Search

Het aantal omgevingsgebonden mastitisverwekkers in de tankmelk neemt de laatste jaren toe, dat laten de resultaten van ons tankmelkprogramma Mastitis Tankmelk zien. Omgevingsgebonden mastitisverwekkers komen altijd in de omgeving (stal, weide) van de koe voor. Hoe voorkom je explosieve groei van deze kiemen, zeker in de zomer?

Griepvirussen vieren hoogtij in periodes met koud, vochtig weer en weinig ultraviolet licht. Toch ziet Eric van Esch de grens van het griepseizoen in de varkenshouderij vervagen. ‘Vooral op bedrijven met zeugen en biggen kan het influenzavirus jaarrond circuleren en veel schade aanrichten. Neem griep daarom serieus!’

Europa heeft er een tropisch virus bij. Het EHD-virus (epizootic haemorrhagic disease), dat hier eind 2022 voor het eerst opdook, behoort tot dezelfde familie virussen als blauwtong en is al even bedreigend voor rundvee. Langzaamaan verspreidt het virus zich over het continent richting het noorden. Diergezondheidsorganisaties in Nederland en Vlaanderen houden een oogje in het zeil. ‘Schapen zijn weinig tot niet gevoelig voor ziekte door het EHD-virus. Vooral herten en ook runderen kunnen ernstig ziek worden van dit virus.’

Besmette rammen en stieren kunnen de het blauwtongvirus overdragen op vatbare ooien en koeien. Dierenartsen René van der Brom en Piet Vellema raden aan om behoedzaam te zijn tijdens het dekseizoen.

De blauwtonguitbraak leidt niet alleen tot veel sterfte onder schapen, ook werpt de ziekte een schaduw over het dekseizoen. Bij de kleine rassen – getalsmatig, niet qua formaat – kan dat problemen geven: komt hun voortbestaan in gevaar? Resource sprak erover met Annemieke Rattink en Noelle Hoorneman van het Centrum voor Genetische Bronnen Nederland (CGN).

De kans dat het blauwtongvirus (BTV-3) deze winter op de een of andere manier overwintert is aanwezig. Maar het is volgens deskundigen Armin Elbers, Melle Holwerda en Piet van Rijn van Wageningen Bioveterinary Research heel lastig aan te tonen hoe het virus overwintert.

De ziekmakende PRRS-veldvirussen die overal in Nederland rondwaren, krijgen op De Schanshoeve geen kans. Met goed management, strikte bioveiligheid en de juiste vaccinatie houdt bedrijfsleider Ramon Katoele de veldvirussen al jaren buiten de deur.

Animal intestines are the source of edible sausage casings, which are traded worldwide and may come from areas where notifiable infectious animal diseases are prevalent. To estimate the risks of virus contamination, knowledge about the quantity of virus and decimal reduction values of the standard preservation method by salting is of great importance. A literature search, based on the Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA) guidelines, was performed in search engine CAB Abstracts to determine the viral load of 14 relevant animal viruses in natural casings or intestines. Only a very limited number of scientific publications per virus were found and viral loads in the intestines varied from high for ASFV (five publications), BVDV (3), CSFV (6), PPRV (3), RPV(2) and TGEV (3) to moderate for PEDV (2) and SVDV (3), low for HEV (2) and FMDV (5), very low for VESV (1) and negative for PrV (2) and VSV (1). PRRSV was found in intestines, however, viral titers were not published. Three viruses (BVDV, CSFV and PPRV) with high viral loads were selected to search for their inactivation kinetics. For casings, no inactivation data were found, however, thermal inactivation data of these viruses were available, but differed in quantity, quality and matrices. In conclusion, important data gaps still exist when it comes to the quantitative inactivation of viruses in sausage casings or livestock intestines.

