A virus disease of monkeys causing large superficial growths.
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Animals↗
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[Attempts at isolating a precipitating antigen from a cell culture of bovine virus diarrhea-mucosal disease virus].
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Animals↗
Evolution of foot-and-mouth disease virus.
Foot-and-mouth disease virus evolution is strongly influenced by high mutation rates and a quasispecies dynamics. Mutant swarms are subjected to positive selection, negative selection and random drift of genomes. Adaptation is the result of selective amplification of subpopulations of genomes. The extent of adaptation to a given environment is quantified by a relative fitness value. Fitness values depend on the virus and its physical and biological environment. Generally, infections involving large population passages result in fitness gain and population bottlenecks lead to fitness loss. Very different types of mutations tend to accumulate in the foot-and-mouth disease virus (FMDV) genome depending on the virus population size during replication. Quasispecies dynamics predict higher probability of success of antiviral strategies based on multivalent vaccines and combination therapy, and this has been supported by clinical and veterinary practice. Quasispecies suggest also new antiviral strategies based on virus entry into error catastrophe, and such procedures are under investigation. Studies with FMDV have contributed to the understanding of quasispecies dynamics and some of its biological implications.
Amino Acid Sequence↗
A case of human infection with Newcastle disease virus.
A case of Newcastle disease virus infection in a female laboratory technician is reported for the first time in Malaysia. Infection was acquired by droplet infection of the eye while grinding infected chicken in the laboratory. The case was confirmed by isolation of Newcastle disease virus from an eye swab taken from the subject on the first day of clinical signs. A four-fold rise of haemagglutination-inhibition titre was shown when sera on the third day of infection and 15 days later were compared.
Adult↗
Some virus diseases of domestic animals in the Sultanate of Oman.
Little is known of the occurrence of animal virus diseases in the Sultanate of Oman. This paper reports the results of a countrywide survey carried out in 1978 to establish the prevalence of some important viral pathogens of domestic animals with the dual purpose of providing baselines for future investigations and guidelines for those entrusted with disease control. Foot-and-mouth disease virus type O, previously identified in Oman in 1976, was isolated from clinically affected animals. In addition, virus types A and Asia 1 were isolated from unaffected animals. Serological studies indicated that infection with all 3 types had been widespread. The presence of infectious bovine rhinotracheitis was confirmed by virus isolations and sheep and goat pox, long recognised in Oman, was confirmed by the demonstration of pox particles in dried lesion material. In serological studies antibodies were found to the viruses of peste des petits ruminants, bovine herpes mammillitis, bovine virus diarrhoea, parainfluenza 3 and African horse sickness. There were no significant antibody levels to rinderpest in unvaccinated animals and no antibody to equine infectious anaemia or vesicular stomatitis viruses.
Animals↗
Precipitation reactions with Newcastle disease virus.
Acid precipitated and detergent treated Newcastle disease virus (NDV) antigen was prepared and characterised using the agar gel precipitation (AGP) test. The detergent treated NDV antigen was used to screen antibodies to NDV and the results compared with the conventional haemagglutination inhibition (HI) test titres. AGP test could detect NDV antibodies in serum samples when the corresponding HI titres were 1:8 and above. Detergent treatment of Newcastle disease virus greatly reduced its haemagglutinating ability. Simultaneous detection of antibodies to NDV and infectious bursal disease virus in AGP test was attempted and found successful.
Animals↗
Structural and growth characteristics of infectious bursal disease virus.
The infectious bursal disease virus is not enveloped and has a diameter of 60 nm and a density of about 1.32 g/ml. It contains two pieces of single-stranded RNA with molecular weights close to 2 X 10(6). The capsid is made up of four major polypeptides with molecular weights of 110,000, 50,000, 35,000, and 25,000. The virus replicates in chicken embryo fibroblasts rather than in epitheloid cells. After an eclipse period of 4 h, virus production reaches a maximum about 12 h later. The virus has no structural or biological similarities with defined avian reoviruses, and it cannot be classified in one of the established taxonomic groups.
Animals↗
Prefrontal cortex dysfunction in Borna disease virus (BDV)--infected rats.
