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ABSTRACT: Bluetongue virus (BTV) is an arthropod-borne orbivirus that infects sheep, wild ruminants and occasionally cattle. Detection and specific identification of BTV is a multistep process. The first step involves the isolation of the virus from the animal's blood or other tissues, followed by inoculation of embryonating chicken eggs (ECE). After the virus has been amplified in ECE, it is passaged into BHK-21 cell culture for subsequent replication and identification. The virus is then amplified further and identified in microtiter plates by the immunoperoxidase assay using a group specific monoclonal antibody. Finally, the viral isolate is typed by a virus neutralization test.
Journal of Virological Methods 07/2000; 87(1-2):13-23. · 2.01 Impact Factor
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ABSTRACT: Two groups of emus were experimentally inoculated with a low and high pathogenic strain of avian influenza virus (AIV), type A to determine the virus susceptibility, pathogenicity, shedding and seroconversion. Emus were found susceptible to infection with AIV, with virus shedding detectable in tracheal and cloacal swabs between 3 and 10 days post-infection. Only the birds infected with the highly pathogenic viral isolate showed a brief period of mild clinical signs associated with infection. Virus recovered from the infected emus was found to be of similar pathogenicity to that of the virus inoculum. All the birds seroconverted by 10 days post-infection, as determined by haemagglutination inhibition, agar gel immunodiffusion and competitive ELISA assays. This study suggests that emus are similar to wild waterfowl in their response to AIV infection, in that they are susceptible and will replicate and shed the virus, but do not show any marked clinical signs of infection.
Avian Pathology 03/1999; 28(1):13-6. · 1.71 Impact Factor
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ABSTRACT: Newcastle disease (ND) in juvenile double-crested cormorants (Phalacrocorax auritus) occurred several times since 1975, but there are relatively few studies on its pathology and diagnosis. In order to describe the distribution of Newcastle disease virus (NDV) and associated lesions in cormorants with ND and to compare diagnostic methods, 25 cormorants with nervous signs from a ND epizootic in Saskatchewan in 1995 (NDE cormorants) were compared with 18 negative control cormorants. Tissues of these birds were examined by necropsy, histology, virus isolation, immunohistochemistry, serology, and reverse transcriptase-polymerase chain reaction (RT-PCR) methods. The NDE cormorants had a characteristic non-suppurative encephalomyelitis, with a significantly higher prevalence of neuronal necrosis, gliosis, perivascular infiltration with mononuclear cells, and endothelial hypertrophy than control cormorants. These lesions were found more frequently in the cerebellum and brain stem than in other parts of the central nervous system. Immunohistochemically, NDV antigen was limited to neurons, glial and endothelial cells in the central nervous system, and to tubular epithelial cells in the kidney. Newcastle disease virus was isolated with the highest prevalence (4/5) and the highest concentration (10(4.8) ELD50/g) from the kidney. The virus isolates often did not agglutinate erythrocytes in the standard hemagglutination test; the presence of NDV was confirmed by use of an indirect immunoperoxidase assay. By RT-PCR, NDV was detected in kidney and jejunum of a NDE cormorant. There was no significant difference between sensitivity of histology, virus isolation, and serology for detecting ND in NDE cormorants.
Journal of wildlife diseases 02/1999; 35(1):8-23. · 1.08 Impact Factor
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ABSTRACT: Pathogenic Newcastle disease virus (NDV) caused several epidemics of Newcastle disease in double-crested cormorants (Phalacrocorax auritus) in recent years. Eleven 16-week-old cormorants were infected with, or exposed to, pathogenic NDV from one of these epidemics and monitored for 70 days. No birds died, four birds had transient ataxia between 12 and 27 days post-infection (d.p.i.), and one bird had neuronal necrosis and non-suppurative encephalitis characteristic for Newcastle disease. The mean haemagglutina-tion inhibiting antibody titre to NDV peaked at 1:630, 21 d.p.i., and decreased to 1:56 70 d.p.i. Duration of NDV excretion from the cloaca was 15 +/- 6.2 d.p.i., with a maximum of 28 d.p.i. The absence of mortality in these birds may have been due to age-related resistance. The excretion of NDV by cormorants in the absence of mortality or clinical signs of disease suggests that the cormorant population could maintain pathogenic NDV through serial infection of susceptible birds. The greatest risk of NDV transmission from cormorants to poultry probably is during autumn migration, through contact with infected birds, excreta or contaminated water.
