Showing papers on "Newcastle disease published in 2001"
TL;DR: The rescued virus induces a strong humoral antibody response against influenza virus and provides complete protection against a lethal dose of influenza virus challenge in mice, demonstrating the potential of recombinant NDV as a vaccine vector.
Abstract: A complete cDNA clone of the Newcastle disease virus (NDV) vaccine strain Hitchner B1 was constructed, and infectious recombinant virus expressing an influenza virus hemagglutinin was generated by reverse genetics. The rescued virus induces a strong humoral antibody response against influenza virus and provides complete protection against a lethal dose of influenza virus challenge in mice, demonstrating the potential of recombinant NDV as a vaccine vector.
279 citations
TL;DR: Panels of monoclonal antibodies were a major advance for the characterization of NDV isolates, although confirmation of virulence for poultry still required in vivo testing and molecular-based techniques become easier and more reliable.
Abstract: Substantial variation in the virulence of Newcastle disease virus (NDV) isolates means that the detection of NDV or evidence of infection is insufficient for an adequate diagnosis, as control measures for avirulent viruses are very different to those for virulent viruses. Diagnosis therefore requires further characterization, at least as to whether an isolate is virulent or avirulent. Conventional detection and differentiation of ND viruses is perceived as slow, laborious and requiring an undesirable use of in vivo techniques. In addition, further characterization is needed to give greater information on origin and spread. This review concentrates on the application of monoclonal antibody and molecular biological approaches. Panels of monoclonal antibodies were a major advance for the characterization of NDV isolates, although confirmation of virulence for poultry still required in vivo testing. As molecular-based techniques become easier and more reliable, they are likely to supersede the use of monoclonal antibodies, especially for characterizing viruses for epidemiological purposes. The attraction of molecular-based techniques is that they may be able to cover all three aspects of Newcastle disease diagnosis (detection of virus, characterization, including inference of virulence, and epidemiology) quickly, accurately and definitively in a single test. A number of approaches based on the reverse transcriptase polymerase chain reaction have been developed, with subsequent analysis of the product by restriction enzyme analysis, probe hybridization and nucleotide sequencing. Although extensive variation among NDVs still poses technical problems, the real and potential advantages of a molecular biological approach to Newcastle disease diagnosis appear to be overwhelming.
250 citations
TL;DR: Historical and contemporary aspects of Newcastle disease (ND) are reviewed, with particular reference to the greater understanding which modern techniques have allowed, and attempts to control and eradicate ND are not as straightforward as it may appear.
Abstract: 1. In this paper several historical and contemporary aspects of Newcastle disease (ND) are reviewed, with particular reference to the greater understanding which modern techniques have allowed. 2. Virulent ND viruses were generally thought to have emerged in 1926 as a result of transfer from a wild bird host reservoir but there is evidence that the virulent virus may have existed in poultry before 1926. Recent findings suggest that the virulent virus may emerge in poultry as a result of mutations in viruses of low virulence. 3. The history of ND in Great Britain reflects the four known panzootics that have occurred and serves as a model for the impact this disease may have on poultry populations. 4. Attempts to control and eradicate ND are not as straightforward as it may appear; in particular vaccination, while preventing deaths and disease, on challenge may not prevent virus replication and could therefore lead to the virulent virus becoming endemic. 5. Village chickens are extremely important assets in most developing countries, representing a significant source of protein in the form of eggs and meat but endemic ND can cause mortality of up to 60% in village chickens.
231 citations
TL;DR: NDV-P1 showed markedly attenuated pathogenicity for SPF chicken embryos, unlike currently available ND vaccine strains, indicating that the V protein of NDV has a dual function, playing a direct role in virus replication as well as serving as a virulence factor.
Abstract: Newcastle disease virus (NDV) edits its P-gene mRNA by inserting a nontemplated G residue(s) at a conserved editing site (3'-UUUUUCCC-template strand). In the wild-type virus, three amino-coterminal P-gene-derived proteins, P, V, and W, are produced at frequencies of approximately 68, 29, and 2%, respectively. By applying the reverse genetics technique, editing-defective mutants were generated in cell culture. Compared to the wild-type virus, mutants lacking either six nucleotides of the conserved editing site or the unique C-terminal part of the V protein produced as much as 5, 000-fold fewer infectious progeny in vitro or 200,000-fold fewer in 6-day-old embryonated chicken eggs. In addition, both mutants were unable to propagate in 9- to 11-day-old embryonated specific-pathogen-free (SPF) chicken eggs. In contrast, a mutant (NDV-P1) with one nucleotide substitution (UUCUUCCC) grew in eggs, albeit with a 100-fold-lower infectious titer than the parent virus. The modification in the first two mutants described above led to complete abolition of V expression, whereas in NDV-P1 the editing frequency was reduced to less than 2%, and as a result, V was expressed at a 20-fold-lower level. NDV-P1 showed markedly attenuated pathogenicity for SPF chicken embryos, unlike currently available ND vaccine strains. These findings indicate that the V protein of NDV has a dual function, playing a direct role in virus replication as well as serving as a virulence factor. Administration of NDV-P1 to 18-day-old embryonated chicken eggs hardly affected hatchability. Hatched chickens developed high levels of NDV-specific antibodies and were fully protected against lethal challenge, demonstrating the potential use of editing-defective recombinant NDV as a safe embryo vaccine.