Viruses have been proposed to play a role in the pathogenesis of schizophrenia; however, the mechanisms by which infection could cause the affective, cognitive, and movement disorders of schizophrenia are not understood. The neurotropic RNA virus, Borna disease (BD) virus, linked to schizophrenia by serologic studies, causes movement and behavior disorders in a wide variety of mammalian and bird hosts. BD rats have hyperactivity and stereotyped behaviors similar to those that follow neurotoxic or electrolytic lesions in frontal cortex or its catecholamine afferents in rats. BD rats have high levels of viral nucleic acid in the prefrontal cortex (PFC), abnormal mesocortical dopamine activity (elevated levels of DOPAC in PFC), yet no alteration in specific binding of D1 or D2 receptor radioligands in PFC. Since frontal lobe dysfunction is frequently reported in schizophrenia, the BD rat model may provide insights into pathogenesis and management of this debilitating psychiatric disease.
3,4-Dihydroxyphenylacetic Acid↗
Role of the bursa of Fabricius in the pathogenicity of inclusion body hepatitis and infectious bursal disease viruses.
Chickens were chemically bursectomized with cyclophosphamide at 3 days old, and studies made of the effects of infection by inclusion body hepatitis virus (IBHV) and infectious bursal disease virus. In another experiment, 3-week-old chickens were infected with infectious bursal disease virus before inoculation with IBHV. Interference with the bursa of Fabricius by cyclophosphamide or by infectious bursal disease virus enhanced the pathogenicity of IBHV. In contrast, cyclophosphamide effects on the bursa protected chickens against infectious bursal disease.
Animals↗
An antiviral mechanism investigated with ribavirin as an RNA virus mutagen for foot-and-mouth disease virus.
To prove whether error catastrophe/lethal mutagenesis is the primary antiviral mechanism of action of ribavirin against foot-and-mouth disease virus (FMDV). Ribavirin passage experiments were performed and supernatants of Rp1 to Rp5 were harvested. Morphological alterations as well as the levels of viral RNAs, proteins, and infectious particles in the BHK-21 cells infected using the supernatants of Rp1 to Rp5 and control were measured by microscope, real-time RT-PCR, western-blotting and plaque assays, respectively. The mutation frequency was measured by sequencing the complete P1- and 3D-encoding region of FMDV after a single round of virus infection from ribavirin-treated or untreated FMDV-infected cells. Ribavirin treatment for FMDV caused dramatically inhibition of multiplication in cell cultures. The levels of viral RNAs, proteins, and infectious particles in the BHK-21 cells infected were more greatly reduced along with the passage from Rp1 to Rp5, moreover, nucleocapsid protein could not be detected and no recovery of infectious virus in the supernatant or detection of intracellular viral RNA was observed at the Rp5-infected cells. A high mutation rate, giving rise to an 8-and 11-fold increase in mutagenesis and resulting in some amino acid substitutions, was found in viral RNA synthesized at a single round of virus infection in the presence of ribavirin of 1000 microM and caused a 99.7% loss in viral infectivity in contrast with parallel untreated control virus. These results suggest that the antiviral molecular mechanism of ribavirin is based on the lethal mutagenesis/error catastrophe, that is, the ribavirin is not merely an antiviral reagent but also an effective mutagen.
Animals↗
Selective virus resistance conferred by expression of Borna disease virus nucleocapsid components.
Persistent viral infections can render host cells resistant to superinfection with closely related viruses by largely uncharacterized mechanisms. We present evidence for superinfection exclusion in brains of Borna disease virus (BDV)-infected rats and in persistently infected Vero cells, and we suggest that acquired resistance to BDV is due to unbalanced intracellular levels of viral nucleocapsid components. We observed that expression of BDV protein P, N, or X rendered human cells resistant to subsequent challenge with BDV but not with other RNA viruses, indicating that incorrect stoichiometry of nucleocapsid components selectively blocked the polymerase activity of incoming viruses. Vero cells containing high levels of an untranslatable BDV-N transcript remained virus susceptible, demonstrating that viral protein rather than RNA mediated resistance. Transient overexpression of BDV-P in persistently infected Vero cells was also remarkably effective against BDV, indicating that the intracellular balance of viral nucleocapsid components could serve as a target for future therapeutic antiviral strategies.
