Suchergebnisse

Eine hochansteckende Tierseuche bewegt sich von Osten auf die Europäische Union zu: die Afrikanische Schweinepest. Sie grassierte zuerst in Russland und ist nun in Polen und Litauen angekommen. Neben Hausschweinen sind auch Wildschweine von dieser schweren Virusinfektion betroffen. Einen Impfstoff gibt es derzeit noch nicht. Das staatliche Friedrich-Loeffler-Institut für Tiergesundheit führt daher Studien durch, um die Dynamik der Erkrankung zu verstehen und Risikofaktoren möglichst umfassend auszuschalten.

Anscheinend unaufhaltsam bewegt sich eine gefährliche Tierseuche von Osten auf die Europäische Union (EU) zu. Es handelt sich um die Afrikanische Schweinepest (ASP). Sie grassiert seit 2007 in Russland und ist nun in Weißrussland angekommen. Neben Haus-schweinen sind auch Wildschweine von der Virusinfektion betroffen. Jüngste Ausbrüche waren nicht einmal 100 Kilometer von den Außengrenzen der EU entfernt. Das Friedrich-Loeffler-Institut führt daher Studien durch, um die Dynamik der Erkrankung möglichst umfassend zu verstehen und Risikofaktoren auszuschalten. Eine Einschleppung der ASP in die EU oder nach Deutschland brächte neben den Auswirkungen für die Tiere auch schwere wirtschaftliche Folgen mit sich.

Die Afrikanische Schweinepest (ASP) gehört zu den wichtigsten und komplexesten viralen Erkrankungen des Schweins und unterliegt national und international der Anzeigepflicht. Ausbrüche führen, nicht nur in Exportnationen, zu weitreichenden sozioökonomischen Konsequenzen. Da bislang kein Impfstoff verfügbar ist, erfolgt die Bekämpfung ausschließlich durch strikte veterinärhygienische Maßnahmen. Wichtiger Bestandteil dieser Maßnahmen ist eien möglichst frühe Erkennung der Erkrankung und eine schnelle und verlässliche Labordiagnose. Klinisch ist die Erkrankung nicht von der Klassischen Schweinepest zu unterscheiden. Insbesondere die zurzeit in Russland auftretenden Ausbrüche der ASP erhöhen das Risiko eines Eintrages in die Europäische Union.

Classical swine fever (CSF) is one of the most important viral diseases of domestic pigs (Sus scrofa domesticus) and wild boar (Sus scrofa). For at least 4 decades, several European Union member states were confronted with outbreaks among wild boar and, as it had been shown that infected wild boar populations can be a major cause of primary outbreaks in domestic pigs, strict control measures for both species were implemented. To guarantee early detection and to demonstrate freedom from disease, intensive surveillance is carried out based on a hunting bag sample. In this context, virologic investigations play a major role in the early detection of new introductions and in regions immunized with a conventional vaccine. The required financial resources and personnel for reliable testing are often large, and sufficient sample sizes to detect low virus prevalences are difficult to obtain. We conducted a simulation to model the possible impact of changes in sample size and sampling intervals on the probability of CSF virus detection based on a study area of 65 German hunting grounds. A 5-yr period with 4,652 virologic investigations was considered. Results suggest that low prevalences could not be detected with a justifiable effort. The simulation of increased sample sizes per sampling interval showed only a slightly better performance but would be unrealistic in practice, especially outside the main hunting season. Further studies on other approaches such as targeted or risk-based sampling for virus detection in connection with (marker) antibody surveillance are needed.

Classical swine fever (CSF) is among the most important diseases of domestic pigs and causes great socio-economic losses. Therefore, control of CSF is given high priority within the European Union, including financial support of concerted control actions in candidate and in potential candidate countries. Unfortunately, from some of these countries information on the CSF situation and related data is very limited. This study was undertaken to gather all available information on the domestic pig population and husbandry, and of the CSF situation in domestic pigs and wild boar in South-Eastern European countries that have recently joined or are applying to join the European Union. A characteristic feature of pig production in Eastern Europe is that most of them are in backyard holdings. Although mandatory vaccination is carried out in most of these countries, sporadic CSF outbreaks still occur. Little is still known about the CSF situation in wild boar. In addition, molecular epidemiology of 97 CSF virus isolates available from these countries, from outbreaks that occurred between 1994 and 2007, was performed. Most of the isolates were from Romania and Bulgaria. Genetic typing showed that almost all isolates (with exception of Croatian and of the Macedonian isolates) belonged to genotype 2.3. On the basis of these sequences, and additional sequences from outbreaks in Eastern and Western European countries taken from the database held at the European Union Reference Laboratory (EURL), two clusters could be distinguished within subtype 2.3. They were tentatively named 2.3.1 and 2.3.2. (C) 2010 Elsevier B.V. All rights reserved