162 citations
TL;DR: F and HN gene sequence comparison showed a strong relationship to sequences derived from endemic Australian NDV rather than those of overseas viruses or wild bird isolates, closely related to two previously isolated 'ancestor' viruses that have the same unique HN extension sequence.
148 citations
TL;DR: The first complete genomic sequence of Marek's disease virus serotype 3 (MDV3), also known as turkey herpesvirus (HVT), is presented, which resembles alphaherpesviruses in genomic organization and gene content.
Abstract: Turkey herpesvirus (HVT) is a ubiquitous, nonpathogenic virus of domestic turkeys (15, 78–80), and it is classified as the third serotype within the Marek's disease virus (MDV) group of antigenically and genetically related lymphotropic avian herpesviruses (15). This group also includes MDV serotype 1 (MDV1), which is the etiologic agent of the globally and economically significant Marek's disease in chickens (15). MDV1 is pathogenic in chickens, causing cytolytic infection in B cells, latent infection in T cells, and induction of T-cell lymphoma. MDV2 is nonpathogenic or of low pathogenicity in chickens (15).
HVT is nonpathogenic in chickens, but it does induce a viremia which is associated with induction of protective immune responses against MDV1 (15). Chickens infected with HVT become persistently infected and maintain long-lasting immunity (15, 29, 44, 53, 80). HVT appears to replicate less efficiently in skin than does MDV1, a phenotype that may be involved in the relatively infrequent transmission of HVT among chickens compared to attenuated strains of MDV1 and MDV2 (15–17).
HVT and combinations of HVT and nonpathogenic strains of MDV1 and MDV2 have been used extensively and effectively as vaccines against virulent MDV1 since the early 1970s (15, 44, 53, 80). Other benefits of HVT vaccines include the ability to genetically modify the virus for expression of protective heterologous antigens and the potential for in ovo vaccination. HVT vectors expressing genes from Newcastle disease virus, infectious bursal disease virus, and infectious bronchitis virus confer protective systemic immune responses against these pathogens (19, 54, 58, 86). In ovo vaccination of late-stage (16- to 18-day) embryos with HVT leaves newly hatched chickens immune to challenge with pathogenic MDV1 (62, 63).
Although current vaccination strategies will effectively protect against most MDV1 isolates, they are not completely effective against newly emerging MDV1 strains of greater virulence (77). These strains which pose a constant threat to the poultry industry, are characterized by higher cytolytic activity, unusual tissue tropism, increased atrophy of lymphoid organs, immunosuppression, enhanced capacity to transform T cells, and earlier host death (77). The genetic basis underlying differences in viral virulence, oncogenicity, and host range among MDV strains is poorly understood.
Comparative genomics has proven useful in identifying genes with functions involving virulence and host range. The genomes of two MDV1 strains (GA and Md5) have been sequenced (45, 74), and the unique long and unique short (UL and US, respectively) regions of MDV2 are available (37). However, less than 30% of the HVT genome has been sequenced (5, 41, 43, 48, 68, 83, 85). Here we present the complete sequence of HVT strain FC-126 (Burmenester), with analysis and comparison to MDV1 and MDV2.
141 citations
TL;DR: A plasmid-only rescue system is used that allows the rapid generation of high-yield recombinant vaccine strains and the use of Newcastle disease virus recombinants expressing influenza virus haemagglutinin proteins of pandemic (epizootic) strains as novel vaccine vectors for use in animals and possibly humans.
Abstract: The potential threat of another influenza virus pandemic stimulates discussion on how to prepare for such an event. The most reasonable prophylactic approach appears to be the use of effective vaccines. Since influenza and other negative-stranded RNA viruses are amenable to genetic manipulation using transfection by plasmids, it is possible to outline new reverse genetics-based approaches for vaccination against influenza viruses. We suggest three approaches. First, we use a plasmid-only rescue system that allows the rapid generation of high-yield recombinant vaccine strains. Second, we propose developing second-generation live influenza virus vaccines by constructing an attenuated master strain with deletions in the NS1 protein, which acts as an interferon antagonist. Third, we suggest the use of Newcastle disease virus recombinants expressing influenza virus haemagglutinin proteins of pandemic (epizootic) strains as novel vaccine vectors for use in animals and possibly humans.