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Molecular biology of Borna disease virus and persistence.
Borna disease virus (BDV) causes central nervous system (CNS) disease that is frequently manifested by behavioral abnormalities. Recent evidence indicates that the natural host range and geographic distribution of BDV is wider than originally thought BDV has been molecularly characterized as a non-segmented, negative single-stranded (NNS) RNA virus. Its genome (ca 8.9 kb), the smallest among known NNS RNA viruses, has an organization similar to that of other members of the order Mononegavirales. BDV has the property, unique among known animal NNS RNA viruses, of a nuclear site for the replication and transcription of its genome. The nucleocytoplasmic transport of BDV macromolecules is an essential component of the life cycle of BDV. An overlap of transcription units and transcriptive signals, overlap of ORFs, transcriptional readthrough and RNA splicing regulate expression of the BDV compact genome. The concurrent use of such diversity of strategies for the regulation of virus gene expression is unique among known NNS RNA viruses. Moreover, BDV appears to have also an unusual assembly process. Based on its unique genetic and biological features, BDV is considered to be the prototypic member of a new virus family, Bornaviridae, within the order Mononegavirales. Therefore, the investigation of the molecular biology of BDV may provide new insights about the biology of mononegaviruses, which include important human pathogens.
Animals↗
Synthetic peptide vaccines: foot-and-mouth disease virus as a model.
Foot-and-mouth disease virus (FMDV) has been one of the pioneering viral systems in the development of synthetic peptides as vaccines. Protection against FMDV infection is associated with the induction of neutralising antibodies. Therefore, attempts have been made to identify peptides capable of eliciting protective humoral responses. Peptides based on a continuous, immunodominant B cell site on the capsid protein VP1 have been shown to confer limited protection in natural hosts. This probably reflects the difficulties in reproducing the immunogenicity of an entire viral particle by using a much simpler synthetic antigen, due to: (i) the polymorphism of the class II MHC; (ii) the adequate presentation to the immune system of the peptides, and (iii) the difficulties of achieving protection against a highly variable RNA virus, which may favour selection of virus antigenic variants. The improvement of FMD peptide vaccines, and the development of in vitro alternatives to in vivo immunogenic assays require further understanding of the immune mechanisms leading to protection against this important animal virus disease.
Animals↗
Comparison of polymerase chain reaction and virus isolation for detection of epizootic hemorrhagic disease virus in clinical samples from naturally infected deer.
We compared our recently reported reverse transcriptase polymerase chain reaction (PCR)-based assay for detection of epizootic hemorrhagic disease virus (EHDV) in clinical samples with different virus isolation (VI) procedures. Thirty-six blood samples and 1 spleen sample from deer were assessed by the EHDV PCR assay and VI in baby hamster kidney (BHK)-21 cells and embryonated chicken eggs (ECE). The EHDV PCR assay detected EHDV RNA from 6 blood samples obtained from deer during 1988-1989 outbreaks of epizootic hemorrhagic disease and from the spleen and blood samples of a deer with clinical hemorrhagic disease in 1992. The 6 blood samples from the 1988-1989 outbreaks and the spleen sample from the 1992 case were VI positive on BHK-21 cell culture. The blood from the same deer with the PCR- and VI-positive spleen was VI negative in BHK-21 cells and ECE. All EHDV isolates were identified as EHDV serotype 2 by a plaque inhibition test. The results of this study indicate that the sensitivity of the previously described EHDV PCR assay is comparable to or greater than that of the VI method in BHK-21 cell culture or ECE. The EHDV PCR assays could provide a superior diagnostic alternative to the current cumbersome and time-consuming VI procedures.
Animals↗
Presumptive diagnostic differentiation of hog cholera virus from bovine viral diarrhea and border disease viruses by using a cDNA nested-amplification approach.
