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PubMedDate not supplied

The avian response to Newcastle disease virus.

Newcastle disease virus (NDV) is classified as a member of the superfamily Mononegavirales in the family Paramyxoviridae. This virus family is divided into two subfamilies, the Paramyxovirinae and the Pneumovirinae. In 1993 the International Committee on the Taxonomy of Viruses rearranged the order of the Paramyxovirus genus and placed NDV within the Rubulavirus genus among the Paramyxovirinae. The enveloped virus has a negative sense single-stranded RNA genome of 15,186 kb which codes for an RNA directed RNA polymerase, hemagglutinin-neuraminidase protein, fusion protein, matrix protein, phosphoprotein and nucleoprotein in the 5' to 3' direction. The virus has a wide host range with most orders of birds reported to have been infected by NDV. Isolates are characterized by virulence in chickens and are categorized into three main pathotypes depending on severity of disease. Lentogenic isolates are of low virulence while viruses of intermediate virulence are termed mesogenic. Highly virulent viruses that cause high mortality in birds are termed neurotropic or viscerotropic velogenic. Velogenic NDV are List A pathogens that require reporting to the Office of International Epizootics and outbreaks result in strict trade embargoes. The primary molecular determinant for NDV pathogenicity is the fusion protein cleavage site amino acid sequence. Vaccination for NDV is primarily by mass application of live-virus vaccines among commercial poultry. Although protection is measured by presence of antibodies to NDV, vaccinated B-cell depleted chickens are resistant to disease. Consequently, immune protection involves responses that are presently incompletely defined.

Animals↗
PubMed2001

Identification and characterization of a new intron in Borna disease virus.

Borna disease virus (BDV) has a non-segmented, negative-strand (NNS) RNA genome. In contrast to all other known NNS RNA animal viruses, BDV replication and transcription occur in the nucleus of infected cells. Moreover, BDV uses RNA splicing for the regulation of its genome expression. Two introns (I and II), both present in two viral primary transcripts of 2.5 and 7.2 kb, have been reported in BDV. Here, evidence is provided of a new BDV intron, intron III, generated by alternative 3' splice-site choice. Intron III-spliced mRNAs were detected at early times post-infection and found to be present in cells from different types and species. Intron III-spliced mRNAs have coding capability for two new viral proteins with predicted molecular masses of 8.4 and 165 (p165) kDa. p165 is a deleted form of the BDV L polymerase, containing three RGD motifs and a signal peptide signal that could target it into the secretory pathway. These findings underscore the proteomic complexity exhibited by BDV.

Alternative Splicing↗
PubMed1977

Characterization of the protein and nucleic acid of Aleutian disease virus.

Aleutian disease virus (ADV) was extracted and purified from infected mink. Nucleic acid extracted from the virus was examined in an electron microscope. Three different sizes of molecule, with approximate lengths of 1.2, 0.55, and 0.25 micron, were observed. The ratios of the large molecules to the small molecules were similar in all the particles prepared under different conditions. Equilibrium CsCl density gradient centrifugation showed that ADV nucleic acid had a buoyant density of 1.733 g/cm3. In Cs2SO4, ADV had a lower buoyant density than that of double-stranded RNA. These properties and its sensitivity to DNase suggested that ADV contains DNA. Thermal denaturation curves revealed that the DNA of ADV had a single-stranded configuration. Polypeptide analysis of ADV by polyacrylamide gel electrophoresis revealed the presence of four polypepties, with molecular weights of 30,000, 27,000, 20,500, and 14,000. These polypeptides were present in a ratio of 10:3:10:1, respectively. The data suggested that ADV is closely related to the members of the parvovirus groups.

Aleutian Mink Disease↗
PubMedDate not supplied

Serological profiles of commercial broiler breeders and their progeny. 2. Newcastle disease virus.