127 citations
TL;DR: Although the pathotyping results indicated a virulence increase of all passaged PPMV-1 isolates, clinical disease was limited to depression and some nervous signs in only some of the 4-wk-old specific-pathogen-free white leghorns inoculated intraconjunctivally with passaged virus.
Abstract: The virulence of six pigeon-origin isolates of Newcastle disease virus (NDV) was evaluated before and after passage in white leghorn chickens. Four isolates were defined as pigeon paramyxovirus-1 (PPMV-1) and two isolates were classified as avian paramyxovirus-1 (APMV-1) with NDV monoclonal antibodies. The four PPMV-1 isolates were passaged four times in chickens, and the APMV-1 isolates were passaged only once. Infected birds were monitored clinically and euthanatized. Tissues were collected for histopathology, in situ hybridization with a NDV matrix gene digoxigenin-labeled riboprobe, and immunohistochemistry with an anti-peptide antibody to the nucleoprotein. Mean death time, intracerebral pathogenicity index, and intravenous pathogenicity index tests performed before and after passage in chickens demonstrated increased virulence of the passaged PPMV-1 isolates and high virulence of the original isolates of APMV-1. Sequence analysis of the fusion protein cleavage site of all six isolates demonstrated a sequence typical of the virulent pathotype. Although the pathotyping results indicated a virulence increase of all passaged PPMV-1 isolates, clinical disease was limited to depression and some nervous signs in only some of the 4-wk-old specific-pathogen-free white leghorns inoculated intraconjunctivally. However, an increased frequency of clinical signs and some mortality occurred in 2 wk olds inoculated intraconjunctivally with passaged virus. Histologically, prominent lesions in heart and brain were observed in birds among all four groups inoculated with the PPMV-1 isolates. The behavior of the two pigeon-origin APMV-1 isolates when inoculated into chickens was characteristic of velogenic viscerotropic NDVs and included necro-hemorrhagic lesions in the gastrointestinal tract.
119 citations
TL;DR: The potential utility of an avirulent NDV as a vaccine vector is indicated after insertion of a foreign gene encoding chloramphenicol acetyltransferase between the HN and L genes of the full-length cDNA of a virulent Newcastle disease virus.
Abstract: A previous report showed that insertion of a foreign gene encoding chloramphenicol acetyltransferase (CAT) between the HN and L genes of the full-length cDNA of a virulent Newcastle disease virus (NDV) yielded virus with growth retardation and attenuation. The NDV vector used in that study was pathogenic to chickens; it is therefore not suitable for use as a vaccine vector. In the present study, an avirulent NDV vector was generated and its potential to express CAT protein was evaluated. The CAT gene was under the control of NDV transcriptional start and stop signals and was inserted immediately before the open reading frame of the viral 3′-proximal nucleocapsid protein gene. A recombinant NDV expressing CAT activity at a high level was recovered. The replication and pathogenesis of the CAT-expressing recombinant NDV were not modified significantly. These results indicate the potential utility of an avirulent NDV as a vaccine vector.
112 citations
TL;DR: The results demonstrate that genetically modified marker vaccines can be generated from small RNA viruses that lack non-essential genes.
90 citations
TL;DR: Analysis of the genes encoding the haemagglutinin and fusion proteins of Australian isolates of the virus demonstrated that Australian chicken strains of NDV could be differentiated from NDV isolated elsewhere, which demonstrated that NDV isolates causing the recent outbreaks of virulent disease were Australian viruses.
Abstract: Australia experienced outbreaks of virulent Newcastle disease (ND) in chickens in the state of New South Wales in the years 1998, 1999 and 2000. The disease had occurred previously in Australia in ...
01 Jan 2001
TL;DR: Control is possible, but this requires efficient applications of vaccines, and rigorous biosecurity, and suitable vaccines seem to be the only answer to the control of ND in village chickens.
