Schmallenberg virus outbreak in the Netherlands: routine diagnostics and test results.

At the end of 2011, a new Orthobunyavirus was discovered in Germany and named Schmallenberg virus (SBV). In the Netherlands malformations in new-born ruminants were made notifiable from the 20th of December 2011. After a notification, malformed new-borns were necropsied and brain tissue was sampled for reverse transcription-polymerase chain reaction (RT-PCR).

Seroprevalence of Schmallenberg virus antibodies among dairy cattle, the Netherlands, winter 2011-2012.

Infections with Schmallenberg virus (SBV) are associated with congenital malformations in ruminants. Because reporting of suspected cases only could underestimate the true rate of infection, we conducted a seroprevalence study in the Netherlands to detect past exposure to SBV among dairy cattle. A total of 1,123 serum samples collected from cattle during November 2011-January 2012 were tested for antibodies against SBV by using a virus neutralization test; seroprevalence was 72.

Evaluation of diagnostic tests for the detection of classical swine fever in the field without a gold standard.

Knowledge of the sensitivity of diagnostic tests for infectious diseases under field conditions can be used to design a surveillance program that increases the effectiveness of the control policy. In this study, the sensitivity of tests for the detection of classical swine fever (CSF) virus (CSFV) under field conditions was estimated without knowledge of the true disease status of the animals tested. During the CSF epidemic of 1997-1998 in The Netherlands, tonsil samples from pigs of CSF suspect farms were collected for laboratory diagnosis of CSE These specimens were tested in a fluorescence antibody test (FAT1) for the presence of CSFV antigen.

Duration of the protection of an E2 subunit marker vaccine against classical swine fever after a single vaccination.

The period during which pigs are protected after vaccination is important for the successful usage of a marker vaccine against classical swine fever virus (CSFV) in an eradication programme. In four animal experiments with different vaccination-challenge intervals we determined the duration of protection of an E2 subunit marker vaccine in pigs after a single vaccination. Unvaccinated pigs were included in each group to detect transmission of the challenge virus.

Chimeric (marker) C-strain viruses induce clinical protection against virulent classical swine fever virus (CSFV) and reduce transmission of CSFV between vaccinated pigs.

Two live recombinant vaccines (Flc9 and Flc11) against classical swine fever (CSF) were evaluated for their capacity to reduce transmission of virulent CSF virus (CSFV) among vaccinated pigs. In Flc9 the 5' terminal half of the E2 gene of the C-strain, a CSFV vaccine strain, was exchanged with the homologous gene of the bovine viral diarrhoea virus (BVDV) strain 5250, the E(rns) gene was exchanged likewise in the chimeric Flc11 virus. Both recombinant vaccines induce an antibody response in pigs that can be distinguished from that induced after a wild-type CSFV infection.

Prevention of transplacental transmission of moderate-virulent classical swine fever virus after single or double vaccination with an E2 subunit vaccine.

The use of a vaccine against classical swine fever virus (CSFV) during an outbreak of CSF should lead to a reduction in the horizontal or vertical transmission of CSFV. The reduction of vertical, i.e.

Laboratory experience during the classical swine fever virus epizootic in the Netherlands in 1997-1998.

From February 1997 till May 1998 the national reference laboratory for classical swine fever (CSF) in the Netherlands was confronted with millions of samples taken from pigs during an outbreak of CSF in a pig dense region. In a limited period major logistic problems needed to be solved regarding the processing of samples and information at the laboratory facilities. In total over 2.

[Laboratory findings during the classic swine fever epidemic of 1997-1998].

The results of the laboratory tests carried out by the Institute for Animal Science and Health (ID-Lelystad), the Netherlands, on samples collected during the Classical Swine Fever (CSF) epidemic 1997-1998 are summarized in this article. The relevance of the different laboratory tests and various samples collected on the eradication of CSF during an outbreak is evaluated.

Laboratory decision-making during the classical swine fever epidemic of 1997-1998 in The Netherlands.

The National Reference Laboratory for classical swine fever (CSF) virus in The Netherlands examined more than two million samples for CSF virus or serum antibody during the CSF epizootic of 1997-1998. The immense amount of samples and the prevalence of border disease (BD) virus and bovine viral diarrhoea (BVD) virus infections in Dutch pig herds necessitated the diagnostic efforts of the laboratory to be focused on generating CSF specific test results throughout the eradication campaign. Detection of 82% of the 429 outbreaks was achieved through the combined use of a direct immunofluorescence and peroxidase assay (FAT/IPA) with samples (tonsils) collected from clinically-suspected pigs.

Determination of the onset of the herd-immunity induced by the E2 sub-unit vaccine against classical swine fever virus.

For a recently developed E2 subunit vaccine against classical swine fever (CSF), the reduction in transmission, at different moments after vaccination, was assessed by animal experiments and statistical calculations. Two experiments were performed to estimate the reproduction ratio R. Experiment 1 consisted of three groups and experiment 2 of two groups each of 10 pigs.

Efficacy and stability of a subunit vaccine based on glycoprotein E2 of classical swine fever virus.

The purpose of this study was to determine the efficacy and stability of an E2 subunit vaccine against classical swine fever virus (CSFV). The vaccine, which contains E2 produced in insect cells by a baculovirus expression vector is a potential marker vaccine, as it allows discrimination between infected and vaccinated pigs. Several vaccination-challenge experiments were performed to determine the dose that protects 95% of the vaccinated pigs (PD95), and to determine the stability and efficacy of the vaccine several months after production.

Porcine reproductive and respiratory syndrome: temperature and pH stability of Lelystad virus and its survival in tissue specimens from viraemic pigs.

We investigated the growth of Lelystad virus (LV) in porcine alveolar macrophages, the thermal and pH stability of the virus in cell culture medium, and its survival in tissue specimens from viraemic pigs. Lelystad virus grew to titres of 10(6) TCID50/ml, which were found at 40 h after virus inoculation when the macrophage cultures showed a cytopathic effect of approximately 40%. In culture medium at pH 7.

Antigenic differentiation of pestivirus strains with monoclonal antibodies against hog cholera virus.

Thirty-one bovine viral diarrhoea virus (BVDV) or border disease virus (BDV) strains and 94 hog cholera virus (HCV) strains were grown in cell culture, and characterized by immunostaining with 13 monoclonal antibodies (MAbs) and one polyclonal serum (PAb) against HCV. All 125 strains were recognized by the PAb. None of the BVDV or BDV strains were detected by the 13 MAbs.