Animal intestines are the source of edible sausage casings, which are traded worldwide and may come from areas where notifiable infectious animal diseases are prevalent. To estimate the risks of virus contamination, knowledge about the quantity of virus and decimal reduction values of the standard preservation method by salting is of great importance. A literature search, based on the Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA) guidelines, was performed in search engine CAB Abstracts to determine the viral load of 14 relevant animal viruses in natural casings or intestines. Only a very limited number of scientific publications per virus were found and viral loads in the intestines varied from high for ASFV (five publications), BVDV (3), CSFV (6), PPRV (3), RPV (2) and TGEV (3) to moderate for PEDV (2) and SVDV (3), low for HEV (2) and FMDV (5), very low for VESV (1) and negative for PrV (2) and VSV (1). PRRSV was found in intestines, however, viral titers were not published. Three viruses (BVDV, CSFV and PPRV) with high viral loads were selected to search for their inactivation kinetics. For casings, no inactivation data were found, however, thermal inactivation data of these viruses were available, but differed in quantity, quality and matrices. In conclusion, important data gaps still exist when it comes to the quantitative inactivation of viruses in sausage casings or livestock intestines.

Trait variation within species is shaped by the genotype and the environment an individual is exposed to. Genomic information is inherited from the parents and forms the basis of the phenotype of an organism. The genetic variation between parents becomes differently distributed between their offspring, leading to trait variation in the offspring. Each trait can be affected by many genes, therefore the genetic architecture can be complex. In complex traits, multiple loci contribute to the ultimate trait value. However, complex traits are shaped not only by genetic variation but also by the environment and the interaction between genotype and environment. The interplay between genetic and environmental variation can affect the fitness of an organism. Chapter 2 discusses how genotype and environment have shaped the phenotype of the nematode Caenorhabditis elegans, the model species used in this thesis, resulting in a laboratory adapted domesticized strain known as Bristol N2. Bristol N2 has been cultivated in the laboratory for over a decade, leading to the fixation of novel mutations in several genes that strongly affect its phenotype. Genotypic variation arisen by novel mutations in the genes npr-1, glb-5, and nath-10 was fixed in N2 due to the laboratory environment. The allelic variation in npr-1 affects the behaviour of this animal in an environment dependent manner, showcasing the interplay between genotype and environment. However, the altered behaviour warrants caution for interpretation of results obtained in the N2 strain. The genotypic effects on trait variation can be large, and one of the more powerful population designs to study these effects are introgression lines. In chapter 3 the construction of a genome-wide introgression line (IL) panel between the N2 and the CB4856 strain is described. This panel contains loci of N2 introgressed in a homogeneous CB4856 background. It is demonstrated that together with CB4856-in-N2 ILs this new genome-wide introgres

Een dodelijk virus bouwde meer dan 400 miljoen jaar geleden een molecuul van het afweersysteem van vissen in zijn genoom, tonen Wageningse celbiologen voor het eerst aan. Daardoor kan dit koiherpesvirus de afweer van karpers en sierkarpers (koi) omzeilen.

Presentatie UDV Onderwijsdag 5 november 2015 over IBR herpesvirus en BVD pestvirus.

African trypanosomosis is a fatal zoonotic disease transmitted by tsetse flies (Diptera; Glossinidae); blood-sucking insects found only in sub-Saharan Africa. Two forms of trypanosomoses occur: the animal African trypanosomosis (AAT; nagana), and the human African trypanosomosis (HAT; sleeping sickness). Since there are no effective vaccines against trypanosomosis, tsetse fly eradication is the most effective disease control method. Tsetse flies can be effectively eradicated by the sterile insect technique (SIT), which is applied in an area-wide integrated pest management approach. SIT is an environmentally benign method with a long and solid record of accomplishments. SIT requires large-scale production of sexually sterilized male flies (by exposure to a precise and specific dose of ionizing radiation, usually from a 60Co or 137Ce source), which are sequentially released into a target wild insect population to out-compete wild type males in inseminating wild virgin females. Once inseminated by sterile males, the virgin females do not produce viable progeny flies. Importantly, these females do not typically re-mate. Ultimately, the target wild insect population can decrease to extinction. However, tsetse SIT programs are faced with a unique problem: laboratory colonies of many tsetse species are infected by the Glossina pallidipes salivary gland hypertrophy virus (GpSGHV; family Hytrosaviridae). GpSGHV-infected flies have male aspermia or oligospermia, underdeveloped female ovarioles, sterility, salivary gland hypertrophy syndrome (SGH), distorted sex ratios, and reduced insemination rates. Without proper management, symptomatic GpSGHV infections (characterized by SGH symptoms) can cause collapse of Glossina colonies. To ensure colony productivity and survival, GpSGHV management strategies are required. This will ensure a sustained supply of sterile males for SIT programs. The aim of this PhD research was to investigate the functional and structural genomics and pro

