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PubMed2001

Wild birds as a possible natural reservoir of Borna disease virus.

The natural reservoir of Borna disease virus (BDV) is unknown. In this paper, we show that mallards (Anas platyrhyncos) and jackdaws (Corvus monedula) can be subclinically infected carriers of this virus. From faecal samples collected at a bird pond, we were able to amplify fragments of the BDV p24 and p40 genes. Following cloning and sequencing, a phylogenetic analysis revealed that these birds carry strains of BDV closely related to but distinct from the reference strains BDV V and He/80. To our knowledge, this is the first confirmed finding of BDV in wild birds.

Animals↗

PubMedDate not supplied

Response of susceptible versus immune chicks to killed, live-modified, and wild infectious bursal disease virus vaccines.

Modified infectious bursal disease virus (IBDV) administered ocularly to either susceptible or passively immune chicks did not induce protection against bursal atrophy by wild IBDV, while intramuscular (IM) or intrabursal (IB) injection protected susceptible chickens. No protection was obtained in passively immune chickens vaccinated IM or IB. Susceptible and passively immune chickens vaccinated with a single dose of killed-virus suspension (KVS) did not become resistant to wild IBDV challenge. A killed-virus multiple emulsion (KVME) induced partial protection (3/5) against challenge 28 days after subcutaneous vaccination of three-day-old susceptible chickens. At 35 and 42 days old, all susceptible chickens were protected by KVME. Protection by passive antibodies was observed in unvaccinated, KVS-, and KVME-vaccinated chickens challenged at 10 and 17 days of age. Protection was only partial in passively immune chickens vaccinated with KVME after passive antibodies were no longer protective to unvaccinated and KVS-vaccinated chicks. Modified IBDV was detected two days post-IB inoculation only in the bursa of Fabricius of susceptible chickens, while wild IBDV was found also in the thymus, spleen, and blood. No evidence of virus was found in immune chickens inoculated IB with modified IBDV. The growth of wild IBDV was limited to the bursa of Fabricius in immune chickens. Furthermore, the intensity of fluorescence, as well as the number of positive bursa cells, was low when compared with fluorescence in the bursa of susceptible chickens infected with wild IBDV.

Animals↗

PubMed1987

The effect of delayed harvesting as well as freezing and thawing on biological properties of Newcastle disease virus.

Delayed harvest of Newcastle disease virus (NDV) from eggs was less infective (as expressed by its lower infectious titer and a higher number of virus particles per EID50) and more resistant to a temperature of 50 degrees C than the early harvest. On the other hand, little or no effect of delayed harvesting was found on neuraminidase, erythrocyte-fusing and immunogenic properties. Moreover, haemolytic activity of NDV was moderately enhanced when its harvesting from de-embryonated egg was delayed. Treatment of a fresh NDV preparation with repeated freezing and thawing cycles also caused a marked reduction in virus infectivity and induction of its haemolytic activity.

Animals↗

PubMed2005

Comparative studies of the capsid precursor polypeptide P1 and the capsid protein VP1 cDNA vectors for DNA vaccination against foot-and-mouth disease virus.

BACKGROUND: Foot-and-mouth disease virus (FMDV) causes a severe livestock disease, and the virus is an interesting target for virology and vaccine studies. MATERIALS AND METHODS: Here we evaluated comparatively three different viral antigen-encoding DNA sequences, delivered via two physical means (i.e., gene gun delivery into skin and electroporation delivery into muscle), for naked DNA-mediated vaccination in a mouse system. RESULTS: Both methods gave similar results, demonstrating commonality of the observed DNA vaccine effects. Immunization with a cDNA vector expressing the major viral antigen (VP1) alone routinely failed to induce the production of anti-VP1 or neutralizing antibodies in test mice. As a second approach, the plasmid L-VP1 that produces a transgenic membrane-anchored VP1 protein elicited a strong antibody response, but all test mice failed in the FMDV challenge experiment. In contrast, for mice immunized with the viral capsid precursor protein (P1) cDNA expression vector, both neutralizing antibodies and 80-100% protection in test mice were detected. CONCLUSIONS: This strategy of using the whole capsid precursor protein P1 cDNA for vaccination, intentionally without the use of virus-specific protease or other encoding genes for safety reasons, may thus be employed as a relevant experimental system for induction or upgrading of effective neutralizing antibody response, and as a convenient surrogate test system for DNA vaccination studies of FMDV and presumably other viral diseases.

