Calixte Bayrou

Schmallenberg virus: a new Shamonda/Sathuperi-like virus on the rise in Europe

In the summer-fall of 2011, a nonspecific febrile syndrome characterized by hyperthermia, drop in milk production and watery diarrhea was reported in adult dairy cows from a series of farms located in North-West Europe. Further, in November 2011, an enzootic outbreak of abortion, stillbirth and birth at term of lambs, kids and calves with neurologic signs and/or head, spine or limb malformations emerged throughout several European countries. Both syndromes were associated with the presence in the blood (adults) or in the central nervous system (newborns) of the genome of a new Shamonda-Sathuperi reassortant orthobunyavirus provisionally named Schmallenberg virus after the place where the first positive samples were collected. The clinical, pathological, virological and epidemiological facts that were made publicly available during the first 6 months after the emergence are presented here. Current knowledge of the epidemiology of the phylogenetically closest relatives of the newcomer (Shamonda, Sathuperi, Aino and Akabane viruses) is not exhaustive enough to predict whether the current outbreak of Schmallenberg virus is the prelude to endemicity or to a 2 years long outbreak before the infection burns out when serologically naïve animals are no longer available. In the future, cyclic epizootic reemergences are a possibility too, either synchronized with a global decrease of herd immunity or due to antigenic variants escaping the immunity acquired against their predecessors. The latter hypothesis seems unlikely because of the wide array of biologic constraints acting on the genome of viruses whose life cycle requires transmission by a vector, which represses genetic drift. The remarkable stability of the Shamonda virus genome over the last forty years is reassuring in this regard.

Schmallenberg Virus in Calf Born at Term with Porencephaly, Belgium

To the Editor: From the end of August through the end of October 2011, a clinical syndrome involving adult cattle and the fetuses of pregnant cows emerged in the border area between the Netherlands and North Rhine-Westphalia, Germany (1). The syndrome was characterized by nonspecific clinical signs (fever, decreased milk production), severe diarrhea, and some abortions. A metagenomic analysis was conducted on pooled samples from cattle with acute signs on a farm in the city of Schmallenberg, Germany. The analysis detected nucleotide sequences homologous to arthropod-borne Akabane, Aino, and Shamonda viruses, all belonging to the family Bunyaviridae, genus Orthobunyavirus, and Simbu serogroup (1). Real-time PCR detected the genomic RNA of the new and emerging virus, tentatively designated Schmallenberg virus (SBV), in the blood of adult cattle, abdominal fluid of a stillborn calf, and brains of lambs born with birth defects on dozens of farms in the Netherlands, Germany, and Belgium. No data are yet available to predict how the emerging virus might affect the cattle industry. We report the case of a 1-week old calf with severe central nervous system (CNS) lesions probably caused by in utero infection with the new virus. In Belgium in January 2012, a Belgian Blue multiparous cow gave birth to a 45-kg female calf that was morphologically normal but hypertonic and hyperreflexic. Pregnancy had proceeded uneventfully and lasted 9 months and 4 days. Spontaneous reflexes such as sucking, swallowing, micturition, defecation, and crying were completely preserved, but the calf was unable to stand, and its consciousness alternated from mild to severe depression. It was obviously blind and showed ventrolateral strabismus, but the pupils functioned normally. Muscle tone was permanently increased, as indicated by tetanus-like erection of the ears and by a violent but brief startle response to the slightest acoustic or tactile stimulation (Figure). When the calf was placed upright, loss of conscious proprioception was obvious; it maintained its position only a few seconds before collapsing. Altogether, the clinical signs suggested severe dysfunctions of the cerebral cortex, basal ganglia, and mesencephalon. The calf drank from a bottle twice a day for a week, but then was euthanized for humane reasons (infected decubital ulcers). Figure A 7-day old, female, Schmallenberg virus–positive calf showing severe central nervous system dysfunctions (A–C) and lesions (D–E). A) Spontaneously lying down; B–C) standing with assistance; D–G) porcencephaly, ... At necropsy, the cerebellum, brainstem, and diencephalon appeared normal in shape and volume (Figure). However, the cerebral hemispheres were replaced by 2 thin-walled, fluid-filled cysts with some floating islets and peninsulae corresponding to preserved cortex. There was variable preservation of the cerebrum, total liquefaction of occipital lobes, and irregular preservation of the outer layers of some parts of the temporal and frontal lobes. Altogether, the picture was compatible with severe porencephaly or hydranencephaly. The spine showed no sign of scoliosis, and movement of the limb joints was not restricted (i.e., no arthrogryposis). Samples were removed from the remnants of the cerebrum, diencephalon, and organs (thymus, lung, myocardium, jejunum, ileum, mesenteric lymph node, liver, spleen, kidney, and striated muscle), and 3 independent real-time PCR protocols were conducted to detect genomes of bovine viral diarrhea/mucosal disease virus, bluetongue virus serotype 8, and the novel SBV. Initial retrotranscription of the RNA genomes was followed by quantitative (real-time) PCR. The process was conducted by using our procedures (2) and, for SBV, by following the protocol and using recently developed control reagents as described (1). The SBV genome was detected in only CNS samples (quantification cycle value 28.8); bovine viral diarrhea/mucosal disease virus and BTV-8 genomes were not detected. The new virus genome load was 1.61 × 104 copies per gram of cerebrum sample. Taken together, the above data suggest that, like other Simbu serogroup viruses, the new virus crosses the placenta, contaminates the bovine fetus, infects the fetus’ CNS, and causes necrosis and/or developmental arrest of the cerebral cortex. Unlike the viruses mentioned above (3,4), and provided this case is not an exception, the SBV genome seems to persist in the infected fetus and is detectable after birth by real-time reverse transcription PCR, despite gestation length. Although reliable reagents for detecting seroconversion are temporarily unavailable, the persistence of the new virus in fetal tissue should greatly facilitate the epidemiologic monitoring of the emergence and spread of the new virus. When calves from experimentally infected dams are infected with the closest phylogenetic relative to SBV, Akabane virus, porencephaly develops during gestational days 62–96 (5). If the same is true for the new virus, the above calf was probably infected during June 9–July 13, 2011. Therefore, it is hypothesized that infected arthropods were already circulating in the village of Hamois-in-Condroz (50°24′56′′N, 5°8′7′′E), which is ≈240 km southwest of Schmallenberg (51°8′42′′N, 8°17′18′′E), ≈2 months before the emergence of the clinical syndrome that led to the identification of the new virus.