Abstract: Newcastle disease virus (NDV) infects most avian species. The serious consequence is the disease (frequently fatal) that occurs when virulent strains of the virus infect domestic chickens. The epidemiology of Newcastle disease (ND) in commercial chickens is fairly well understood. Infected chickens are the usual source of virus, which can be transported mechanically by fomites or by people. Preventive measures include vaccination and attention to biosecurity. Village chickens are also susceptible to ND, which, in developing countries, is the most important constraint to rural poultry production. Similar epidemiological factors probably apply to the spread of NDV in commercial chickens and village chickens. Until recently, thermostable ND vaccines were not available for use in village chickens. Biosecurity is extremely difficult to practice at the village level. Both epizootic and enzootic ND are recognised in village chickens. Epizootics occur when virus is introduced to a susceptible population. Spectacular outbreaks with high mortalities result. Enzootic ND occurs when the virus transmits slowly in a partially immune population. In this case, there are too few susceptible birds to maintain an outbreak and the occasional birds that die do not come to veterinary attention. Possibly a breeding population of as few as 500 birds can sustain the virus, as indicated by computer modelling. Anecdotal evidence suggests that seasonal conditions favour the initiation of outbreaks. More likely, it is movement of poultry, especially through markets, that initiates and fuels an outbreak. Salvage sales increase the dissemination of virus once the disease is recognised. All village chickens are sold as live birds, for consumption or for breeding. It does not seem feasible to control this aspect of the epidemiology of the disease. Suitable vaccines seem to be the only answer to the control of ND in village chickens.
TL;DR: The Newcastle disease epizootic that commenced in Italy in May 2000 was due to a genotype VIIb virus that is indistinguishable from those causing sporadic outbreaks in Great Britain and Northern Europe in the late 1990s.
Abstract: Thirty-six representative velogenic strains of Newcastle disease virus isolated in Italy since 1960 were characterized by restriction site and partial sequence analyses of the fusion protein gene. Viruses belonging to the six known genotypes of Lomniczi et al . were found. Genotype IV, which was most probably the main epizootic group in Europe before the war, was responsible for outbreaks in the 1960s and persisted until the late 1980s in Italy. An epizootic peak in 1972 to 1974 coincided with the appearance of genotype V viruses that were present for more than a decade. Outbreaks in 1992 were caused by genotype VIIa viruses and were part of a contemporaneous epizootic of Far East origin that affected Western European countries. The Newcastle disease epizootic that commenced in Italy in May 2000 was due to a genotype VIIb virus that is indistinguishable from those causing sporadic outbreaks in Great Britain and Northern Europe in the late 1990s. Isolated cases yielded a variant of genotype VI (reference e...
TL;DR: It is suggested that long-term selection for increased 16-wk BW might have resulted inChanges in the immune system, as indicated by changes in the relative weights of the spleen and bursa of Fabricius and phagocytic activity.
TL;DR: The recombinant interferon suppressed I BDV plaque formation in a dose-dependent manner and ameliorated IBDV and Newcastle disease virus infection in both specific-pathogen-free (SPF) and commercial chickens.
Abstract: The in vitro and in vivo effects of chicken interferon alpha on infectious bursal disease virus (IBDV) infection were investigated in this study. A cDNA of interferon alpha was first cloned from a Chinese strain chicken Shiqi by reverse transcription-polymerase chain reaction. The deduced amino acid sequence has one amino acid substitution with chicken interferon alpha 1 at residue 65 (N to S) and two amino acid substitutions with chicken interferon alpha 2 at residues 50 (N to S) and 58 (P to L), respectively. A prokaryotic expression system was employed to produce a large quantity of recombinant protein. Recombinant interferon was purified in a one-step process, and an optimal refolding process was devised. About 51% recombinant protein from inclusion bodies was refolded, and the final yield of the recombinant interferon reached 24.66 mg/liter culture. The recombinant interferon suppressed IBDV plaque formation in a dose-dependent manner and ameliorated IBDV and Newcastle disease virus infection in both specific-pathogen-free (SPF) and commercial chickens. The antiviral effect of interferon alpha is more significant in commercial chickens than in SPF chickens, and the route of administration affects the efficacy of interferon therapy. This is the first reported study of the effects of interferon alpha on IBDV infection.
TL;DR: In this review, some recent developments with many avian viruses are highlighted, including Newcastle disease virus; circoviruses in canary and pigeon; infectious bursal disease virus (Gumboro disease virus); avian adenovirus; and avian encephalomyelitis virus, a picornavirus related to hepatitis A virus.
