Draft Genome Sequences of Six Ruminant Coxiella burnetii Isolates of European Origin

Coxiella burnetii is responsible for Q fever, a worldwide zoonosis attributed to the inhalation of aerosols contaminated by livestock birth products. Six draft genome sequences of European C. burnetii isolates from ruminants are presented here. The availability of these genomes will help in understanding the potential host specificity and pathogenicity and in identifying pertinent markers for surveillance and tracing

Characterisation of Structural Proteins from Chronic Bee Paralysis Virus (CBPV) Using Mass Spectrometry

International audienceChronic bee paralysis virus (CBPV) is the etiological agent of chronic paralysis, an infectious and contagious disease in adult honeybees. CBPV is a positive single-stranded RNA virus which contains two major viral RNA fragments. RNA 1 (3674 nt) and RNA 2 (2305 nt) encode three and four putative open reading frames (ORFs), respectively. RNA 1 is thought to encode the viral RNA-dependent RNA polymerase (RdRp) since the amino acid sequence derived from ORF 3 shares similarities with the RdRP of families Nodaviridae and Tombusviridae. The genomic organization of CBPV and in silico analyses have suggested that RNA 1 encodes non-structural proteins, while RNA 2 encodes structural proteins, which are probably encoded by ORFs 2 and 3. In this study, purified CBPV particles were used to characterize virion proteins by mass spectrometry. Several polypeptides corresponding to proteins encoded by ORF 2 and 3 on RNA 2 were detected. Their role in the formation of the viral capsid is discussed

Development and validation of a real-time two-step RT-qPCR TaqMan (R) assay for quantitation of Sacbrood virus (SBV) and its application to a field survey of symptomatic honey bee colonies

Sacbrood virus (SBV) is the causal agent of a disease of honey bee larvae, resulting in failure to pupate and causing death. The typical clinical symptom of SBV is an accumulation of SBV-rich fluid in swollen subcuticular pouches, forming the characteristic fluid-filled sac that gives its name to the disease. Outbreaks of the disease have been reported in different countries, affecting the development of the brood and causing losses in honey bee colonies. Today, few data are available on the SBV viral load in the case of overt disease in larvae, or for the behavioural changes of SBV-infected adult bees. A two-step real-time RT-PCR assay, based on TaqMan (R) technology using a fluorescent probe (FAM-TAMRA) was therefore developed to quantify Sacbrood virus in larvae, pupae and adult bees from symptomatic apiaries. This assay was first validated according to the recent XP-U47-600 standard issued by the French Standards Institute, where the reliability and the repeatability of the results and the performance of the assay were confirmed. The performance of the qPCR assay was validated over the 6 log range of the standard curve (i.e. from 10(2) to 10(8) copies per well) with a measurement uncertainty evaluated at 0.11 log(10). The detection and quantitation limits were established respectively at 50 copies and 100 copies of SBV genome, for a template volume of 5 mu l of cDNA. The RT-qPCR assay was applied during a French SBV outbreak in 2012 where larvae with typical SBV signs were collected, along with individuals without clinical signs. The SBV quantitation revealed that, in symptomatic larvae, the virus load was significantly higher than in samples without clinical signs. Combining quantitation with clinical data, a threshold of SBV viral load related to an overt disease was proposed (10(10) SBV genome copies per individual)

Influence of chronic exposure to thiamethoxam and chronic bee paralysis virus on winter honey bees.

Co-exposure to pesticides and viruses is likely to occur in honey bee colonies. Pesticides can be present in pollen, nectar, and persist in stored food (honey and bee bread), and viruses can be highly prevalent in honey bee colonies. Therefore, the present study describes the influence of chronic co-exposure to thiamethoxam and Chronic bee paralysis virus (CBPV) on bee survival, virus loads, expression level of immune and detoxication genes, and pesticide metabolism Experiments were performed on honey bees collected from a winter apiary with reduced viral contaminations. No synergistic effect of co-exposure was observed on bee survival, nor on the ability of bees to metabolise the pesticide into clothianidin. However, we found that co-exposure caused an increase in CBPV loads that reached the viral levels usually found in overt infections. The effect of co-exposure on CBPV replication was associated with down-regulation of vitellogenin and dorsal-1a gene transcription. Nevertheless, the observed effects might be different to those occurring in spring or summer bees, which are more likelyco-exposed to thiamethoxam and CBPV and exhibit a different physiology