Avian Pathology 01/1999; 27(6):541-6. · 1.71 Impact Factor
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ABSTRACT: A Newcastle disease epidemic in double-crested cormorants (Phalacrocorax auritus) occurred in July and August 1995, during a 1994-96 study of a breeding colony of this species on Doré Lake (Saskatchewan, Canada). Clinical signs and mortality were observed from a tunnel-and-blind system, and moribund and freshly dead birds were examined virologically. Yolks from cormorant eggs and sera from cormorants and other birds were tested for hemagglutination inhibiting antibodies to Newcastle disease virus (NDV). Evidence of Newcastle disease was limited to juvenile double-crested cormorants, despite close contact with other birds, including American white pelicans (Pelecanus erythrorhynchos) and gulls (Larus spp.). Clinical signs included limb, head or neck paralysis, head or body tremors, ataxia, and blindness; pathogenic NDV was isolated from affected birds. The mortality rate of juvenile cormorants was 32 to 64%, which was high relative to overall first-year mortality in years without epidemics. Thirty-seven of 63 (59%) cormorant sera collected during the epidemic tested positive for antibodies to NDV. Antibody status of cormorant egg yolks depended on stage of incubation, likely due to changes in the amount of water in the yolks. The departure of juvenile cormorants from their nests at 4 wk of age, resulting in an increased contact rate among individuals, may have been important in triggering the epidemic.
Journal of wildlife diseases 08/1998; 34(3):457-71. · 1.08 Impact Factor
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ABSTRACT: The efficacy of vapor-phase hydrogen peroxide in a pass-through box for the decontamination of equipment and inanimate materials potentially contaminated with exotic animal viruses was evaluated. Tests were conducted with a variety of viral agents, which included representatives of several virus families (Orthomyxoviridae, Reoviridae, Flaviviridae, Paramyxoviridae, Herpesviridae, Picornaviridae, Caliciviridae, and Rhabdoviridae) from both avian and mammalian species, with particular emphasis on animal viruses exotic to Canada. The effects of the gas on a variety of laboratory equipment were also studied. Virus suspensions in cell culture media, egg fluid, or blood were dried onto glass and stainless steel. Virus viability was assessed after exposure to vaporphase hydrogen peroxide for 30 min. For all viruses tested and under all conditions (except one), the decontamination process reduced the virus titer to 0 embryo-lethal doses for the avian viruses (avian influenza and Newcastle disease viruses) or less than 10 tissue culture infective doses for the mammalian viruses (African swine fever, bluetongue, hog cholera, pseudorabies, swine vesicular disease, vesicular exanthema, and vesicular stomatitis viruses). The laboratory equipment exposed to the gas appeared to suffer no adverse effects. Vaporphase hydrogen peroxide decontamination can be recommended as a safe and efficacious way of removing potentially virus-contaminated objects from biocontainment level III laboratories in which exotic animal disease virus agents are handled.
Applied and Environmental Microbiology 11/1997; 63(10):3916-8. · 3.83 Impact Factor
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ABSTRACT: A blind panel was tested in a diagnostic evaluation of a reverse transcription (RT) polymerase chain reaction (PCR) method for detecting hog cholera virus (HCV) from pig tissues. The capability of the RT-PCR test to discriminate between HCV and related pestiviruses, bovine viral diarrhea virus (BVDV), and those viruses causing similar diseases in swine, including African swine fever virus (ASFV) and pseudorabies virus (PRV), was also considered. Nucleic acid extraction involved either kit-based or conventional phenol:chloroform:isoamyl alcohol methods. A single-round PCR assay, using primers that hybridize to the conserved p120 nonstructural gene region, was 82.5% sensitive (n = 17) and 100% specific (n = 18) in the detection of the presence of HCV RNA. However, the sensitivity was increased to 100% following a second PCR test. In all, 4 HCV, 7 BVDV, 2 ASFV, and 1 PRV isolates were studied. Novel nucleic acid sequences were generated for 9 HCV strains. Analysis of a portion of the p120 region using these methods was suitable for HCV isolate characterization.