Newcastle disease virus (NDV) hemagglutination-inhibition (HI) titers were determined for serum samples from eight commercial broiler breeder flocks and their progeny. The chickens sampled had been vaccinated and reared by different producers in different regions of the United States. Breeder flocks had the highest number of NDV-positive HI titers (greater than or equal to 1:10). Eighty percent or more of the samples from six of eight breeder flocks were positive; the geometric mean titers (GMTs) for those six breeder flocks ranged from 19 to 92. Only 3 of 8 broiler flocks had an increased frequency of positive titers and higher GMTs after vaccination. The frequency of positive titers was greater than 80% in only 2 of 8 of the oldest broiler flocks. The number of NDV-negative titers (less than 1:10) increased with age in most broiler flocks, even though all had been vaccinated once or more with live NDV vaccines.

Animals↗
PubMed2005

Novel insights into the regulation of the viral polymerase complex of neurotropic Borna disease virus.

Borna disease virus (BDV) genetic information is encoded in a highly condensed non-segmented RNA genome of negative polarity. Replication and transcription of the genome occurs in the nucleus, enabling the virus to employ the cellular splicing machinery to process primary transcripts and to regulate expression of viral gene products. BDV establishes a non-cytolytic, persistent infection that in animals is mainly restricted to neurons of the central nervous system. Based on these unique properties, BDV represents the prototype member of the virus family Bornaviridae in the order Mononegavirales. Analysis of molecular aspects of BDV replication has long been hampered by the lack of a reverse genetics system. Only recently, artificial BDV minigenomes permitted the reconstitution of the viral polymerase complex, allowing finally the recovery of BDV from cDNA. As in other families of the Mononegavirales, the active polymerase complex of BDV is composed of the polymerase (L), the nucleoprotein (N) and the phosphoprotein (P). In addition, the viral X protein was identified as potent negative regulator of polymerase activity. Protein interaction studies combined with minireplicon assays suggested that P is a central regulatory element of BDV replication that directs the assembly of the polymerase complex. Most intriguingly, BDV obtained from cDNA with variable genomic termini suggests a novel strategy for viral replication-control. BDV seems to restrict its propagation efficacy by defined 5' terminal trimming of genomic and antigenomic RNA molecules. This review will summarize these novel findings and will discuss them in the context of BDV neurotropism and persistence.

Animals↗
PubMed2004

Importance of serine 200 for functional activities of the hemagglutinin-neuraminidase protein of Newcastle Disease Virus.

Newcastle disease virus (NDV) is an avian paramyxovirus with replication competence in human tumor cells and interesting anti-neoplastic and immune stimulatory properties. In order to increase tumor selectivity of replication, we prepared mutants from the avirulent strain Ulster with monocyclic replication cycle and adapted them for multicyclic replication in human melanoma cells. Two mutants (M1 and M2) showed interesting functional differences: while M2 showed T cell co-stimulatory effects in a tumor-specific cytotoxic T lymphocyte (CTL) assay, M1 did not. A distinct difference of these 2 virus mutants appeared also when testing their capacity to induce interferon-alpha and -beta as well as tumor necrosis factor-related apoptosis-inducing ligand (TRAIL) molecules in human monocytes. Sequence analysis of the hemagglutinin-neuraminidase (HN) molecules of the 2 virus mutants showed 7 non-silent mutational differences. Upon cloning of the HN mutant genes into an expression vector and transfection of cells, only HN derived from M2 (HN-M2) was detected at the cell surface by immunostaining with specific antibodies and showed hemadsorption and neuraminidase activity. In order to define which amino acid was responsible for the loss of functional activity of HN derived from M1 (HN-M1), distinct HN mutants were generated via site-directed mutagenesis and tested. Substitution of serine 200 by a proline abrogated HN expression and its hemadsorption and neuraminidase activities. Molecular modeling revealed that proline 200 in HN influences flexibility of a loop near the entrance to the neuraminidase active site, a function that may be crucial for the functions of this viral protein.

Animals↗
PubMed2004

The use of peptide arrays for the characterization of monospecific antibody repertoires from polyclonal sera of psychiatric patients suspected of infection by Borna Disease Virus.