Hog cholera virus (HCV), bovine viral diarrhea virus (BVDV), and border disease virus (BDV) are closely related pestiviruses. BVDV and BDV are found worldwide but seldom cause disease in swine. In contrast, HCV has been successfully eradicated from swine in several nations but poses a potentially devastating threat to them because of its great virulence. Rapid differential diagnosis of HCV from BVDV and BDV infections in swine is vital for detection of the possible reintroduction of HCV into national herds from which it has been eradicated. Nested polymerase chain reactions (PCRs) for each of two pestiviral genomic segments are described. Amplification of the relatively conserved 5' genomic terminus identified 59 of 61 HCV, BVDV, and BDV isolates generically as pestiviruses. Nested amplification of the second region was designed to differentiate HCV from BVDV and BDV by exploiting relatively conserved differences in the nucleotide sequences that encode the major envelope glycoprotein. This second PCR correctly identified 36 of 36 diverse HCV isolates while failing to recognize any of 25 BVDV and BDV isolates. Multiple restriction fragment length analyses confirmed the identities of both external and nested PCR products. The two sets of PCRs may help confirm the generic identity of most pestiviruses and may permit presumptive differential diagnosis of HCV from BVDV and BDV.
Animals↗
Synthesis of the virus-specified tubules of epizootic haemorrhagic disease virus using a baculovirus expression system.
The formation of virus-specific tubules is one of the most characteristic features in the orbivirus infection cycle, yet little is known about their role in virus replication. The tubuli are composed of a major nonstructural protein, NS1. We have investigated the expression of the NS1-encoding gene of epizootic haemorrhagic disease virus serotype 2 (Alberta-strain) by producing a recombinant Autographa californica nuclear polyhedrosis virus (AcNPV). Prior to cloning in the baculovirus transfer vector, pAcYM1 and cotransfection with AcNPV DNA, the NS1 gene was tailored by means of a polymerase chain reaction method to remove G/C tails. The baculovirus recombinant, AcNPV-EHDV2 NS1, expressed large amounts of a 55 K protein which could be purified by sucrose gradient sedimentation as a tubular complex. It appeared that the tubules could break up into 50 nm diameter circular units, which in turn were composed of approximately 16 subunits. The circular units appeared to be hollow and stacked on top of one another (100 units/micron tubule length), giving the tubules a segmented, ladderlike appearance. A large excess of EHDV2-specific tubuli could also be demonstrated in AcNPV-EHDV2 NS1-infected Spodoptera frugiperda cells by electron microscopic examination of thin sections. With pulse-labelling experiments it was shown that, regardless of the level of NS1 expression, the majority of NS1 synthesized in a 30 min period could only be recovered in a particulate form.
Animals↗
[Distribution of Borna disease virus in naturally infected animals with clinical disease].
Borna disease (BD) is a naturally occurring enzootic encephalomyelitis of horses and sheep. The aetiological agent, Borna disease virus (BDV) is an unclassified, neurotropic, negative stranded RNA virus. The study aimed at providing further information on BD of naturally infected animals. Samples obtained from 20 animals (18 horses, 1 donkey, 1 sheep) were investigated by a series of virological and molecular biological tests. The highly sensitive reverse transcription-polymerase chain reaction (RT-PCR) method was used to analyze the tissue distribution of BDV-specific RNA. BDV-specific RNA was detected in bulbus olfactorius, nucleus caudatus, hippocampus and cerebral cortex of all infected animals. BDV-RNA was also present in the spinal cord, eye, nasal mucosa, parotide gland, lung, heart, liver, kidney, bladder and ovaries. In addition, BV-specific RNA was also detected in conjunctival fluid, nasal secretions and saliva of two infected animals. By Western Blot assays the highest amounts of BDV antigens were demonstrated in bulbus olfactorius, nucleus caudatus, hippocampus and cerebral cortex.
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Identification of a strain of infectious bursal disease virus isolated from mosquitoes.
The Becht strain of infectious bursal disease virus was compared with a virus isolated from Aedes vexans mosquitoes and designed 743 virus. The viruses were compared with respect to cell culture host range, cellular changes resulting from viral infections, growth curves, antigenic relationship, and physicochemical characteristics. The viruses are closely comparable in all these properties, and they are considered to be strains of the same virus. In cross comparisons by the enzyme-linked immunosorbent assay, 743 virus and infectious bursal disease virus were found to be antigenically identical, confirming the results of the neutralization test. The 743 virus differs from most strains of infectious bursal disease virus in that it is nonpathogenic for chickens.
Aedes↗