Insect larvae are orally infected by baculoviruses through ingestion of proteinaceous occlusion bodies (OB) containing the so-called occlusion derived viruses (ODV). OBs disintegrate in the alkaline environment of the insect midgut releasing the ODV, which then bind and fuse with the microvillar membrane of epithelial cells thereby initiating infection. After replication and spread through the larval body, ODVs are assembled and occluded into OBs. In this thesis the protein structure of ODVs and their entry into microvillar cells were studied from the perspective of protein-protein interactions. A number a novel interactions were identified among ODV structural proteins shedding light on the spatial and temporal mechanism of ODV assembly. Furthermore, a group of highly conserved viral per os infectivity factors (PIF) was shown to form a complex on the ODV envelope. These PIF proteins are essential for oral infectivity of ODVs and the complex may play a pivotal role in binding and fusion of ODV with the microvillar membrane. It was further found that in the OB structure a host derived alkaline protease was tightly associated with ODVs and cleaved one of the PIF proteins (P74). Proteolytic processing of PIF proteins may be necessary to trigger conformational changes in the complex to facilitate its function in binding and fusion with the host cell membrane. This thesis provided not only novel insights on the mechanism of ODV entry and assembly and the role of individual ODV proteins, but also triggered new questions to direct future investigations.

Iridoviruses are disease causing agents in (pest) insects, fishes and amphibians with serious ecological and economic impacts. Insight in the composition of the virions and the transcriptional regulation of the virion protein genes is crucial to unravel the biology of this lesser known family of viruses. In this thesis, the virions of Chilo iridescent virus (CIV) (genus Iridovirus) were analyzed by mass spectrometry, revealing 54 virion proteins. A novel transcriptomic approach for non-polyadenylated RNA transcripts, called LACE, was developed and applied to unravel the temporal class of the virion protein genes. This showed that many virion protein genes were expressed as early genes. Another intriguing finding is that an infected cell-specific 100 kDa protein interacted with a crucial delayed-early promoter motif in the DNA polymerase gene and it turned out that this motif was conserved in other (putative) delayed early genes in CIV and other iridoviruses. The hypothesis is that this 100 kDa protein is responsible for transcriptional activation of delayed-early genes. CIV is an example of an invertebrate iridoviruses that deals with induction and inhibition of apoptosis during infection. In this study, a gene for a functional inhibitor of apoptosis (193R), unique for an iridovirus, was identified. In addition, several candidates for pro-apoptotic proteins were found in the virion. In this dissertation fundamental knowledge was obtained on the proteome of CIV virions and the regulation of CIV gene expression. Due to the development and application of novel technics, this thesis provides new venues to answer remaining questions concerning the infection cycle of this interesting iridovirus. Keywords Iridovirus, transcriptomics, proteomics, virus-host interaction

Garnalen missen het immuunsysteem zoals vertebraten dat kennen. Toch zijn garnalen in staat in zekere mate weerstand te bieden aan virussen. Dit werd duidelijk na 'vaccinatie' tegen het 'White Spot Syndrome Virus' (WSSV), de veroorzaker van het 'witte vlekkensyndroom': vaccinatie tegen WSSV bood geen totale bescherming tegen virusinfecties. Een ondernemer die van plan is in de tropen garnalen te kweken, doet er daarom goed aan van meet af aan strikte hygiënemaatregelen in acht te nemen. Immers, WSSV veroorzaakt wereldwijd op garnalenkwekerijen een economische schade van 2-4 miljard US dollar.