Animals↗

PubMed1999

Spatial and temporal analysis of Ross River virus disease patterns at Maroochy Shire, Australia: association between human morbidity and mosquito (Diptera: Culicidae) abundance.

Notifications of Ross River (RR) virus disease in Maroochy Shire were mapped according to the patient's place of residence, and standardized morbidity ratios were calculated for each of 11 census districts, with 4 areas having higher than average overall rates of RR virus disease notification. Temporal analysis of RR virus disease notifications from each of the 11 areas indicated that epidemics of RR virus disease either were widespread, resulting in higher than average numbers of cases from the majority of areas, or limited to only certain areas. Mosquitoes were collected in CO2 light traps, and the numbers analyzed to determine whether there was any association between mosquito abundance and disease incidence. Seasonal light trap indices for the fresh water-breeding Culex annulirostris Skuse and brackish water-breeding Aedes funereus (Theobald) were correlated positively with disease incidence. There was no apparent association between Aedes vigilax (Skuse) or Aedes procax (Skuse) light trap indices and disease incidence. Identification of human subpopulations with higher than average rates of RR virus disease, and the mosquito vectors associated with virus transmission, should provide a framework for the development of focused and therefore more effective control programs.

Aedes↗

PubMed1980

A new structural protein for Newcastle disease virus.

Proteins induced in Newcastle disease virus (NDV)-infected chick embryo fibroblasts (CEF) and proteins incorporated into virions grown in ovo were analysed by modified versions of a two-dimensional polyacrylamide gel electrophoresis system. The following previously described NDV-induced proteins were detected and resolved from host proteins: L (mol. wt. approx. 200K), HN (75K), F0 (66K), F1 (56K), NP (55K) and M (39K). Two additional polypeptides, NAP (nucleocapsid-associated protein, mol. wt. 56K) and a 36K mol. wt. protein were induced in NDV-infected cells. NAP but not 36K was found in purified virions. Radioactive labelling studies with 3H-glucosamine and 32P-orthophosphate demonstrated that neither NAP nor 36K is glycosylated, but that both are phosphorylated. Variation in the isoelectric point and apparent mol. wt. of NAP among different strains was seen and exactly reproduced in both CEF and baby hamster kidney (BHK) cells. The synthesis of NDV-induced proteins including NAP and 36K was unaffected by actinomycin D, whereas the synthesis of host cell proteins was drastically reduced. These data are evidence that NAP and 36K are virus coded. Peptide analysis indicated that NAP, NP and F1 are unrelated polypeptides. The demonstration that NAP is virus coded, together with its phosphorylation and association with the nucleocapsid, suggest that NAP may be the NDV analogue of the P protein of Sendai virus.

Animals↗

PubMed2004

Studies of genetically defined chimeras of a European type A virus and a South African Territories type 2 virus reveal growth determinants for foot-and-mouth disease virus.

The three South African Territories (SAT) types of foot-and-mouth disease virus (FMDV) display great genetic and antigenic diversity, resulting from the independent evolution of these viruses in different geographical localities. For effective control of the disease in such areas, the use of custom-made vaccines is required. To circumvent the tedious process of vaccine strain selection, an alternative in the control process is being investigated. Specifically, it is proposed to replace the antigenic determinants of an infectious genome-length cDNA copy of a good SAT vaccine strain with those of appropriate field strains, producing custom-made FMDV chimeras for use in vaccine production. Here the construction of an infectious genome-length cDNA copy of the SAT2 vaccine strain, ZIM/7/83, is described, created utilizing an exchange-cassette strategy with an existing A(12) genome-length cDNA clone. The virus derived from this cDNA (designated vSAT2) displayed excellent growth properties in cell culture, indicating its potential usefulness in the production of custom-made vaccine strains. Evaluation of the growth of various SAT2/A12 chimeras created during the derivation of SAT2 infectious cDNA suggested incompatibilities between the non-structural proteins of ZIM/7/83 and the 5' UTR of A(12).

