Cyclic transmission of Neospora caninum: serological findings in dogs shedding oocysts.

In a previous paper we demonstrated that Hammondia heydorni-like oocysts isolated in 1996 from a naturally infected dog could not be distinguished from the isolate Neospora caninum NC-1. The isolate, designated as H. heydorni-Berlin-1996, was cyclically transmitted using dogs as the final hosts.

Hammondia heydorni-like oocysts shed by a naturally infected dog and Neospora caninum NC-1 cannot be distinguished.

This study describes transmission experiments using Hammondia heydorni-like oocysts isolated in 1996 from a naturally infected dog. The isolate was designated as H. heydorni-Berlin-1996.

Localization of viral proteins in cells infected with bovine viral diarrhoea virus.

Bovine viral diarrhoea virus (BVDV) is a member of the genus Pestivirus within the family Flaviviridae. In this report, protein localization studies were performed to assess the mechanism for the release of mature virus particles from infected cells. Since BVDV is an enveloped virus, budding from either intra- or extracellular membranes is feasible.

Glycoprotein D-independent infectivity of pseudorabies virus results in an alteration of in vivo host range and correlates with mutations in glycoproteins B and H.

Infection of cells by herpesviruses is initiated by the interaction of viral envelope glycoproteins with cellular receptors. In the alphaherpesvirus pseudorabies virus (PrV), the causative agent of Aujeszky's disease in pigs, the essential glycoprotein D (gD) mediates secondary attachment of virions to target cells by binding to newly identified cellular receptors (R. J.

Effect of the pseudorabies virus US3 protein on nuclear membrane localization of the UL34 protein and virus egress from the nucleus.

The alphaherpesvirus UL34 protein is necessary for the primary envelopment of intranuclear capsids at the inner leaflet of the nuclear membrane. In herpes simplex virus type 1, the UL34 protein is exclusively phosphorylated by the protein kinase encoded by the non-essential US3 gene. To investigate the effect of the pseudorabies virus (PrV) US3 product on the intracellular localization of the UL34 protein and on virus morphogenesis, PrV US3 deletion mutants were isolated and characterized.

Classical swine fever (CSF) marker vaccine. Trial II. Challenge study in pregnant sows.

The efficacy of two marker vaccines against classical swine fever (CSF) was tested in a large scale laboratory trial in several National Swine Fever Laboratories (NSFL) of the EU member states. The vaccines were: BAYOVAC CSF Marker (Vaccine A) from Bayer, Leverkusen, Germany and PORCILIS PESTI (Vaccine B) from Intervet, Boxmeer, The Netherlands. At the NSFL of Belgium, The Netherlands and Germany experiments were carried out to examine the ability of the vaccines to prevent transplacental transmission of CSF virus.

Chimeric bovine respiratory syncytial virus with attachment and fusion glycoproteins replaced by bovine parainfluenza virus type 3 hemagglutinin-neuraminidase and fusion proteins.

Chimeric bovine respiratory syncytial viruses (BRSV) expressing glycoproteins of bovine parainfluenza virus type 3 (BPIV-3) instead of BRSV glycoproteins were generated from cDNA. In the BRSV antigenome cDNA, the open reading frames of the major BRSV glycoproteins, attachment protein G and fusion protein F, were replaced individually or together by those of the BPIV-3 hemagglutinin-neuraminidase (HN) and/or fusion (F) glycoproteins. Recombinant virus could not be recovered from cDNA when the BRSV F open reading frame was replaced by the BPIV-3 F open reading frame.

Pseudorabies virus UL37 gene product is involved in secondary envelopment.

Herpesvirus envelopment is a two-step process which includes acquisition of a primary envelope resulting from budding of intranuclear capsids through the inner nuclear membrane. Fusion with the outer leaflet of the nuclear membrane releases nucleocapsids into the cytoplasm, which then gain their final envelope by budding into trans-Golgi vesicles. It has been shown that the UL34 gene product is required for primary envelopment of the alphaherpesvirus pseudorabies virus (PrV) (B.

Cost-efficient vaccination of foxes (Vulpes vulpes) against rabies and the need for a new baiting strategy.