Aan de rand van Lelystad vinden we het Centraal Veterinair Instituut. Je komt er niet zomaar binnen, de beveiliging is scherp. Logisch, hier wordt onderzoek gedaan naar de gevreesde aangifteplichtige dierziekten, zoals varkenspest, vogelgriep en mond-en-klauwzeer. Het is onontkoombaar dat daarbij ook weleens met virus wordt gewerkt. Daarom wordt geen enkel risico genomen

De gezondheid van varkenslongen houdt veel varkenshouders en dierenartsen bezig. Dat merken we bij de GD-Veekijker aan de telefoontjes die we dagelijks krijgen. In de top 10 van meest gestelde vragen over ziekteverwekkers stonden in het eerste kwartaal van 2009 vier ziekten die sterk van invloed zijn op longgezondheid. PRRS en het Circovirus staan met afstand op plaats een en twee; Influenza en App staan wat lager in de top 10 van meest gestelde vragen.

Baculoviruses are a large group of enveloped, double-stranded DNA viruses exclusively infectious for arthropods, predominantly insects of the order Lepidoptera. Baculovirology has advanced considerably in recent years as a consequence of the successful use of baculoviruses (i) in biological control of insect pests, (ii) as efficient expression vectors for eukaryotic proteins and (iii) as gene delivery vectors into mammalian cells. In the baculovirus infection cycle two phenotypes of virions, occlusion derived virions (ODVs) and budded virions (BVs), are produced. ODVs start the infection in insect larvae by direct fusion with epithelial cells in the midgut, whereas BVs infect cells from other internal tissues and cells in culture through adsorptive endocytosis. Major envelope fusion proteins located in the apical end of BVs play a major role in these processes as they mediate internalization and fusion for successful penetration of cells.In the family Baculoviridae two distinct envelope fusion proteins are identified in BVs. GP64 is the major envelope fusion protein present in the baculovirus Autographa californica multi capsid nucleopolyhedrovirus (AcMNPV) and other group I nucleopolyhedrovirus BVs. In group II NPVs, for example Spodoptera exigua multi-capsid NPV (SeMNPV), Lymantria dispar MNPV (LdMNPV) and Helicoverpa armigera single-capsid NPV (HearNPV) (Chapter 1), a different type of envelope fusion proteins, designated as F, was present in BVs. Viral F proteins in general mediate low-pH-dependent fusion during virus entry (endocytosis) and baculovirus F proteins are functional analogs of GP64. In spite of significant divergence in primary sequence, baculovirus F proteins are classified as class I fusion proteins based on striking similarity in the architecture and functional elements (signal peptide, proteolytic cleavage site, fusion peptide, heptad repeats and transmembrane region) with fusion proteins of enveloped RNA viruses. To date baculovirus F proteins

White spot syndrome virus (WSSV) is the most important viral pathogen of cultured penaeid shrimp worldwide. Since the initial discovery of the virus inTaiwanin 1992, it has spread to shrimp farming regions in Southeast Asia, theAmericas, Europe and theMiddle Eastcausing major economic losses. The virus has a wide host range among crustaceans and induces distinctive clinical signs (white spots)on the inner surface of the exoskeletonof penaeid shrimps.Limited data is available about the immune response genes of P. monodon upon a WSSV infection. This thesis describes the results of our study into the generation of tools, like the generation of a dedicated microarray enabling the analysis of induction and regulation of (innate) immune defence genes in the host that are activated upon infection. Moreover, a putative vaccination strategy to protect shrimp against lethal WSSV infections has been developed previously. We have also analysed the induction of protective vaccination for induction and regulation of gene expression using this microarray.The first focus had been on the haemocyte response of the shrimp upon an immersion infection (chapter 2). Immunocytochemistry and electron microscopy has been used to study the infection route of WSSV in gills and gut up to 3 days after immersion infection. Using a mouse haemocyte specific monoclonal antibody (WSH8) and a rabbit VP28 polyclonal antibody, double immunoreactivity could be observed. Differential haemocyte characteristics in the gills and the midgut of P. monodon were determined.An invasion of haemocytes in the gills was observed in Penaeus monodon upon WSSV-infection, possibly caused by the adherence of haemocytes to the haemolymph vessels. Although many infected cells were found in the gills, haemocytes were not WSSV-infected in this organ. Gills appear to be an important site of haemocyte invasion after immersion infection. In the midgut, uptake of WSSV in the epithelium could be detected, however, infected nuclei