Animals↗

PubMedDate not supplied

Identification of seven isolants of infectious bronchitis virus by interference with the B-1 isolant of Newcastle disease virus.

Seven isolants of infectious bronchitis virus (IBV) interfered with the development of hemagglutinins (HA) by the B-1 isolant of Newcaslte disease virus (NDV) in eggs previously inoculated with these IBV isolants. The I50 [defined as the minimum amount of IBV needed to produce, upon inoculation in embryonating chicken eggs (ECE), HA interference in 50% of these ECE reioculated 10 hr later with 10(2,41 EID50 (HA) of the B-1 strain of NDV] was less than 1 EID50. The interference was considered specific for IBV because if could be eliminated by addition of homologous anti-IBV serum. Furthermore, three other common poultry viruses (laryngotracheitis, fowlpox, and CELO viruses) did not interfere with NDV. In view of its sensitivity, specificity, and simplicity of performance, the IBV-NDV interference test appears to have considerable potential as a diagnostic test for IBV under field conditions.

Coronaviridae↗

PubMed1999

Persistent infection with chicken anaemia virus and some effects of highly virulent infectious bursal disease virus infection on its persistency.

Chicken anaemia virus (CAV) infectivity and the effect of highly virulent infectious bursal disease virus (hv IBDV) infection on CAV's infectivity were examined in chickens inoculated with CAV or inoculated dually with CAV and hv IBDV. Five chickens inoculated dually with hv IBDV at 35 days old and then with CAV at 40 days old exhibited no clinical signs of disease, but showed atrophic bursae of Fabricius when necropsied 4 weeks later. Upon examining the chickens at 7 days postinoculation (dpi) with CAV, it was found that hv IBDV infection had inhibited production of virus neutralising (VN) antibody to CAV, and that it was possible to recover CAV from plasma of these chickens. Although VN antibody to CAV appeared after 14 dpi, CAV was recovered from blood cells (BC s) at high titres ranging from 10(2.5)to 10(5.5)TCID(50)/0.1 ml, 7 to 28 dpi in IBDV -induced immunosuppressed chickens. In addition, CAV was sporadically recovered, using rectal swabs, from the dually inoculated chickens at low titers, ranging from 10(1.0)to 10(2. 0)TCID(50)/0.1 ml). In contrast, although CAV was recovered from BC s in most of the chickens inoculated with CAV alone, the titers were lower (10(1.0)to 10(2.5)TCID(50)/0.1 ml). No CAV was detected from the rectal swabs of these chickens. The results of virus recovery were confirmed by polymerase chain reaction. This study first examined the persistency of CAV in BC s and the effective enhancement of primary CAV infection as a result of immunosuppression caused by hv IBDV infection.

Anemia↗

PubMed2004

Cytopathogenicity of classical swine fever viruses that do not show the exaltation of Newcastle disease virus is associated with accumulation of NS3 in serum-free cultured cell lines.