Schmallenberg Virus in Domestic Cattle, Belgium, 2012

To determine prevalence of antibodies against Schmallenberg virus in adult cows and proportion of infection transmitted to fetuses, we tested serum samples from 519 cow/calf pairs in Belgium in spring 2012. Of cattle within 250 km of location where the virus emerged, ≈91% tested positive for IgG targeting nucleoprotein. Risk for fetal infection was ≈28%.

Natural Intrauterine Infection with Schmallenberg Virus in Malformed Newborn Calves

We surveyed morphologic alterations in calves in Belgium that were naturally infected in utero by Schmallenberg virus (SBV) and born with deformities during January–March 2012. SBV-specific RNA was distributed unevenly in different tissues. Natural intrauterine SBV infection of calves might cause serious damage to the central nervous system and muscles.

Rational development of an attenuated recombinant cyprinid herpesvirus 3 vaccine using prokaryotic mutagenesis and in vivo bioluminescent imaging.

Cyprinid herpesvirus 3 (CyHV-3) is causing severe economic losses worldwide in common and koi carp industries, and a safe and efficacious attenuated vaccine compatible with mass vaccination is needed. We produced single deleted recombinants using prokaryotic mutagenesis. When producing a recombinant lacking open reading frame 134 (ORF134), we unexpectedly obtained a clone with additional deletion of ORF56 and ORF57. This triple deleted recombinant replicated efficiently in vitro and expressed an in vivo safety/efficacy profile compatible with use as an attenuated vaccine. To determine the role of the double ORF56-57 deletion in the phenotype and to improve further the quality of the vaccine candidate, a series of deleted recombinants was produced and tested in vivo. These experiments led to the selection of a double deleted recombinant lacking ORF56 and ORF57 as a vaccine candidate. The safety and efficacy of this strain were studied using an in vivo bioluminescent imaging system (IVIS), qPCR, and histopathological examination, which demonstrated that it enters fish via skin infection similar to the wild type strain. However, compared to the parental wild type strain, the vaccine candidate replicated at lower levels and spread less efficiently to secondary sites of infection. Transmission experiments allowing water contamination with or without additional physical contact between fish demonstrated that the vaccine candidate has a reduced ability to spread from vaccinated fish to naïve sentinel cohabitants. Finally, IVIS analyses demonstrated that the vaccine candidate induces a protective mucosal immune response at the portal of entry. Thus, the present study is the first to report the rational development of a recombinant attenuated vaccine against CyHV-3 for mass vaccination of carp. We also demonstrated the relevance of the CyHV-3 carp model for studying alloherpesvirus transmission and mucosal immunity in teleost skin.