In this study, ecological models, optimisation algorithms and threshold analysis were linked to develop oral-vaccination strategies against rabies in fox populations. It is important that such strategies are cost-efficient and resistant to environmental conditions which would lessen their success. The model validation shows that the ecological models used are suited to predict the proportion of tetracycline- (TC) marked foxes in the course of time.

Immunogenicity of an E1-deleted recombinant human adenovirus against rabies by different routes of administration.

The immunogenic properties of an E1-deleted, human adenovirus type 5 (Ad5) vaccine virus with activity against rabies were examined in mice, foxes and dogs using different routes of administration. NMRI mice received 10(5.8), 10(5.

Oral immunisation against classical swine fever (CSF): onset and duration of immunity.

In an experimental study, onset and duration of immunity after oral immunisation of pigs with a classical swine fever (CSF) live virus vaccine based on the strain "C" has been evaluated. Sixteen weaner piglets (group 1) were orally instilled by syringe with the content of one vaccine bait whereas eighteen piglets (group 2) were fed with one bait. Six unvaccinated piglets represented the control group (group 3).

Identification of different BLV provirus isolates by PCR, RFLPA and DNA sequencing.

A first attempt for the investigation of molecular epidemiology of BLV was carried out. PCR amplicons of a part of the env gene of BLV isolated from 309 cattle of different geographical origin were compared with known BLV env sequences. Using RFLPA most of the PCR products can be assigned to the Australian, the Japanese or the Belgian subgroup.

Protection of chickens from lethal avian influenza A virus infection by live-virus vaccination with infectious laryngotracheitis virus recombinants expressing the hemagglutinin (H5) gene.

The H5 hemagglutinin (HA) gene of a highly pathogenic avian influenza virus (AIV) isolate (A/chicken/Italy/8/98) was cloned and sequenced, and inserted at the non-essential UL50 (dUTPase) gene locus of a virulent strain of infectious laryngotracheitis virus (ILTV). Northern and Western blot analyses of the obtained ILTV recombinants demonstrated stable expression of the HA gene under control of the human cytomegalovirus immediate-early gene promoter. In vitro replication of the HA-expressing ILTV mutants was not affected, and infection of chickens revealed a reduced but still considerable virulence, similar to that of a UL50 gene deletion mutant without foreign gene insertion.

Summary of workshop findings for porcine T-lymphocyte-specific monoclonal antibodies.

Fifty-seven monoclonal antibodies (mAb) selected after the first round analyses in the Third International Swine CD workshop for their possible reactivity with T-lymphocyte specific antigens were further analysed in a second round. As target cells for flow cytometric analyses served peripheral blood mononuclear cells, nylon-wool enriched T-lymphocytes, thymocytes, splenocytes, and lymphocytes derived from Peyer's patches. These second round analyses revealed 15 different data sets.

Deletion of gene 52 encoding glycoprotein M of equine herpesvirus type 1 strain RacH results in increased immunogenicity.

The immunogenicity of equine herpesvirus type 1 (EHV-1) strain RacH was compared to a RacH virus in which gene 52 encoding glycoprotein M (gM) was interrupted by insertion of LacZ (HDeltagM-Ins) and a RacH with 75% of gene 52 was deleted and replaced by LacZ (HDeltagM-HS). HDeltagM-Ins failed to produce full-length gM, but the carboxy-terminal portion was still expressed. No gM expression was detected in HDeltagM-HS-infected cells.

A monoclonal antibody recognising a surface marker on rainbow trout (Oncorhynchus mykiss) monocytes.

The characterisation of a monoclonal antibody (mab 45) reacting with phagocytic leucocytes isolated from blood and spleen of rainbow trout (Oncorhynchus mykiss, Walbaum) is described. The surface marker labelled by this mab is expressed at relative low levels on the membrane of large, nearly nongranulated trout leucocytes, and having the typical morphology of monocytes in flow cytometry (Kfoury et al., 1999, Fish Pathology, 34, 1-6).

Serological evidence for naturally occurring transmission of Neospora caninum among foxes (Vulpes vulpes).

The study describes the time course of the Neospora caninum-specific antibody response in experimentally infected foxes, in naturally N. caninum-seropositive vixens and their litters. An immunofluorescence test, a tachyzoite surface antigen based ELISA and an immunoblot assay were established for this purpose.

Egress of alphaherpesviruses: comparative ultrastructural study.