Staphylococcus aureus seroproteomes discriminate ruminant isolates causing mild or severe mastitis

Staphylococcus aureus is a major cause of mastitis in ruminants. In ewe mastitis, symptoms range from subclinical to gangrenous mastitis. S. aureus factors or host-factors contributing to the different outcomes are not completely elucidated. In this study, experimental mastitis was induced on primiparous ewes using two S. aureus strains, isolated from gangrenous (strain O11) or subclinical (strain O46) mastitis. Strains induced drastically distinct clinical symptoms when tested in ewe and mice experimental mastitis. Notably, they reproduced mild (O46) or severe (O11) mastitis in ewes. Ewe sera were used to identify staphylococcal immunoreactive proteins commonly or differentially produced during infections of variable severity and to define core and accessory seroproteomes. Such SERological Proteome Analysis (SERPA) allowed the identification of 89 immunoreactive proteins, of which only 52 (58.4%) were previously identified as immunogenic proteins in other staphylococcal infections. Among the 89 proteins identified, 74 appear to constitute the core seroproteome. Among the 15 remaining proteins defining the accessory seroproteome, 12 were specific for strain O11, 3 were specific for O46. Distribution of one protein specific for each mastitis severity was investigated in ten other strains isolated from subclinical or clinical mastitis. We report here for the first time the identification of staphylococcal immunogenic proteins common or specific to S. aureus strains responsible for mild or severe mastitis. These findings open avenues in S. aureus mastitis studies as some of these proteins, expressed in vivo, are likely to account for the success of S. aureus as a pathogen of the ruminant mammary gland

Molecular Basis of Virulence in Staphylococcus aureus Mastitis

S. aureus is one of the main pathogens involved in ruminant mastitis worldwide. The severity of staphylococcal infection is highly variable, ranging from subclinical to gangrenous mastitis. This work represents an in-depth characterization of S. aureus mastitis isolates to identify bacterial factors involved in severity of mastitis infection

Host plant cultivar of the grapevine moth Lobesia botrana affects the life history traits of an egg parasitoid.

6 pagesInternational audienceThe quality and susceptibility of insect eggs for egg parasitoids may be affected by the diet experienced by the females that produce the host eggs. We tested the hypothesis that the host plant fed upon by an herbivore during the larval stages will determine the quality of the eggs laid by the adult for an egg parasitoid. We used the tritrophic system comprising five grape cultivars, the European grapevine moth, Lobesia botrana and the parasitoid Trichogramma evanescens. Parasitoid performance in host eggs of different sizes and originating from five grape cultivars was determined. Overall, egg parasitism was higher on cultivars on which L. botrana laid larger eggs, which resulted in higher larval survival and faster development time of the wasps. One exception was found for the cultivar Pinot. Trichogramma wasps parasitized fewer eggs originating from females that fed on the Pinot cultivar as larvae despite good progeny performance (high survival and fast development time). The poor motivation of the parasitoid to oviposit in ‘‘Pinot” eggs could be a result of deterrence due to plant compounds ingested by the moth as a larva and transferred to the eggs, or lack of plant-derived compounds that stimulate oviposition in the parasitoid. Interestingly, within a cultivar, Trichogramma larval survivorship was higher in younger, smaller eggs than in older, larger ones. This effect however is confounded by the effect of the plant cultivar, since the host egg size varies among grape varieties. Overall, the results of this study support the hypothesis that an herbivore's host plant can influence the performance of its egg parasitoids

Quantitative assessment of the saturation degree of model fine recycled concrete aggregates immersed in a filler or cement paste

\textcopyright 2018 We study water transfer between different model fine recycled concrete aggregates and fresh filler or cement paste in which they are immersed. Our aim is to introduce a spread based experimental protocol for studying the time evolution of water content in initially dry aggregates when mixed with such pastes. The procedure developed hereby is tested on three model Cement Paste Sands (CPS) prepared with different water-to-cement ratios leading to very different porosities and pore structures. The results show that water content in the CPS reaches a maximum no later than 6 min after first contact with limestone filler or cement paste then remains fairly constant afterwards. The saturation degree, i.e. ratio of the water content in the CPS to their water absorption, increases with the porosity of the CPS and remains less than one whatever the paste. The corresponding reduction of water absorption capacity in a cement paste should be taken into account during mix design of a recycled concrete