Abstract: Polymerase chain reaction (PCR)-based approaches to the detection, differentiation and characterization of avian pathogens continue to be developed and refined. The PCRs, or reverse transcriptase-PCRs, may be general, designed to detect all or most variants of a pathogen, or to be serotype, genotype or pathotype specific. Progress is being made with respect to making nucleic acid approaches more suitable for use in diagnostic laboratories. Robotic workstations are now available for extraction of nucleic acid from many samples in a short time, for routine diagnosis. Following general PCR, the DNA products are commonly analyzed by restriction endonuclease mapping (restriction fragment length polymorphism), using a small number of restriction endonucleases, based on a large body of sequence data. Increasingly, however, nucleotide sequencing is being used to analyze the DNA product, in part due to the expanding use of non-radioactive sequencing methods that are safe and enable high throughout. In this review, I highlight some recent developments with many avian viruses: Newcastle disease virus; circoviruses in canary and pigeon; infectious bursal disease virus (Gumboro disease virus); avian adenoviruses, including Angara disease/infectious hydropericardium virus, haemorrhagic enteritis virus of turkeys, and egg drop syndrome virus; avian herpesviruses, including infectious laryngotracheitis virus, duck plague virus, psittacine herpesvirus (Pacheco's parrot disease virus), Marek's disease virus and herpesvirus of turkeys; avian leukosis virus (associated with lymphoid leukosis or myeloid leukosis, and egg transmission); avian pneumoviruses (turkey rhinotracheitis virus); avian coronaviruses, including infectious bronchitis virus, turkey coronavirus and pheasant coronavirus; astrovirus, in the context of poult enteritis and mortality syndrome, and avian nephritis virus; and avian encephalomyelitis virus, a picornavirus related to hepatitis A virus.
Journal Article•
TL;DR: Application of one-step RT-PCR to various NDV samples, including wild-type virulent isolates and avirulent vaccine strains, demonstrated the potential for rapid identification (3-4 h) of NDV isolates as well as the differentiation of virulent from avirulence strains.
Abstract: A triple one-step RT-PCR was developed to screen and differentiate virulent from avirulent Newcastle disease virus (NDV) isolates. Three sets of oligonucleotides were designed, each specific for amplifying NDV fusion protein gene-specific RNA from virulent, avirulent or all isolates respectively. The sensitivity of one-step RT-PCR was determined using viral RNA extracted from serially diluted NDV-infected allantoic fluid and found to be 10(-5) HA units. Application of one-step RT-PCR to various NDV samples, including wild-type virulent isolates and avirulent vaccine strains, demonstrated the potential for rapid identification (3-4 h) of NDV isolates as well as the differentiation of virulent from avirulent strains.
TL;DR: It was concluded that the addition of BM to the diet of chickens did not significantly influence the immune response to IB, IBD and ND vaccines in meat and SPF chickens.
Abstract: Shafey, T.M., Al-Mufarej, S., Shalaby, M.I. and Jarelnabi, A.J. 2001. Effects of mannan oligosaccharides on antibody response to infectious bronchitis, infectious bursal disease and Newcastle disease in chickens. J. Appl. Anim. Res., 19: 117–127. The effects of feeding a mannan oligosaccharide (Bio-Mos) from 0 to 3g/kg diet on 1 to 35 day serum total protein, albumin and globulin and on antibody response to infectious bronchitis (IB), infectious bursal disease (IBD) and Newcastle disease (ND) vaccines of meat (experiment 1) and specific pathogen-free (SPF) (experiment 2) chickens were examined. A general vaccination program was used against IB, IBD and ND with half of the birds per diet receiving a booster dose of IB and ND vaccines at 12 day of age in experiment 1. Whilst, all birds in experiment 2 were vaccinated with the booster dose, Bio-Mos (BM) did not influence antibody titers of IB, IBD and ND and serum albumin of chickens. Serum globulin and total protein were influenced by dietary addit...
TL;DR: Newcastle disease viruses isolated from chickens and guinea fowl were characterized as viscerotropic, velogenic strains on the basis of their mean death time, intracerebral pathogenicity index, intravenous pathogenivity index and cloacal and conjunctival mean deathTime.
Abstract: Newcastle disease viruses isolated from chickens and guinea fowl were characterized as viscerotropic, velogenic strains on the basis of their mean death time, intracerebral pathogenicity index, intravenous pathogenicity index and cloacal and conjunctival mean death time. The pathogenesis of the disease caused by both the strains was studied in 4-week-old guinea fowl. Both strains had an incubation period of 5 days and the birds showed dullness, depression, anorexia, diarrhoea and paralysis of the legs. They also exhibited nervous signs such as incoordination, muscle tremors and trembling of the neck at the advanced stage of the disease. Mortality reached 52% in the group infected with the chicken isolate but it was only 8% in the birds infected with the guinea fowl isolate. No specific changes were observed at post-mortem examination except haemorrhages at the tip of the glands of the proventriculus and in the caecal tonsil. Changes in the lymphoid organs and brain were always present in both the groups. Despite the low mortality, the guinea fowl isolated had multiplied in various organs in the birds. In both groups, the frequency of virus isolation increased from 5 to 10 days post infection.