Pestiviruses can be distinguished as two biotypes, cytopathogenic (cp) and noncytopathogenic (noncp), by the morphological changes that they induce during growth in cultured cells. In this study, the cp phenotype of several classical swine fever viruses (CSFV) was evaluated by the detections of the nonstructural proteins NS2-3 and NS3 using immunoprecipitation and Western blotting in different porcine cell lines. Most CSFVs that showed the exaltation of Newcastle disease virus (END) phenomenon (END(+) viruses) did not induce cytopathic effect (CPE) in any cell line, and detections of NS2-3 and NS3 showed a strong signal for NS2-3 in the END(+) virus-infected cells. However, clear CPE was observed in serum-free cultured cells (FS-L3 and CPK-NS) infected with viruses that induce intrinsic interference but did not show the END phenomenon (END(-) viruses), and signal of NS3 was strongly detected than that of NS2-3 in these cells at 72 hr after infection. As the results of the analysis of FS-L3 cells infected with ALD (END(+) virus) and ALD-END(-) virus (END(-) virus) at several incubations, the signal of NS3 detected was strengthened with CPE that become evident progressively. These results suggest that CPE is associated with the accumulation of NS3, which is promoted in serum-free cell lines infected with END(-) viruses. Thus, indicating there is a close relationship between CPE and the quantity of NS3 produced in END(-) CSFV infection.

Animals↗

PubMed1977

Isolation of type A influenza and Newcastle disease viruses from migratory waterfowl in the Mississippi flyway.

Twenty-seven chicken red blood cell agglutinating agents were isolated from 187 tracheal swabbings of apparently healthy migratory mallard ducks (Anas platyrhynchos) in the Mississippi flyway. Twenty-four of the isolants were type A influenza virus; 3 lentogenic Newcastle disease viruses were isolated. Isolations were not made from either 65 giant Canada geese (Branta canadensis) or 60 Franklins' gulls (Larus pipixcan).

Animals↗

PubMed1976

A mucosal disease virus infection of the pregnant ewe as a cause of a border disease-like condition.

An experiment was designed to investigate whether a condition in Australian sheep with clinical and pathological similarites to Border Disease was caused by the infection of the pregnant ewe with a Mucosal Disease virus (MDV). Forty ewes, at 58 to 63 days after mating, were inoculated with material from lambs in which all, some or none of the tissues examined contained MDV. The clinical condition was observed only in lambs born to ewes inoculated with MDV-positive material and then only to ewes in the group which had serological evidence of MDV infection. It is concluded that the Border Disease-like condition in Australian sheep is caused by the infection of the pregnant ewe with a Mucosal Disease virus.

Animals↗

PubMedDate not supplied

Interaction between chicken lymphocytes and Newcastle disease virus.

Different strains of Newcastle disease virus (NDV) were added to chicken lymphocytes and JMV-1 and MSB-1 Marek's-disease-derived tumor cell lines to determine the virus-cell interaction. NDV caused fusion and lysis of the cells, and cells supported the growth and multiplication of NDV.

Animals↗

PubMed2002

Identification of infectious bursal disease virus quasispecies in commercial vaccines and field isolates of this double-stranded RNA virus.

Quasispecies of infectious bursal disease virus (IBDV) vaccine and wild-type strains were identified using real-time RT-PCR at a region of the viral genome known for sequence variability. The LightCycler (Idaho Technology, Inc.) and hybridization probe system (Roche, Molecular Biochemicals) were used. An anchor probe labeled with LightCycler Red 640 and mutation probe labeled with fluorescein were designed using the Del-E IBDV sequence. The sequence of the mutation probe included nucleotides in the hydrophilic B region of VP2 that are important to a viral neutralizing epitope. This Del-E mutation probe was allowed to hybridize to the RT-PCR products following amplification and its temperature of dissociation (T(m)) from each viral template was determined using the LightCycler melting peak analysis. The observed T(m) for the Del-E mutation probe with its homologous virus, Del-E, was usually 65.5 degrees C but ranged from 65 to 66.4 degrees C. Peak melting temperatures for the test viruses were inversely proportional to the number of mutations observed between the Del-E mutation probe and target virus sequence. All the IBDV vaccine strains tested and all but two of the wild-type strains exhibited more than one melting peak, indicating that genetic subpopulations or quasispecies of the viruses were present in the samples. Since the mutation probe was located at a site which encodes a neutralizing epitope of the virus, it is possible that the genetic differences observed are translated into antigenic changes in this VP2 epitope and contribute to antigenic diversity in the quasispecies cloud.