Journal of veterinary diagnostic investigation: official publication of the American Association of Veterinary Laboratory Diagnosticians, Inc 11/1996; 8(4):414-9. · 1.21 Impact Factor
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ABSTRACT: Seventeen Newcastle disease virus (NDV) isolates obtained from cormorants, turkeys, a pelican, and a gull in Canada and the USA collected in 1975, 1990 and 1992 were analyzed for relatedness by monoclonal antibody profiling. In addition, nucleotide sequence analysis was performed in two areas of the fusion (F) gene for 5 of the isolates. No difference in the antigenicity of these 17 viruses, as determined by monoclonal antibody binding patterns, was seen. The amino acid sequences obtained via nucleotide sequencing at the cleavage site of the F protein showed that all the isolates tested had two pairs of basic amino acids immediately upstream of the cleavage site, and a phenylalanine residue at the N-terminus of the F1 protein, which is consistent with velogenic NDV. The deduced amino acid sequence obtained at the cleavage site of the F protein from 6 of the isolates was virtually identical regardless of the species, year of isolation, or location. However, the 1975 cormorant isolate showed marked differences from the 1990-1992 isolates in the nucleotide and deduced amino acid sequence of the F gene signal region. These data indicate that the 1990 and 1992 outbreaks were caused by the same epizootic virus and further suggest that the population of NDV in these wild birds may be very stable. The belief that the velogenic NDV circulating in cormorants in 1992 was transmitted into the free-ranging turkey flocks located near the cormorants in North Dakota is supported by the present study in which no distinction could be made between the viruses isolated from turkeys or wild birds.
Canadian journal of veterinary research = Revue canadienne de recherche vétérinaire 02/1996; 60(1):50-4. · 0.94 Impact Factor
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ABSTRACT: We previously generated rabbit polyclonal antiidiotypic antibody (anti-Id) to a murine monoclonal antibody (M1875) specific for the bluetongue virus core protein VP7, and demonstrated that this anti-Id (designated RAb2-A) had the characteristics of an internal image anti-Id (Ab2 beta). In this communication, RAb2-A was used to induce immune responses in sheep and the responses were compared to immunization with VP7. The immune sera were tested for the presence of anti-VP7 antibodies and the expression of the Id of M1875. Animals immunized with RAb2-A were able to produce M1875-like antibody responses, i.e., they recognized the same or a similar epitope as M1875 and possessed the M1875 Id, without subsequent exposure to the original antigen. This was demonstrated by showing that antibodies induced by RAb2-A (i) reacted specifically with the immunizing anti-Id, (ii) were capable of binding VP7, (iii) inhibited M1875 from binding to VP7, and (iv) inhibited M1875 from binding to RAb2-A. Animals immunized with purified VP7 produced antibodies that possessed the epitope and idiotope specificity of M1875. No antibody responses to VP7 were detected in control animals immunized with either rabbit anti-Id to the pseudorabies virus glycoprotein gII or BHK-21 cell proteins. We conclude that rabbit anti-Id RAb2-A serologically mimics an M1875-defined VP7 epitope sufficiently to function as a surrogate antigen for inducing anti-bluetongue virus VP7 responses.
