Schmallenberg virus: emergence of an Orthobunyavirus among ruminants in Western Europe

Recently, a novel virus has been identified among ruminants in Western Europe. This virus, the so-called Schmallenberg virus, belongs to the family Bunyaviridae, genus Orthobunyavirus, serogroup Simbu and is closely related to Akabane, Aino and Shamonda virus. In cattle, acute symptoms in the dam and adult animals generally include high fever, milk drop and diarrhea among others. More importantly, infection during gestation may lead to abortion, stillbirth and congenital malformations. As all bunyaviruses, Schmallenberg virus also uses vectors for efficient transmission. Closely related viruses causing similar symptoms, such as Akabane and Akabane-like viruses, are mainly transmitted by Culicoides. It is very likely that Schmallenberg virus is transmitted by similar vectors. This review provides an overview of Bunyaviridae, their epidemiology, symptoms, prevention and control. Special emphasis is put on the Simbu serogroup of the Orthobunyavirus genus pointing out the similarities between them and closely related members

Diverse microbial interactions with the basement membrane barrier

During primary contact with susceptible hosts, microorganisms face an array of barriers that thwart their invasion process. Passage through the basement membrane (BM), a 50-100-nm-thick crucial barrier underlying epithelia and endothelia, is a prerequisite for successful host invasion. Such passage allows pathogens to reach nerve endings or blood vessels in the stroma and to facilitate spread to internal organs. During evolution, several pathogens have developed different mechanisms to cross this dense matrix of sheet-like proteins. To breach the BM, some microorganisms have developed independent mechanisms, others hijack host cells that are able to transverse the BM (e.g. leukocytes and dendritic cells) and oncogenic microorganisms might even trigger metastatic processes in epithelial cells to penetrate the underlying BM

A trypsin-like serine protease is involved in pseudorabies virus invasion through the basement membrane barrier of porcine nasal respiratory mucosa

Several alphaherpesviruses breach the basement membrane during mucosal invasion. In the present study, the role of proteases in this process was examined. The serine protease-specific inhibitor AEBSF inhibited penetration of the basement membrane by the porcine alphaherpesvirus pseudorabies virus (PRV) by 88.1% without affecting lateral spread. Inhibitors of aspartic-, cysteine-, and metalloproteases did not inhibit viral penetration of the basement membrane. Further analysis using the Soybean Type I-S trypsin inhibitor for the serine protease subcategory of trypsin-like serine proteases resulted in a 96.9% reduction in plaque depth underneath the basement membrane. These data reveal a role of a trypsin-like serine protease in PRV penetration of the basement membrane

Comparative analysis of replication characteristics of BoHV-1 subtypes in bovine respiratory and genital mucosa explants: a phylogenetic enlightenment

In general, members of the Alphaherpesvirinae use the epithelium of the upper respiratory and/or genital tract as a preferential site for primary replication. Bovine herpesvirus type 1 (BoHV-1) may replicate at both sites and cause two major clinical entities designated as infectious bovine rhinotracheitis (IBR) and infectious pustular vulvovaginitis/balanoposthitis (IPV/IPB) in cattle. It has been hypothesized that subtype 1.1 invades preferentially the upper respiratory mucosa whereas subtype 1.2 favors replication at the peripheral genital tract. However, some studies are in contrast with this hypothesis. A thorough study of primary replication at both mucosae could elucidate whether or not different BoHV-1 subtypes show differences in mucosa tropism. We established bovine respiratory and genital organ cultures with emphasis on maintenance of tissue morphology and viability during in vitro culture. In a next step, bovine respiratory and genital mucosa explants of the same animals were inoculated with several BoHV-1 subtypes. A quantitative analysis of viral invasion in the mucosa was performed at 0 h, 24 h, 48 h and 72 h post inoculation (pi) by measuring plaque latitude and penetration depth underneath the basement membrane. All BoHV-1 subtypes exhibited a more profound invasion capacity in respiratory tissue compared to that in genital tissue at 24 h pi. However, at 24 h pi plaque latitude was found to be larger in genital tissue compared to respiratory tissue and this for all subtypes. These similar findings among the different subtypes take the edge off the belief of the existence of specific mucosa tropisms of different BoHV-1 subtypes