Commerce↗

PubMed1995

Nucleotide sequence analysis of Jembrana disease virus: a bovine lentivirus associated with an acute disease syndrome.

The complete nucleotide sequence of the RNA genome of Jembrana disease virus (JDV), a lentivirus that causes an acute disease syndrome in Bali cattle (Bos javanicus), is reported. In addition to the gag, pol and env genes and flanking long terminal repeats (LTRs) that characterize all retroviruses, a number of accessory genes represented by small multiply spliced ORFs in the central and 3'-terminal regions of the genome, including tat and rev that are typical of lentiviruses, were identified. The genome of JDV was 7732 bp in length, 750 bp smaller than the genome of bovine immunodeficiency virus (BIV) strain BIV127. A striking feature of the genome was the many deletions relative to BIV127, the largest of which were 471 bp from the env gene and 157 bp from the U3 (promoter) region in the LTR. There were also several insertions of up to 33 bp in the JDV genome relative to BIV127 found in the env gene and small ORFs that overlap env. Other significant genomic differences between JDV and BIV127 included changes to cis-acting sequences throughout the genome such as promoter and enhancer sequences in the LTR, the trans-activation response region, splice sites and frameshift sequences; alterations to the gag precursor protein cleavage sites and thus the processed products; loss of the vpw and vpy ORFs; and amino acid changes in all coding regions. The significance of these changes is discussed in relation to the differences in pathogenicity between JDV and BIV.

Acute Disease↗

PubMed2003

Oral immunization using tuber extracts from transgenic potato plants expressing rabbit hemorrhagic disease virus capsid protein.

Rabbit hemorrhagic disease, which is caused by a calicivirus, is a lethal infection of adult animals that is characterized by acute liver damage and disseminated intravascular coagulation. In this study, we report the production of the major structural protein VP60 of rabbit hemorrhagic disease virus in transgenic tubers of potato plants and its use as an oral immunogen in rabbits.

Animals↗

PubMed2005

Short hairpin RNA targeted to the highly conserved 2B nonstructural protein coding region inhibits replication of multiple serotypes of foot-and-mouth disease virus.

Foot-and-mouth disease virus (FMDV) is one of the most contagious agents of animals. Recent disease outbreaks in FMD-free countries have prompted the development of new control strategies that could improve the levels of protection against this virus. We have delivered a plasmid expressing a short hairpin RNA (shRNA) directed against a highly conserved sequence in the 2B nonstructural protein coding region of FMDV RNA to porcine cells. After virus infection, these cells showed a significant reduction in the synthesis of viral RNA and proteins, as well as a decrease in virus yield when compared to control cells. The antiviral effect was sequence specific and not attributable to induction of the interferon pathway. Since FMDV is an antigenically variable virus, we examined the effectiveness of this strategy against multiple serotypes and found that expressed 2B shRNA resulted in efficient silencing of at least 4 FMDV serotypes. Thus, RNA interference may be a potential alternative control strategy to limit the spread of this highly contagious virus in livestock.

Animals↗

PubMed1977

The cerebrospinal fluid of rabbits infected with Borna disease virus.

Rabbits were inoculated intracerebrally with Borna disease virus infected brain suspension or tissue culture extracts. In 30 per cent of the diseased animals infectious virus was present in the cerebrospinal fluid (CSF). The CSF had increased numbers of lymphocytes and an elevation of the protein concentration, mainly due to an increase in gamma-globulins, was measured. The gamma-globulins were of oligoclonal character and reacted with a borna disease virus specific antigen of infected brains or tissue culture cells. The antibody titers in the CSF were of similar level to those in the serum. In comparison, those of the CSF of naturally infected horses always exceeded the serum titers. Injection of tracer substances revealed that no drastic damage to the blood-brain barrier was caused during the disease. The results suggest that antibodies detected in the CSF are locally produced. The significance of these findings for the pathogenesis of Borna disease is discussed.

Albumins↗