Viral Immunology 02/1996; 9(1):35-43. · 1.97 Impact Factor
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ABSTRACT: A competitive enzyme-linked immunosorbent assay (C-ELISA), using a group-specific monoclonal antibody against bluetongue virus (BTV), was applied to detect anti-BTV antibodies in serum samples from two llamas (Llama glama) experimentally infected with BTV serotype 10. Antibodies were detected in both llamas by 1 wk or 2 wk post-infection. Antibodies to BTV increased exponentially during the first 4 wk in both llamas and stabilized at an elevated level during the remaining 5-wk-period of the experiment. We evaluated the C-ELISA for 1,442 field sera from bluetongue-free areas, collected from 398 llamas in New Zealand as well as 451 elk (Cervus elaphus canadensis), 323 bison (Bison bison) and 270 reindeer (Rangifer tarandus tarandus) in Canada. Based on the frequency distribution of the C-ELISA values, we propose that the current negative cut-off value of 50% inhibition established for bovine field sera also can be applied to the sera from these wild ruminants. The C-ELISA values for other wild ruminant field sera collected in bluetongue-free areas of Canada from 98 native caribou (Rangifer tarandus caribou), 32 white-tailed deer (Odocoileus virginianus), 14 moose (Alces alces), and nine musk-oxen (Ovibos maschatus) and 15 yak (Bos grunniens) also were less than 50%, with the exception of three caribou samples. Based on our results, we propose that the C-ELISA be used as a rapid and specific test for serodiagnosis of BTV infection in llamas and possibly other wild ruminants.
Journal of wildlife diseases 08/1995; 31(3):327-30. · 1.08 Impact Factor
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ABSTRACT: Anti-idiotypic antibodies (anti-Id or Ab2) were generated in Balb/c mice against either mouse monoclonal or swine polyclonal antibodies (Ab1) to pseudorabies virus (PRV) antigens by conventional and sequential immunization methods. In the conventional method, one antibody preparation was repeatedly injected into the animals, whereas three anti-PRV antibody preparations were used alternately for the sequential immunization procedure. Anti-Ids were serologically characterized for possession of the Ab2s that detect shared idiotype (IdX) on antibodies to PRV antigens. Only the Ab2s that were generated by the sequential immunization method recognized the IdX present on murine and swine antibodies to PRV. The sequential immunization method described herein was anticipated to be helpful for generating virus specific Ab2s as candidates for serodiagnostic reagents or vaccines.
Journal of Virological Methods 08/1994; 48(2-3):301-13. · 2.01 Impact Factor
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The Canadian veterinary journal. La revue veterinaire canadienne 07/1994; 35(6):379-81. · 1.06 Impact Factor
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ABSTRACT: The suitability of autoclaved tap water for the preparation of ELISA reagents and washing buffer was compared with that of ultrapure water, in a standard indirect ELISA for the detection of antibodies to pseudorabies virus (PRV). The performance of the assay, using autoclaved tap water (AT-ELISA) compared favourably to that of the standard assay, using ultrapure water (UP-ELISA) in detecting anti-PRV antibodies in sequential serum samples from a pig experimentally infected with PRV. While both the UP-ELISA and AT-ELISA proved reliable in detecting anti-PRV antibodies in a coded proficiency serum panel (n = 60), the AT-ELISA detected fewer positive sera than the UP-ELISA in evaluating a limited number (n = 80) of field samples. The results suggest that autoclaved tap water may be substituted for ultrapure water for the preparation of ELISA reagents when or where ultrapure water may not be available.
Journal of Virological Methods 03/1994; 46(2):275-8. · 2.01 Impact Factor
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The Veterinary record 03/1993; 132(7):172. · 1.25 Impact Factor
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ABSTRACT: Eight different laboratory stocks of maedi-visna or caprine arthritis-encephalitis virus were examined for the presence of pestiviruses by a fixed-cell immunoperoxidase assay with polyclonal and monoclonal antibodies. All of the viral stocks examined were found to contain noncytopathic pestivirus contaminants. The panel of monoclonal antibodies could not type the isolates as being more related to bovine virus diarrhea virus or border disease virus. However, the results did indicate that all isolates were not the same, except for two from the same laboratory where the source of pestivirus contamination may have been common.