A beneficiary role for neuraminidase in influenza virus penetration through the respiratory mucus

Swine influenza virus (SIV) has a strong tropism for pig respiratory mucosa, which consists of a mucus layer, epithelium, basement membrane and lamina propria. Sialic acids present on the epithelial surface have long been considered to be determinants of influenza virus tropism. However, mucus which is also rich in sialic acids may serve as the first barrier of selection. It was investigated how influenza virus interacts with the mucus to infect epithelial cells. Two techniques were applied to track SIV H1N1 in porcine mucus. The microscopic diffusion of SIV particles in the mucus was analyzed by single particle tracking (SPT), and the macroscopic penetration of SIV through mucus was studied by a virus in-capsule-mucus penetration system, followed by visualizing the translocation of the virions with time by immunofluorescence staining. Furthermore, the effects of neuraminidase on SIV getting through or binding to the mucus were studied by using zanamivir, a neuraminidase inhibitor (NAI), and Arthrobacter ureafaciens neuraminidase. The distribution of the diffusion coefficient shows that 70% of SIV particles were entrapped, while the rest diffused freely in the mucus. Additionally, SIV penetrated the porcine mucus with time, reaching a depth of 65 mm at 30 min post virus addition, 2 fold of that at 2 min. Both the microscopic diffusion and macroscopic penetration were largely diminished by NAI, while were clearly increased by the effect of exogenous neuraminidase. Moreover, the exogenous neuraminidase sufficiently prevented the binding of SIV to mucus which was reversely enhanced by effect of NAI. These findings clearly show that the neuraminidase helps SIV move through the mucus, which is important for the virus to reach and infect epithelial cells and eventually become shed into the lumen of the respiratory tract

Herpes Simplex Virus Type 1 Penetrates the Basement Membrane in Human Nasal Respiratory Mucosa

Background: Herpes simplex virus infections are highly prevalent in humans. However, the current therapeutics suffer important drawbacks such as limited results in neonates, increasing occurrence of resistance and impeded treatment of stromal infections. Remarkably, interactions of herpesviruses with human mucosa, the locus of infection, remain poorly understood and the underlying mechanisms in stromal infection remain controversial. Methodology/Principal Findings: A human model consisting of nasal respiratory mucosa explants was characterised. Viability and integrity were examined during 96 h of cultivation. HSV1-mucosa interactions were analysed. In particular, we investigated whether HSV1 is able to reach the stroma. Explant viability and integrity remained preserved. HSV1 induced rounding up and loosening of epithelial cells with very few apoptotic and necrotic cells observed. Following 16-24 h of infection, HSV1 penetrated the basement membrane and replicated in the underlying lamina propria. Conclusions/Significance: This human explant model can be used to study virus-mucosa interactions and viral mucosal invasion mechanisms. Using this model, our results provide a novel insight into the HSV1 stromal invasion mechanism and for the first time directly demonstrate that HSV1 can penetrate the basement membrane

Data sharing in neurodegenerative disease research: challenges and learnings from the innovative medicines initiative public-private partnership model

Efficient data sharing is hampered by an array of organizational, ethical, behavioral, and technical challenges, slowing research progress and reducing the utility of data generated by clinical research studies on neurodegenerative diseases. There is a particular need to address differences between public and private sector environments for research and data sharing, which have varying standards, expectations, motivations, and interests. The Neuronet data sharing Working Group was set up to understand the existing barriers to data sharing in public-private partnership projects, and to provide guidance to overcome these barriers, by convening data sharing experts from diverse projects in the IMI neurodegeneration portfolio. In this policy and practice review, we outline the challenges and learnings of the WG, providing the neurodegeneration community with examples of good practices and recommendations on how to overcome obstacles to data sharing. These obstacles span organizational issues linked to the unique structure of cross-sectoral, collaborative research initiatives, to technical issues that affect the storage, structure and annotations of individual datasets. We also identify sociotechnical hurdles, such as academic recognition and reward systems that disincentivise data sharing, and legal challenges linked to heightened perceptions of data privacy risk, compounded by a lack of clear guidance on GDPR compliance mechanisms for public-private research. Focusing on real-world, neuroimaging and digital biomarker data, we highlight particular challenges and learnings for data sharing, such as data management planning, development of ethical codes of conduct, and harmonization of protocols and curation processes. Cross-cutting solutions and enablers include the principles of transparency, standardization and co-design – from open, accessible metadata catalogs that enhance findability of data, to measures that increase visibility and trust in data reuse

