic study of in-vitro strand production provided interesting data as to the possible genomic content of virus particles and to the replication model, respectively. These results suggest that negative strand synthesis occurs after equimolar positive strand (A & B) packaging inside nascent virus particle. Molecular basis of the pathogenicity have been investigated in a second study. Very virulent IBDV strain (vvIBDV) can induce important clinical sign and mortality rates but no reliable molecular marker has been definitely identified yet. This study was carried out on a field strain (94432) which, in spite of being phylogenetically related to vvIBDVs, does not induce any mortality and only low morbidity in chickens. Using a reverse genetic system associated to 94432, several recombinant derived-94432 viruses were characterized in-vivo. Results demonstrated an important contribution of the polymerase encoded-segment B, especially of one amino acid at position 276, in the reduced pathogenicity of 94432. The biological function of amino acid 276 remains unknown.RENNES1-BU Sciences Philo (352382102) / SudocSudocFranceF

Étude de l'épidémiologie moléculaire du segment B de l'avibinavirus de la bursite infectieuse aviaire et bases moléculaires de la virulence chez ce virus

La bursite infectieuse est une maladie du poulet (Gallus gallus) causée par un virus (noté IBDV) de la famille des Birnaviridae, genre Avibirnavirus. Certaines souches d'IBDV dites hypervirulentes (vvIBDV) induisent une mortalité supérieure à 30 %. Il n'y a pas de marqueur génétique de virulence pour les caractériser. Afin de comparer l'épidémiologie moléculaires des deux segments génomiques de l'IBDV, notés A et B, de courtes régions génomiques phylogénétiquement représentatives de chacun des segments ont éte identifiées, en comparant les phylogénies dérivées de séquences nucléotidiques complètes ou partielles déjà publiées. Ces régions correspondent au tiers moyen du gène VP2 (segment A) et aux deux tiers 5' du gène VP1 (segment B). Ces régions ont été amplifiées et séquencées chez 50 souches virales d'origines et de phénotypes variés. Leur étude phylogénétique suggère que les segments génomiques ont co-évolué chez 70 % des virus étudiés (dont les vvIBDV), mais que des phénomènes de réassortiment pourraient avoir affecté 13 % des souches virales. Un des virus potentiellement réassortant (segment A apparenté aux vvIBDV, segment B non vvIBDV), inoculé expérimentalement à des poulets sensibles, avait un pouvoir pathogène réduit sans que la réplication virale apparaisse modifiée. Les bases moléculaires de la pathogénicité de l'IBDV ont finalement été recherchées chez deux souches virales apparentées aux vvIBDV identifiées lors de l'étude phylogénétique, l'une issue d'une lignée particulière de virus pathogènes (88180), l'autre apparentée aux vvIBDV typiques mais dotée d'un pouvoir pathogène réduit (94432). Un système de génétique inverse a été développé pour chacune. Le pouvoir pathogène in vivo des clones moléculaires correspondants s'est avéré comparable à celui des virus parentaux. Onze virus génétiquement modifiés dérivés des clones moléculaires ont été construits et caractérisés in vivo. Le pouvoir pathogène de 88180 semble lié au segment A et à plusieurs régions du segment B, alors que l'atténuation de 94432 s'avère liée à trois mutations peptidiques codées par le segment A.LYON1-BU.Sciences (692662101) / SudocSudocFranceF

Infectious bursal disease virus: predicting viral pathotype using machine learning models focused on early changes in total blood cell counts

Abstract Infectious bursal disease (IBD) is an avian viral disease caused in chickens by infectious bursal disease virus (IBDV). IBDV strains (Avibirnavirus genus, Birnaviridae family) exhibit different pathotypes, for which no molecular marker is available yet. The different pathotypes, ranging from sub-clinical to inducing immunosuppression and high mortality, are currently determined through a 10-day-long animal experiment designed to compare mortality and clinical score of the uncharacterized strain with references strains. Limits of this protocol lie within standardization and the extensive use of animal experimentation. The aim of this study was to establish a predictive model of viral pathotype based on a minimum number of early parameters measured during infection, allowing faster pathotyping of IBDV strains with improved ethics. We thus measured, at 2 and 4 days post-infection (dpi), the blood concentrations of various immune and coagulation related cells, the uricemia and the infectious viral load in the bursa of Fabricius of chicken infected under standardized conditions with a panel of viruses encompassing the different pathotypes of IBDV. Machine learning algorithms allowed establishing a predictive model of the pathotype based on early changes of the blood cell formula, whose accuracy reached 84.1%. Its accuracy to predict the attenuated and strictly immunosuppressive pathotypes was above 90%. The key parameters for this model were the blood concentrations of B cells, T cells, monocytes, granulocytes, thrombocytes and erythrocytes of infected chickens at 4 dpi. This predictive model could be a second option to traditional IBDV pathotyping that is faster, and more ethical

Etude in vivo du transfert de la mélamine vers certaines productions avicoles, notamment oeufs et viande

Etude in vivo du transfert de la mélamine vers certaines productions avicoles, notamment oeufs et viand