TL;DR: The in oVO vaccine causes a reduction of NDV immunoresponse, as testified by lowest geometric mean titer in group I (SPF chickens vaccinated against IBDV in ovo and against NDV at 11 days).
Abstract: The study was divided into two experiments. In the first experiment, the efficacy of in ovo intermediate vaccine against infectious bursal disease virus (IBDV) was determined by challenge at 21 days of age with virulent IBDV in specific-pathogen-free (SPF) and commercial chickens. This vaccine was able to induce active immunity and to protect SPF chickens to challenge; protection was not complete in commercial chickens, as testified by bursal lesions, bursal index after challenge, and vaccine immunoresponse. In order to detect field and vaccinal viruses, immunoperoxidase staining, enzyme-linked immunosorbent assay, capture, and reverse transcriptase-polymerase chain reaction (RT-PCR) were tested; the RT-PCR was more effective at detecting both kind of viruses. In the second experiment, the immunosuppressive effect of in ovo vaccination was determined by evaluating the immunoresponse against Newcastle disease virus (NDV) vaccination effected at 10 days in both SPF and commercial chickens vaccinated in ovo. The in ovo vaccine causes a reduction of NDV immunoresponse, as testified by lowest geometric mean titer in group I (SPF chickens vaccinated against IBDV in ovo and against NDV at 11 days). In commercial chickens, immunoresponse to NDV vaccination was not influenced by in ovo vaccination.
TL;DR: The results suggest that suspected immunosuppression in a commercial flock could be assessed within 2-3 days by challenging birds with iNDV and measuring the amounts of ChIFN-alpha and ChIFn-gamma mRNA in blood obtained 2-4 h later.
Abstract: Avian diseases, including such viral infection as infectious bursal disease, infectious anemia, and Marek's disease, often cause immunosuppression, leading to more severe infection, problems with secondary infection, and inadequate responses to vaccination. Immunosuppression thus causes serious economic losses in commercial poultry production. To date, methods for assessing immune status have been too slow to be of practical help. Reasoning that immunosuppression should be reflected by reduced production of interferons (IFN) in response to a viral antigen, we have developed competitive nucleic acid hybridization microtiter plate assays for chicken IFN-α (ChIFN-α) and ChIFN-γ mRNA. To evaluate the assay, chickens were challenged with inactivated Newcastle disease virus (iNDV). Whole blood samples were collected at various times subsequently and preserved with a cationic detergent. Later, total RNA was extracted, and mRNA for both ChIFN-α and ChIFN-γ was measured. Both rose from undetectable levels to reach...
Patent•
30 Oct 2001
TL;DR: The NDV mutant is not able to express an immunodominant epitope of the nucleoprotein (NP) as discussed by the authors, which is suited as a marker vaccine strain.
Abstract: The present invention provides a NDV mutant that is suited as a marker vaccine strain. The NDV mutant is not able to express an immunodominant epitope of the nucleoprotein (NP).
TL;DR: It is evident that TRT virus did not play a causal role in SHS in commercial broiler flocks in Greece, but in this condition, other viruses (IBV, NDV), mycoplasmas, or bacteria may be involved, and environmental conditions seem to be essential to the occurrence and severity of the disease.
Abstract: From 50 commercial broiler flocks included in a study concerning respiratory disease, signs of swollen head syndrome (SHS) were shown in eight. Postmortem examination was performed in eight birds showing signs of SHS from each flock. The trachea and head from each bird were collected for laboratory investigation. An enzyme-linked immunosorbent assay (ELISA) was used for the detection of viral and avian mycoplasma antigens in the trachea, and bacteriologic examinations were performed from the infraorbital sinuses of the infected birds. According to the ELISA results, the most frequently detected antigen in the trachea was Mycoplasma synoviae (six flocks, 75%), followed by infectious bronchitis virus (IBV) (five flocks, 62.5%), avian adenovirus (four flocks, 50%), avian reovirus (three flocks, 37.5%), Mycoplasma gallisepticum (one flock, 12.5%), and Newcastle disease virus (NDV) (one flock, 12.5%). Turkey rhinotracheitis (TRT), infectious laryngotracheitis, and avian influenza viral antigens were not detected. Experimental assays for characterization of NDV and IBV isolates showed that they were strains of low virulence (evidently vaccine strains). Bacteriologic examinations from the infraorbital sinuses of the affected birds resulted in the isolation of Escherichia coli (seven cases, 87.5%) and Staphylococcus spp. (one case, 12.5%). It is evident that TRT virus did not play a causal role in SHS in commercial broiler flocks in Greece, but in this condition, other viruses (IBV, NDV), mycoplasmas, or bacteria may be involved, and environmental conditions seem to be essential to the occurrence and severity of the disease.