More than a decade after its discovery inSouth-East Asia, White Spot Syndrome Virus (WSSV) is still the most important (viral) pathogen in the shrimp culture industry. Despite the shift from culturingPenaeusmonodon towards the presumed less susceptibleLitopenaeusvannamei , the use of specific pathogen free shrimp and the development of more advanced shrimp culturing techniques, WSSV continues to scourge shrimp farms. Therefore there is an urgent need for effective intervention strategies. Vaccination is the generally used method to prevent viral infections in vertebrates. The success of this method depends on the immunological memory generated by the adaptive immune system. Unfortunately, shrimps, as any other arthropod, do not have such an adaptive immune system implying that vaccination would never work. However, some phenomenological observations have been made, indicating that there might be an analogous defense system present in shrimp. With this in mind experiments in this thesis are presented to determine if and how shrimp can be protected against WSSV via vaccination.At the start of this research project several studies were available describing various major structural proteins present in the WSSVvirionincluding the majorvirionenvelope proteins VP28 and VP19 andvirionstructural proteins VP26, VP24 and VP15 (see thesis vanHulten, 2001). In this research a number of these proteins were investigated in more detail as potential vaccine candidates. For one of these, the majornucleocapsidprotein VP15, it was determined that it was probably (one of) the DNA-binding protein(s) of WSSV (Chapter 2). Experiments revealed that VP15 binds non-specifically to double-stranded DNA, but has a strong preference tosupercoiledDNA, suggesting a possible role in the packaging of the WSSV genome. Furthermore, VP15 formshomomultimersbut does not interact with any of the other major WSSV structural proteins and unlike other basic DNA-binding proteins VP15 was notphosphorylated.The

The European eel ( Anguillaanguilla L.) is a catadromic fish species with its spawning grounds thousands of kilometers away in the ocean, possibly theSargasso Sea. The objective of this study was to elucidate this oceanic phase of migration for the European eel (Anguillaanguilla L.) in the laboratory.This thesis focuses on several aspects of the life cycle of the European eel:A)   Preparation to migration, B)    Simulated migration,C)   Effect of environmental factors (viruses and PCB's) on the migration,D)   Effect of swimming on maturation.In order to investigate this we simulated the migration of spawners in the laboratory by building 22 large swim tunnels of 127 liter specially developed for long term migration. Therefore the title of this thesis is: 'Simulated migration of European eel' . What matters is how much energy is required for the crossing of the Atlantic Ocean. An eel uses only 58 g fat/kg fish while a salmon uses 300 g fat/kg. The energycost of transportation (COT) are4-6 times lower for eels than for salmonids. The second aims of the investigations were to study environmental factors that may have impact on the migration capacity like viruses and pollutants (PCB's). The third aims of the investigations were to test whether endurance swimming induces sexual maturation and development of the gonads.We can conclude that European eels are very efficient swimmers and that healthy well fed eels are able to reach theSargasso Sealeaving enough reserves for the reproduction. Endurance swimming of eels and the ability to migrate are negatively influenced by infections with viruses like EVEX. Also PCB's which are released from depleted lipid stores after migration may interfere with energy use and metabolism.So, although we have found several habitat factors that may interfere with fitness and endurance swimming such as viruses and toxicants (PCBs) which could be a contributing factor to declinin