The inter-laboratory comparison tests for classical swine fever (CSF) laboratory diagnosis organised by the European Community Reference Laboratory for CSF are regularly performed within European Union Member States. The objective of this study was to evaluate the results of the inter-laboratory comparison tests carried out over the last decade, from 1998 until 2007, by using a statistical approach. A set of five or six lyophilised sera was sent to participants. These included sera containing CSF antibodies, sera containing antibodies against ruminant pestiviruses, sera containing CSF virus and negative sera. This study focused on the results of the diagnostic reference methods for CSF: the neutralisation test for the detection of CSF antibodies (including its interpretation) and virus isolation for the detection of CSF virus. For the detection of CSF antibodies, results were closest to what was expected by the CommunityReference Laboratory when only neutralisation tests were performed. The percentage of correct results decreased as soon as the results of CSF antibody enzyme-linked immunosorbent assay were included or when sera with antibodies to ruminant pestiviruses were added to the panel. The results for the detection of CSF antibodies are still valid today, as no additional method has been introduced recently. Regarding CSF virus detection, CSF virus isolation is well established but on the way to being superseded as the reference test by reverse-transcription polymerase chain reaction.

The pandemic spread of African swine fever virus (ASFV) genotype II (GTII) has led to a global crisis. Since the circulating strains are almost identical, time and money have been mis-invested in whole-genome sequencing the last years. New methods, harmonised protocols for sample selection, sequencing, and bioinformatics are therefore urgently needed.

Whenever an outbreak of classical swine fever has occurred in the European Union (EU), the basic control measures have usually been supplemented by preventive culling. This strategy has led to a great number of culled pigs, which is discussed by general public and politics from both ethical and economic points of view. Emergency vaccination has been deemed to be an alternative control measure for some time now. PCR testing also provides a possible future strategy, since this method would allow a rapid and reliable testing of pigs in the vicinity of an outbreak farm. In this study, a spatial and temporal Monte-Carlo simulation model was used to compare alternative control strategies based upon these two measures ('Emergency Vaccination', 'Test To Slaughter', 'Test To Control' and 'Vaccination in conjunction with Rapid Testing') with the current control strategy. Two regions for investigation wwith different farm densities were used in the model. In a region with a low farm density, the basic EU control measures seemed to be sufficient to control an epidemic. In a region with a high farm density, additional measures would be necessary. 'Emergency Vaccination' in a 3km application zone and 'Traditional Control' reached the same level of infected farms. Both 'Test To Slaughter' and 'Test To Control' combined with preventive culling led to a lower number of infected farms compared to the sole preventive culling strategy. The alternative control measures can reduce the number of culled farms significantly compared to 'Traditional Control'.

Outbreaks of Classical Swine Fever (CSF) in the European Union have caused enormous economical losses. To facilitate the possibility of free trade with pigs and their products, a chimeric live DIVA vaccine CP7_E2alf was developed. Most likely, passive immunity against CSF virus in populations previously vaccinated with C-strain interferes with the efficacy of CP7_E2alf vaccination. To study the interaction with maternal antibodies, the efficacy of CP7_E2alf in piglets from C-strain vaccinated sows was examined. At 5 or at 8 weeks of age, piglets were vaccinated with CP7_E2alf. The vaccinated piglets together with mock-vaccinated littermate controls were challenged 2 weeks post vaccination with highly virulent CSFV Kozlov. The results showed that CP7_E2alf is effective in preventing mortality, severe clinical signs and pathological lesions in piglets vaccinated at 5 or at 8 weeks of age. Interestingly, the antibodies in the mock-vaccinated control piglets partly neutralized the challenge virus. In earlier studies CSFV Koslov has resulted in 100% mortality in naïve piglets, in this study mortality was reduced to 30% in the piglets infected at 7 weeks of age and to 50% in the piglets infected at 10 weeks of age. In the present study optimal time point for vaccination of piglets with passive immunity was found to be 5 weeks of age.

Von den ersten wegweisenden Impfexperimenten durch Edward Jenner 1796 gegen Pocken sowie Louis Pasteur 1885 gegen die Tollwut bis zu gentechnisch veränderten Impfviren der Gegenwart - die Impfung als eine der wirksamsten vorbeugenden Maßnahmen zum Schutz vor Infektionskrankheiten bei Mensch und Tier blickt auf eine lange Erfolgsgeschichte zurück. Heute sind Impfungen aus einer modernen Gesundheitspolitik und Tierseuchenbekämpfung nicht mehr wegzudenken. Derzeit stehen eine Vielzahl von abgeschwächten Lebend- oder inaktivierten Impfstoffen gegen virale und bakterielle Erreger zur Verfügung, die teilweise eine lang anhaltende Immunität gegen die entsprechenden Infektionskrankheiten bewirken. In Deutschland sind zurzeit mehr als 500 bzw. 450 verschiedene Impfstoffe für den human- und veterinärmedizinischen Bereich zugelassen.