23 Dec 2001-Journal of Veterinary Medicine Series B-infectious Diseases and Veterinary Public Health
TL;DR: The study demonstrates the absence of NDV antibodies in the birds investigated on one hand, but also indicates a health hazard for numerous avian species due to the risk of infections with C. psittaci, APV or PDV.
Abstract: From 1998 to 1999, a total of 128 blood samples were collected from scarlet macaws (Ara macao), kept in captivity in 11 different aviaries located in six provinces of Costa Rica. The sera were examined for antibodies directed against Chlamydophila psittaci, Newcastle disease virus (NDV), avian polyoma virus (APV), and Pacheco disease virus (PDV). Testing by enzyme-linked immunosorbent assay (ELISA), showed 16 (12.39%) of the samples (n = 129) exhibited antibodies directed against C. psittaci. Employing haemagglutination inhibition tests for NDV antibodies, all of the samples were found to be negative. The prevalence of antibodies specific for APV was tested with a blocking ELISA and serum neutralization tests (SNT) and 12 of 128 samples (9.37%) were found to be positive with both tests. In SNT, two out of 128 samples (1.56%) were positive for PDV. This is the first description of the serological status in scarlet macaws in captivity in Costa Rica. The study demonstrates the absence of NDV antibodies in the birds investigated on one hand, but also indicates a health hazard for numerous avian species due to the risk of infections with C. psittaci, APV or PDV.
01 Jan 2001
TL;DR: It was concluded that NDV4-HR and I-2 strains are avirulent, innocuous, efficacious, immunogenic and suitable for use in the control of ND in Mozambique and that vaccine administered by eye-drop gave better results than vaccine administered in the drinking water or by oral drench.
Abstract: nThe Australian strains of avirulent, thermostable Newcastle disease virus designated NDV4-HRnand I-2 were tested in the laboratory and under field conditions in Mozambique. An overview ofnthis work is presented. Under experimental conditions, both vaccine strains provided protection tonall vaccinated birds and those in contact with them against a local virulent strain of ND virus,nV868. Field trials confirmed these results. In addition, it was shown that vaccine administered byneye-drop gave better results than vaccine administered in the drinking water or by oral drench.nThere were no adverse reactions to the vaccines and it was concluded that NDV4-HR and I-2nstrains are avirulent, innocuous, efficacious, immunogenic and suitable for use in the control of NDnin Mozambique. Factors contributing to the successful implementation of the field trials are alsondiscussed.
TL;DR: The results demonstrate that the field isolates with a more thermostable hemagglutinin could have been derived by selection from the heterogenous NDV populations in vaccine strains and that minor antigenic changes may be a result of that selection.
Abstract: SUMMARY. In a study of low-virulence Newcastle disease virus (NDV) isolates from poultry, 38% of the isolates had a more thermostable hemagglutinin than the lentogenic reference strains B1 and La Sota or live vaccines derived from those strains. Whether those strains with a more thermostable hemagglutinin are truly indigenous or whether they could have originated from vaccines used in the flocks was unknown. Seven monovalent NDV vaccines of B1 or La Sota type and reference B and La Sota strains were heat treated at 56 C to select variants more thermostable than the parent virus. Four thermal treatment cycles were completed, and virus propagated from the second and fourth heat treatments was assayed for changes in thermostability and antigenicity. The hemagglutinin thermostability of all vaccine and reference strain variants increased from the initial -10 min to >120 min after four treatments. Antigenic changes evaluated by hemagglutination inhibition against NDV monoclonal antibodies identified changes in only the heat-treated La Sota strains. The results demonstrate that the field isolates with a more thermostable hemagglutinin could have been derived by selection from the heterogenous NDV populations in vaccine strains and that minor antigenic changes may be a result of that selection.
TL;DR: The results suggested that thrombocytopenia was the end result of a direct viral damage to bone marrow precursor cells to be the main causes of haemorrhages in this animal model.