Nulla tenaci invia est via : unraveling herpesvirus mucosal invasion in an ex vivo organ culture

Voor herpesvirussen zoals het bovien herpesvirus 1 (BoHV-1) en 4 (BoHV-4) bij runderen en het humaan herpes simplex virus 1 (HSV-1) en 2 (HSV-2) bij mensen dient de mucosa van het ademhalings-stelsel (respiratoir) en/of het voortplantings-stelsel (genitaal) vaak als voorkeursplaats voor vermeerdering. Vervolgens proberen deze virussen diepere weefsels binnen te dringen, ondanks de aanwezigheid van enkele selectieve gastheerbarrières zoals de basaalmembraan (BM) onder epithelia. Om succesvol te zijn in hun invasie moeten pathogenen dus beschikken over een aantal mechanismen om deze barrières te omzeilen. Inzichten in de mucosale invasiemechanismen gebruikt door virussen zijn echter zeer beperkt en het verwerven hiervan vormt dan ook het doel van deze thesis. In een eerste luik werden in vitro mucosa modellen, bestaande uit enerzijds respiratoire mucosale explanten van het rund en anderzijds uit genitale mucosale explanten van het rund en de mens, op punt gezet. Alle ontwikkelde weefsel modellen konden voor minstens 96 uur na opzet in vitro worden aangehouden met nagenoeg geen negatieve effecten op weefselviabiliteit en -morfologie. In een tweede luik werd de kinetiek van virusspreiding nagegaan voor zowel BoHV-1 en BoHV-4 als HSV-1 en HSV-2 in de ontwikkelde modellen voor respectievelijk het rund en de mens. BoHV-1 blijkt zich op een plaquegewijze manier te verspreiden in het respiratoire en genitale epitheel gevolgd door een snelle doorbraak van de BM vanaf 24 uur post-inoculatie (pi). BoHV-4 daarentegen blijkt enkel in staat genitale mucosa te infecteren. In tegenstelling tot BoHV-1, werden er geen BoHV-4 epitheliale plaques geobserveerd op 24 uur pi, deze werden pas vanaf 48 uur pi duidelijk, en meer nog, BoHV-4 epitheliale plaques penetreerden op geen enkel tijdstip de BM. Wel werden er zeldzame individuele geïnfecteerde monocyt/macrofaag cellen (CD172a+) gezien, dit zowel in het epitheel als in de lamina propria. Ook voor HSV-1 en HSV-2 werd een plaquegewijze spreiding geobserveerd in zowel endocervix als ectocervix. Vanaf 48h pi werd gezien dat een aantal plaques doorheen de BM penetreerden, zij het subtiel. Tot slot werd de rol van het virale glycoproteïnen gE/gI complex in de stromale invasie van BoHV-1 onderzocht. Het effect op replicatiekarakteristieken, zoals invasie doorheen de BM, werd zo nagegaan van enerzijds het volledig uitschakelen van de genen coderend voor gE/gI in het virus zelf en van anderzijds het inhiberen van hun functie door het toevoegen van monoklonale antistoffen die specifiek binden aan gE/gI. Daarnaast werd de lokalisatie onderzocht van zowel wildtype viruspartikels als dat van gE/gI gedeleteerde viruspartikels in basale epitheliale cellen. Virussen die gedeleteerd werden voor gE/gI bleken erg gehinderd te zijn in virale replicatie en spreiding, zowel lateraal als in de diepte. Het toedienen van monoklonale antistoffen, specifiek gericht tegen gE/gI resulteerde enkel in een sterk gereduceerde plaquediepte zonder effect op plaquebreedte of virale replicatie. Wild-type virions bevonden zich eerder basaal en soms lateraal in basale epitheliale cellen, daar waar gE/gI gedeleteerde virions zich eerder op niet-basale zijden bevinden en vaak ook verspreid doorheen de ganse cel. Deze data suggereren een belangrijke rol van het gE/gI complex in BoHV-1 stromale invasie