Infections with Classical swine fever virus (CSFV) are a major economic threat to pig production. To combat CSF outbreaks and to maintain trade, new marker vaccines were developed that allow differentiation of infected from vaccinated animals (DIVA principle). The chimeric pestivirus CP7_E2alf was shown to be safe and efficacious. Its DIVA strategy is based on the detection of CSFV Erns-specific antibodies that are only developed on infection. However, for the new marker vaccine to be considered a valuable control tool, a validated discriminatory assay is needed. One promising candidate is the already commercially available enzyme-linked immunosorbent assay, PrioCHECK CSFV Erns ELISA (Prionics BV, Lelystad, The Netherlands). Four laboratories of different European Union member states tested 530 serum samples and country-specific field sera from domestic pigs and wild boar. The ELISA displayed a good robustness. However, based on its reproducibility and repeatability, ranges rather than single values for diagnostic sensitivity and specificity were defined. The ELISA displayed a sensitivity of 90–98% with sera from CSFV-infected domestic pigs. A specificity of 89–96% was calculated with sera from domestic pigs vaccinated once with CP7_E2alf. The ELISA detected CSFV infections in vaccinated domestic pigs with a sensitivity of 82–94%. The sensitivity was lower with sera taken ≤21 days post-challenge indicating that the stage of CSFV infection had a considerable influence on testing. Taken together, the PrioCHECK CSFV Erns ELISA can be used for detection of CSFV infections in CP7_E2alf-vaccinated and nonvaccinated domestic pig populations, but should only be applied on a herd basis by testing a defined number of animals.

Classical swine fever (CSF) is one of the most important diseases of pigs. Vaccination in the European Union is limited to emergency situations. Currently, vaccination for the purpose of disease control is carried out in wild boar populations. Wild boar are in most cases vaccinated using an oral bait vaccine based on the live modified vaccine virus C-strain "Riems". A real-time reverse transcription polymerase chain reaction (RT-PCR) protocol for differentiation of C-strain "Riems" vaccine virus from CSF virus (CSFV) field isolates was published previously. In this real-time RT-PCR system differentiation is based on two nucleotide difference one at the 3' end of each of the primer-binding sites in the ERNS encoding genome region. During extensive diagnostic use of this protocol in an outbreak of CSF in wild boar in Germany, some C-strain positive field samples were found to give negative results in the C-strain "Riems" specific real-time RT-PCR, but positive results in a pan-CSFV real-time RT-PCR system. Moreover, sequencing of C-strain "Riems" vaccine batches for intramuscular use revealed differences in the ERNS encoding region. This led to the assumption that mutations in the corresponding primer-binding site of the C-strain specific system had appeared in the field, and possibly also during manufacturing of different vaccine batches. To test this hypothesis and restore sensitivity, a new primer set for detection of the possible C-strain virus quasi species was designed and tested. (C) 2010 Elsevier B.V. All rights reserved

Due to the vast economic consequences of classical swine fever (CSF) outbreaks, emergency vaccination plans are under discussion in European Union Member States. However, animals vaccinated with the conventional C-strain vaccine are subject to trade restrictions. To ease these restrictions, potent marker vaccines are required. One promising candidate is the chimeric pestivirus CP7_E2alf. For emergency vaccination in a CSF outbreak scenario, early onset of immunity is required. Here, the studies performed with a CP7_E2alf virus stock produced under good manufacturing conditions (GMP) are reported. In challenge experiments, CP7_E2alf induced full clinical protection 1 week after intramuscular vaccination, and 2 weeks after oral immunization. Furthermore, even after application of diluted vaccine preparations complete protection could be achieved if challenge infection was carried out 4 weeks after vaccination. In conclusion, GMP-produced CP7_E2alf proved to be a suitable marker vaccine candidate - also for emergency vaccination - both after intramuscular and oral application. (C) 2009 Elsevier Ltd. All rights reserved

Background African swine fever (ASF) is one of the most complex viral diseases affecting both domestic and wild pigs. It is caused by ASF virus (ASFV), the only DNA virus which can be efficiently transmitted by an arthropod vector, soft ticks of the genus Ornithodoros. These ticks can be part of ASFV-transmission cycles, and in Europe, O. erraticus was shown to be responsible for long-term maintenance of ASFV in Spain and Portugal. In 2014, the disease has been reintroduced into the European Union, affecting domestic pigs and, importantly, also the Eurasian wild boar population. In a first attempt to assess the risk of a tick-wild boar transmission cycle in Central Europe that would further complicate eradication of the disease, over 700 pre-existing serum samples from wild boar hunted in four representative German Federal States were investigated for the presence of antibodies directed against salivary antigen of Ornithodoros erraticus ticks using an indirect ELISA format. Results Out of these samples, 16 reacted with moderate to high optical densities that could be indicative of tick bites in sampled wild boar. However, these samples did not show a spatial clustering (they were collected from distant geographical regions) and were of bad quality (hemolysis/impurities). Furthermore, all positive samples came from areas with suboptimal climate for soft ticks. For this reason, false positive reactions are likely. Conclusion In conclusion, the study did not provide stringent evidence for soft tick-wild boar contact in the investigated German Federal States and thus, a relevant involvement in the epidemiology of ASF in German wild boar is unlikely. This fact would facilitate the eradication of ASF in the area, although other complex relations (wild boar biology and interactions with domestic pigs) need to be considered.