Borna Disease Virus (BDV) is suspected to infect humans and to be associated with psychiatric disorders. To this date, BDV-reactive antibodies provide the only reliable markers to diagnose human BDV infection. Their diagnostic value, however, was recently questioned by the observation that these antibodies recognize BDV antigen with only low avidity, a typical feature of cross-reacting antibodies. This raised the possibility that the human BDV-reactive antibodies were triggered by other pathogens than BDV. The recent establishment of a peptide array-based screening test allowed the further characterization of these antibodies. It revealed the presence of small amounts of BDV-reactive antibodies in crude human sera that specifically recognized various epitopes of three major BDV proteins. Most importantly, the purified epitope-specific antibodies were shown to bind to BDV antigen with high avidity when assayed by conventional immunofluorescence assay (IFA) or by Western blot. These results are compatible with the view that the presence of BDV-reactive antibodies in human sera reflects an infection with BDV, although the poor affinity maturation remains unexplained. Furthermore, it demonstrates that peptide array-based screening tests are a reliable system for identifying monospecific antibodies from human polyclonal sera with high specificity and sensitivity.

Antibodies, Monoclonal↗
PubMed1999

Peripheral and intracerebral T cell immune response in cats naturally infected with Borna disease virus.

Borna disease virus (BDV) is a neurotropic agent with capacity to cause encephalomyelitis in a wide range of animal species, including horses and cats. Recent studies also point to a link between BDV and human neuropsychiatric disorders. The pathogenesis of Borna disease (BD) has been proposed to be immune-mediated, mainly through the effects of cytotoxic T cells. We used flow cytometric analysis in order to characterize the peripheral and intracerebral T cell immune response in cats naturally infected with BDV. Our results show the presence of two different CD8+ cell populations (CD8+low and CD8+high) in the blood, spleen and brain of these cats. In the brain, CD8+low cells predominated over CD8+high cells. Since CD8+low cells have been suggested to represent a non-MHC-restricted T cell population, the recruitment of such cells to the brains of BDV-infected cats could possibly be of importance for the clearance of virus from neurones.

Animals↗
PubMed2006

Endoplasmic reticulum stress and neurodegeneration in rats neonatally infected with borna disease virus.

Borna disease virus infection of neonatal rats results in a characteristic behavioral syndrome and apoptosis of subsets of neurons in the hippocampus and cerebellum (neonatal Borna disease [NBD]). The cellular mechanisms leading to neurodevelopmental damage in NBD have not been fully elucidated. Insights into this model may have general implications for understanding the pathogenesis of virus-associated neurodevelopmental damage. Here we report the presence of endoplasmic reticulum (ER) stress markers and activation of the unfolded protein response in the NBD hippocampus and cerebellum. Specific findings included enhanced PERK-mediated phosphorylation of eif2alpha and concomitant regulation of ATF4 translation; IRE1-mediated splicing of XBP1 mRNA; and cleavage of the ATF6 protein in NBD rat brains. We found evidence for regional and cell type-specific divergence in the expression of ER stress-induced proapoptotic and quality control signals. Our results demonstrate that ER stress induction in death-susceptible Purkinje neurons in NBD is associated with the expression of the proapoptotic molecule CHOP in the absence of compensatory expression of the ER quality control molecules Bip and protein disulfide isomerase. In contrast, ER stress in death-resistant astrocytes is associated with complementary expression of CHOP and ER quality control signals. These results implicate an imbalance between ER stress-mediated apoptosis and survival signaling as a critical determinant of neural cell fate in NBD.

Animals↗
PubMed1991

The resistance of meat chickens vaccinated by aerosol with a live V4 Newcastle disease virus vaccine in the field to challenge with a velogenic Newcastle disease virus.

Meat chickens housed on a commercial broiler farm in Australia were vaccinated once at 10 to 11 days-of-age by aerosol with live V4 Newcastle disease virus (NDV) vaccine. Groups of vaccinated and unvaccinated birds were flown to Malaysia, where they were challenged with a virulent strain of NDV. Survival rates in vaccinated chickens challenged 7, 14, 21 or 31 d after vaccination were 0.47, 0.77, 0.97 and 0.92, respectively. All unvaccinated chickens died due to Newcastle disease (ND) following challenge. Chickens in Australia and Malaysia were bled and the serums tested for haemagglutination-inhibiting (HI) antibody to NDV. Many vaccinated birds with no detectable antibody, and all birds with a log2 titre of 2 or greater, survived challenge. The results showed that this V4 vaccine induced protective immunity in a significant proportion of chickens within 7 d of mass aerosol vaccination. This early immunity occurred in the absence of detectable circulating HI antibody. Non-HI antibody mediated immunity continued to provide protection up to 31 d after vaccination. Almost all vaccinated birds were protected within 3 w of vaccination. It is concluded that the V4 vaccine is efficacious and could be useful during an outbreak of virulent ND in Australia.