White Spot Syndrome Virus (WSSV) is a large enveloped DNA virus that infects shrimp and other crustaceans. The virions are approximately 275 x 120 nm in size and have an ovoid to bacilliform shape and a tail-like appendage at one end. Sequencing revealed that the circular, double stranded (ds) DNA genome of WSSV ranges between 293 and 307 kb in size depending on the WSSV isolate. For a sequenced isolate originating fromThailand(WSSV-TH) 184 putative open reading frames (ORFs) were identified on the genome, most of which are unassigned as they lack homology to known genes in public databases. Based on its unique morphological and genetic features, WSSV has been accommodated in the new virus family Nimaviridae (genus Whispovirus ).WSSV causes serious economic losses in shrimp culture, as 100% cumulative mortalities can be reached within 3-10 days under farming conditions. After its discovery in 1992 in Taiwan WSSV has quickly spread into Southeast-Asia and subsequently to shrimp farming areas all over the world. This thesis aims at obtaining fundamental insights in the genomic structure ("genomics") and transcription regulation ("transcriptomics") of WSSV. This in turn may provide better insight in the molecular basis of WSSV biology and epidemiology, which can be useful in the identification of targets for WSSV intervention strategies.Alignment of the complete genome sequences of the isolates WSSV-TW, WSSV-CN and WSSV-TH, originating from Taiwan, China and Thailand, respectively, revealed that the sequences were very similar (over 99% sequence identity), suggesting that the isolates are variants of the same virus species ( Whispovirus ) and probably evolved recently from a common ancestor (Chapter 2). Two major polymorphic loci were identified, variable region (VR) ORF14/15 and VR ORF23/24, and both appeared to be genomic regions where large deletions occur. Further polymorphisms included loci with variable numbers of tandem repeats (VNTR loci). Next to VR ORF14/15 a

Een reportage van een bedrijf met 640 vermeerderingszeugen en met volledig eigen aanfok. Het bedrijf heeft de A-status. De maatschap Huirne gebruikt nu circa een jaar sperma van beren met een hoge gezondheidsstatus

Since its first discovery in Taiwan in 1992, White spot syndrome virus (WSSV) has caused major economic damage to shrimp culture. The virus has spread rapidly through Asia and reached the Western Hemisphere in 1995 (Texas), where it continued its devastating effect further into Central- and South-America. In cultured shrimp WSSV infection can reach a cumulative mortality of up to 100% within 3 to 10 days.One of the clinical signs of WSSV is the appearance of white spots in the exoskeleton of infected shrimp, hence its name.WSSV has a remarkably broad host range, it not only infects all known shrimp species, but also many other marine and freshwater crustaceans, including crab and crayfish. Therefore, WSSV can be considered a major threat not only to shrimp, but also to other crustaceans around the world.The WSSV virion is a large enveloped particle of about 275 nm in length and 120 nm in width with an ellipsoid to bacilliform shape and a tail-like extension on one end. The nucleocapsid is rod-shaped with a striated appearance and has a size of about 300 nm x 70 nm. Its virion morphology, nuclear localization and morphogenesis are reminiscent of baculoviruses in insects. Therefore, WSSV was originally thought to be a member of the Baculovirida e.At the onset of the research presented in this thesis, only limited molecular information was available for WSSV, hampering its definitive classification as well as profound studies of the viral infection mechanism. As the first step towards unraveling the molecular biology of WSSV, terminal sequencing was performed on constructed genomic libraries of its genome.This led to the identification of genes for the large (rr 1) and small (rr 2) subunit of ribonucleotide reductase, which were present on a 12.3 kb genomic fragment (Chapter 2). Phylogenetic analyses using the RR1 and RR2 proteins indicated that WSSV belongs to the eukaryotic branch of an unrooted parsimonious tree and further showed that WSSV and baculoviruses do not

In dit eerste deel een algemene inleiding over visvirussen

In dit eerste deel een algemene inleiding over visvirussen