Canadian journal of veterinary research = Revue canadienne de recherche vétérinaire 11/1992; 56(4):370-2. · 0.94 Impact Factor
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ABSTRACT: An indirect enzyme-linked immunosorbent assay (ELISA), was evaluated for its ability to detect serum antibodies against caprine arthritis-encephalitis virus (CAEV). The ELISA was compared to three other serological immunoassays, agar gel immunodiffusion test (AGIDT), immunoblot assay (IBA), and a fixed-cell immunoperoxidase assay (FCIPA). A total of 511 samples, from 40 farms representing a variety of goat breeds and ages were tested. An estimate of the ELISA sensitivity and specificity was made, relative to combined test results of the three other CAEV serological assays. The degree of agreement of test results among these four assays was evaluated. The number of positives detected by the ELISA, AGIDT, IBA and IPA tests was 193, 154, 204 and 163, respectively. Of the 511 sera tested, 172 were positive to any two or all three of these tests, and were defined as reference positive. A total of 237 samples were negative to all three reference tests, and were defined as reference negative. Relative to these references, the ELISA had a point estimate of 98.3% sensitivity and 97.9% specificity. There was good agreement between the ELISA and the other three assays with a kappa statistic of agreement greater than 0.7 for all three comparisons. The ELISA is therefore considered a suitable assay, with high sensitivity and specificity, for detection of antibodies to CAEV in serum.
Canadian journal of veterinary research = Revue canadienne de recherche vétérinaire 08/1992; 56(3):237-41. · 0.94 Impact Factor
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ABSTRACT: Emu antibody responses to avian influenza virus (AIV) infection were evaluated by the competitive enzyme-linked immunosorbent assay (C-ELISA), agar gel immunodiffusion (AGID) and hemagglutination inhibition (HI) tests. All birds infected with AIV H5N1, H5N3, or H7N7 developed antinucleoprotein (NP) antibodies as early as 7 days postinfection as detected by the C-ELISA. The responses lasted 49 days for the emus receiving H5N3 and at least 56 days for emus receiving the other two viruses. By evaluating 50 emu field serum samples, the C-ELISA was found more sensitive than the AGID test for the detection of anti-NP antibodies. This study indicates that emus experimentally infected with AIV developed antibody responses that can be detected by C-ELISA, AGID, and HI tests. The results from this and our previous studies demonstrate the use of the C-ELISA as a substitute for the AGID test in a routine serodiagnostic screening for detection of antibodies to AIV infection in multiple avian species.
Avian Diseases 42(4):757-61. · 1.46 Impact Factor
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ABSTRACT: A competitive enzyme-linked immunosorbent assay (C-ELISA) employing a baculovirus-expressed recombinant nucleoprotein and a monoclonal antibody was developed for the detection of antibodies to type A influenza virus nucleoprotein. The performance of the C-ELISA was evaluated by testing 756 chickens, 1123 turkeys, 707 emus, and 1261 ostriches, for a total of 3847 serum samples. Relative to the agar gel immunodiffusion (AGID) test, the C-ELISA had a sensitivity of 100% for all four species. The C-ELISA's sensitivity relative to the hemagglutination-inhibition (HI) test results was 100% for chicken, turkey, and emu and 96.2% for the ostrich serum samples. More than 90% of the AGID-negative/C-ELISA-positive serum samples were found positive by HI for at least one influenza serotype. The specificity of C-ELISA relative to AGID ranged from 85.5% to 99.8% for sera collected from these species. These results indicated that the C-ELISA was more sensitive and more specific than the AGID test and as sensitive and as specific as the HI test. The C-ELISA has the potential to replace the AGID test for screening sera from avian species, including ratites, for detection of antibodies to type A influenza virus.
Avian Diseases 42(3):517-22. · 1.46 Impact Factor
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ABSTRACT: The development and evaluation of an enzyme-linked immunosorbent assay (ELISA) for the detection of antibodies to avian pneumovirus (APV) in chicken or turkey sera is described. The assay was capable of detecting serological responses as early as 11 days after chickens had been experimentally exposed to APV. The assay was evaluated by testing 4989 chicken or turkey sera from Canada (a known APV-negative country) and by testing 1190 chicken or turkey sera assumed positive from evidence of other laboratory results or clinical signs. This evaluation indicated that the ELISA was 98.7% sensitive and 99.5% specific. Evaluation of the agreement between the results of this ELISA and that of another laboratory was done by testing a panel of 218 chicken or turkey sera. The Kappa statistic for agreement was 0.92, indicating an excellent level of agreement between the two laboratories.
Avian Diseases 38(4):694-700. · 1.46 Impact Factor
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