Aerosols↗
PubMed1997

Clinical similarities and close genetic relationship of human and animal Borna disease virus.

Borna disease virus (BDV) is the prototype genus of a new family, Bornaviridae, within the order Mononegavirales. BDV naturally infects animals and man. The symptomatology in animals ranges from subclinical infection to rare cases of encephalitis. Asymptomatic infection seemed more frequent than expected, based on antibody data from 100 healthy horses derived from different stables with a history of diseased cases (30-40% carriers). Likewise, phasic episodes of a neurobehavioral syndrome followed by recovery were much more common than fatal neurologic disease. They were paralleled by expression of BDV antigens (N-protein p40, P-protein p24) and RNA transcripts in peripheral blood mononuclear cells, indicating viral activation. Representative longitudinal studies showed that episodes of depressive illness in humans as well as apathetic phases in infected horses were accompanied by antigen expression and followed a similar clinical course. After recovery, BDV antigen disappeared. This temporal congruence, together with the recent isolation of infectious BDV from such patients, points to a contributory role of this virus in human affective disorders. Successful amelioration of BDV-induced neurobehavioral disease in horses with antidepressants applied in psychiatry, supported a common viral pathomechanism, involving reversible disturbances of the neurotransmitter network in the limbic system. Sequences of genetic material amplified from infected animal tissue and human PBMCs revealed a close interspecies relationship and high sequence conservation of the BDV genome. In human BDV isolates, however, single unique mutations were prominent in four genes. This finding supports the hypothesis that despite of high genomic conservation, species-specific genotypes may be definable, provided the sequences are derived from RNA of infectious virus.

Aged↗
PubMed1997

The complete DNA sequence of lymphocystis disease virus.

Lymphocystis disease virus (LCDV) is the causative agent of lymphocystis disease, which has been reported to occur in over 100 different fish species worldwide. LCDV is a member of the family Iridoviridae and the type species of the genus Lymphocystivirus. The virions contain a single linear double-stranded DNA molecule, which is circularly permuted, terminally redundant, and heavily methylated at cytosines in CpG sequences. The complete nucleotide sequence of LCDV-1 (flounder isolate) was determined by automated cycle sequencing and primer walking. The genome of LCDV-1 is 102.653 bp in length and contains 195 open reading frames with coding capacities ranging from 40 to 1199 amino acids. Computer-assisted analyses of the deduced amino acid sequences led to the identification of several putative gene products with significant homologies to entries in protein data banks, such as the two major subunits of the viral DNA-dependent RNA polymerase, DNA polymerase, several protein kinases, two subunits of the ribonucleoside diphosphate reductase, DNA methyltransferase, the viral major capsid protein, insulin-like growth factor, and tumor necrosis factor receptor homolog.

Base Sequence↗
PubMed2002

Chicken anemia virus and infectious bursal disease virus interfere with transcription of chicken IFN-alpha and IFN-gamma mRNA.

Chicken anemia virus (CAV) and infectious bursal disease virus (IBDV) are the two most important viruses that cause immunosuppression in commercial chickens. Because inapparent, subclinical infections by these viruses cause immunosuppression, there is need for assessment of the immune status of chickens. Interference with induction of transcription for chicken interferon-alpha (ChIFN-alpha) and ChIFN-gamma was noted after subclinical infections with either CAV or IBDV. Because the immunosuppressive viruses of chickens may interfere with transcription for ChIFN-alpha and ChIFN-gamma, we propose using this interference to assess the immune status of chickens.

Animals↗