Egress of four important alphaherpesviruses, equine herpesvirus 1 (EHV-1), herpes simplex virus type 1 (HSV-1), infectious laryngotracheitis virus (ILTV), and pseudorabies virus (PrV), was investigated by electron microscopy of infected cell lines of different origins. In all virus-cell systems analyzed, similar observations were made concerning the different stages of virion morphogenesis. After intranuclear assembly, nucleocapsids bud at the inner leaflet of the nuclear membrane, resulting in enveloped particles in the perinuclear space that contain a sharply bordered rim of tegument and a smooth envelope surface.

Expression of VP5 of infectious pancreatic necrosis virus strain VR299 is initiated at the second in-frame start codon.

Infectious pancreatic necrosis virus (IPNV), a member of the BIRNAVIRIDAE: with two double-stranded RNA genome segments, encodes five proteins designated VP1 to VP5. To study the function of the 17 kDa nonstructural protein VP5 during virus replication several mutated IPNV genome segments A were constructed and included in a reverse genetics system for IPNV to obtain recombinant virus. Mutations between nt 68 and 85 or nt 94 and 103 in the noncoding region failed to yield viable virus.

ELISA and direct immunofluorescence test to detect equine arteritis virus (EAV) using a monoclonal antibody directed to the EAV-N protein.

A monoclonal antibody (mAb) directed against the equine arteritis virus (EAV) nucleocapsid (N) protein was used for indirect enzyme-linked immunosorbent assays (ELISAs) using viral antigen from different sources. The same mAb was labelled with fluorescein isothiocyanate for direct immunofluorescence tests (DIFTs). The N-specific mAb appeared to be suitable for the detection in both ELISA and DIFT of different EAV strains and field isolates from semen and tissue samples after passage in lines of RK-13, Vero and fetal equine kidney cells.

Detection of cattle-derived BSE prions using transgenic mice overexpressing bovine PrP(C).

In interspecies transmissions of transmissible spongiform encephalopathies, the agent has to overcome a species barrier that is largely influenced by the rate of homology between the prion proteins (PrP(C)) of the two involved species. Generating transgenic mice expressing PrP(C) of a foreign species is an approach to develop TSE models that are at least partly devoid of a species barrier. The availability of such animals would enable the detection of low doses of infectivity in tissues or bodily fluids derived from other species.

Characterization of BSE and scrapie strains/isolates.

Following the BSE epidemic in cattle and the emergence of a variant form of Creutzfeldt-Jakob disease in humans, the question was raised whether BSE has been transmitted to small ruminants by the inadvertent feeding of infectious meat and bone meal. Such infections could easily be concealed in countries where scrapie is endemic. To address this issue by immuno-chemically analyzing the PrP(Sc) fragments, we have developed two lines of research.

Experimental infection of European wild boars and domestic pigs with pseudorabies viruses with differing virulence.

Objective: To determine susceptibility of European wild boars (Sus scrofa) to infection with pseudorabies virus (PrV) and to characterize the virulence of a wildboar PrV isolate for wild and domestic pigs.

Animals: 18 wild boars and 16 domestic pigs.

Procedure: Three groups of 4 wild boars were inoculated with PrV Bartha, Kaplan, and a wild-boar isolate (BFW1) and housed with uninfected pigs.

Recombinant bovine respiratory syncytial virus with deletions of the G or SH genes: G and F proteins bind heparin.

Bovine respiratory syncytial virus (BRSV) encodes three transmembrane envelope glycoproteins, namely the small hydrophobic (SH) protein, the attachment glycoprotein (G) and the fusion glycoprotein (F). The BRSV reverse genetics system has been used to generate viable recombinant BRSV lacking either the G gene or the SH gene or both genes. The deletion mutants were fully competent for multicycle growth in cell culture, proving that, of the BRSV glycoprotein genes, the SH and G genes are non-essential.

Role of the cytoplasmic tail of pseudorabies virus glycoprotein E in virion formation.

Glycoproteins M (gM), E (gE), and I (gI) of pseudorabies virus (PrV) are required for efficient formation of mature virions. The simultaneous absence of gM and the gE/gI complex results in severe deficiencies in virion morphogenesis and cell-to-cell spread, leading to drastically decreased virus titers and a small-plaque phenotype (A. Brack, J.