Schmallenberg virus circulation in Belgium in 2012

IN Belgium, the end of 2011 and beginning of 2012 were characterised by numerous reports of births at term of calves with neurological signs or malformations of the head, spine or limbs that were subsequently assigned to the emerging Schmallenberg virus (SBV) (Garigliany and others 2012a). Further, the large-scale cross-sectional serological surveys conducted in cattle during spring 2012 concluded that almost all Belgian cattle had already been in contact with the virus (Garigliany and others 2012b, Meroc and others 2013). As the immunity raised by the cow against close phylogenetic …

Feline panleukopenia virus in cerebral neurons of young and adult cats

BackgroundPerinatal infections with feline panleukopenia virus (FPV) have long been known to be associated with cerebellar hypoplasia in kittens due to productive infection of dividing neuroblasts. FPV, like other parvoviruses, requires dividing cells to replicate which explains the usual tropism of the virus for the digestive tract, lymphoid tissues and bone marrow in older animals.ResultsIn this study, the necropsy and histopathological analyses of a series of 28 cats which died from parvovirus infection in 2013 were performed. Infections were confirmed by real time PCR and immunohistochemistry in several organs. Strikingly, while none of these cats showed cerebellar atrophy or cerebellar positive immunostaining, some of them, including one adult, showed a bright positive immunostaining for viral antigens in cerebral neurons (diencephalon). Furthermore, infected neurons were negative by immunostaining for p27Kip1, a cell cycle regulatory protein, while neighboring, uninfected, neurons were positive, suggesting a possible re-entry of infected neurons into the mitotic cycle. Next-Generation Sequencing and PCR analyses showed that the virus infecting cat brains was FPV and presented a unique substitution in NS1 protein sequence. Given the role played by this protein in the control of cell cycle and apoptosis in other parvoviral species, it is tempting to hypothesize that a cause-to-effect between this NS1 mutation and the capacity of this FPV strain to infect neurons in adult cats might exist.ConclusionsThis study provides the first evidence of infection of cerebral neurons by feline panleukopenia virus in cats, including an adult. A possible re-entry into the cell cycle by infected neurons has been observed. A mutation in the NS1 protein sequence of the FPV strain involved could be related to its unusual cellular tropism. Further research is needed to clarify this point.

A stop-gain in the laminin, alpha 3 gene causes recessive junctional epidermolysis bullosa in Belgian Blue cattle

Four newborn purebred Belgian Blue calves presenting a severe form of epidermolysis bullosa were recently referred to our heredo-surveillance platform. SNP array genotyping followed by autozygosity mapping located the causative gene in a 8.3-Mb interval on bovine chromosome 24. Combining information from (i) whole-genome sequencing of an affected calf, (ii) transcriptomic data from a panel of tissues and (iii) a list of functionally ranked positional candidates pinpointed a private G to A nucleotide substitution in the LAMA3 gene that creates a premature stop codon (p.Arg2609*) in exon 60, truncating 22% of the corresponding protein. The LAMA3 gene encodes the alpha 3 subunit of the heterotrimeric laminin-332, a key constituent of the lamina lucida that is part of the skin basement membrane connecting epidermis and dermis layers. Homozygous loss-of-function mutations in this gene are known to cause severe junctional epidermolysis bullosa in human, mice, horse, sheep and dog. Overall, our data strongly support the causality of the identified gene and mutation.

Bovine lymphotropic herpesvirus detected in Belgium

FIELD veterinarians refer approximately 2200 dead animals per year for postmortem examination to the University of Lieges Faculty of Veterinary Medicine. In March 2013, a seven-year-old Belgian blue cow was referred with a history of depression, anorexia, weight loss and purulent metritis that did not respond to standard antibiotic therapies. Postmortem examination revealed severe emaciation (cachexia), chronic …

Re-emergence of the Schmallenberg virus associated triad hydranencephaly-micromyelia-arthrogryposis in a newborn calf in Belgium, 2016

Schmallenberg virus (SBV) emerged in Germany in 2011, then spread rapidly across Europe, causing an epizootic outbreak of abortion, stillbirth and birth at term of lambs, kids and calves with neurological signs and/or musculoskeletal malformations. SBV-associated disease in newborns disappeared in Belgium in 2013. Here, the authors describe a SBV genomic RNA-positive malformed calf born in May 2016. It reveals the return of SBV circulation during the fall of 2015 in the said area.