Abstract: Galindo-Mun iz F., N. L. Calderon, M. N. Charles, I. G. Tellez, T. I. Fortoul: Haematological and Histological Findings in Experimental Newcastle Disease. Acta Vet. Brno 2001, 70: 185-189. To obtain more information about pathogenesis of haemorrhages in Newcastle disease, blood cells counts with special emphasis on thrombocytes were performed in 25 specific pathogen-free chickens experimentally infected by ocular instillation of 10 6 embryo-lethal doses 50% of a velogenic viscerotropic strain of Newcastle disease virus (Chimalhuacan strain); five control chickens were included. Histological evaluation of the bone marrow, the brain, the kidneys, the lungs and the proventriculus was carried out. Birds were killed at 24 h post infection, followed by 12 h intervals. Whole blood and tissue samples were collected. In the bone marrow early necrosis of haematopoietic islands was noted at 48 hpi. At 60 hpi, an increase in heterophil and a decrease in monocyte and lymphocyte counts was observed; thromboblasts showed basophilia, nuclear and cytoplasmic vacuolation. During the same period, swelling and vacuolation of capillary endothelial cells were evident, mainly in the lungs. We consider thrombocytopenia and endothelial damage to be the main causes of haemorrhages in this animal model. A significant reduction at 72 h post infection (hpi) of thrombocyte counts and multifocal necrosis of bone marrow cells was observed. Our results suggested that thrombocytopenia was the end result of a direct viral damage to bone marrow precursor cells.
TL;DR: Flocks are managed with the forefront knowledge in biosecurity, housing, permanent evaluation of critical points and quality and vaccination programs, which guarantee the prevention of most health problems.
Abstract: Avian influenza is an exotic disease in the Brazilian poultry. The National Avian Health Surveillance Program (PNSA) maintains permanent monitoring of AVES of all domestic species, including imported genetic material for the poultry industry, for example chickens (Gallus gallus formadomestica), turkeys (Meleagris gallopavo formadomestica), quail (Coturnix coturnix japonica), ducks (Anas), elite, grand grandparent and grandparent stocks for layers and broilers, as well as species more recently exploited for production, for example, the exotic ostriches (Struthio camelus) or native rheas (Rhea americana). The breeding stocks are monitored by regular sampling for serology, virology and bacteriology, principally looking for Newcastle disease, influenza, salmonellas and mycoplasmas, as established by the PNSA, in addition to monitoring vaccination responses to, for example, infectious bursal disease and infectious bronchitis. The PNSA establishes the rules for the control and eradication of Newcastle disease and avian influenza (Projeto de Vigilância..., 2001), including the need for differential diagnosis, according to the following major actions: I. Notification of outbreaks (and laboratory confirmation at the LARA-Campinas); II. Sanitary assistance to the outbreaks; III. Disinfection and sanitation measures; IV. Sanitary slaughter; V. Sanitary depopulation; VI. Vaccination of flocks and emergency strategies; VII. Control and monitoring of susceptible flocks; VIII. Other sanitary measures; The active surveillance and outbreak attention policies require the diagnosis and differential diagnosis of ND and AI, following the code described by OIE and the PNSA, as follows: 1- Zoning, interdiction and sampling for laboratory confirmation; 2- Registry of AVES, including species, category and numbers; applicable to a 10 km radius: restriction to transportation of animals and materials possible source of infection and propagation; disinfection of sites of entry and exit to affected properties; epidemiological surveillance; 3- Laboratory confirmation by isolating and characterizing AIV: hemagglutinating agent isolated in SPF eggs not inhibited by NDV specific serum, characterized as AIV by detecting antigens of the nucleoprotein and/or matrix and subtyped by assaying for hemagglutinin and neuraminidase subtypes (immunodiffusion, enzyme immunoassays or molecular methodology); 4- Slaughter and cremation of all avian individuals, residues, meats and eggs of all affected and neighboring properties (3 km radius), cleaning and disinfection of premises; sanitary depopulation for 21 days (minimum). 5- Allow transportation for slaughter or incubation within the vigilance area (10 km radius). 6- Prohibit fairs, markets, expositions etc., within the vigilance area (10 km radius). 7- Apply these measures for a minimum of 21 days after disinfection (which follows slaughter, cremation and cleaning) and prohibit transportation of animals and residues/products of properties within the protection area (3 km radius) and for 15 days within the vigilance area (10 km radius). The certification of HPAIV area is according to OIE and PNSA regulations and considers Brazil as a free country, applicable as follows: 1- HPAIV is not diagnosed by the active surveillance for the last 3 years; 2- 6 months after an outbreak of HPAIV is diagnosed, birds and residues/products are destroyed. The major species (chickens and turkeys) maintained in the Brazilian poultry industry employ the state-of-the-art production technology. Flocks are managed with the forefront knowledge in biosecurity, housing, permanent evaluation of critical points and quality and vaccination programs, which guarantee the prevention of most health problems. The geographic localization of the Brazilian poultry industry may also play a role in the absence of influenza outbreaks, in addition to the lower rate of replication of AIV in migratory birds during their subtropical season. Migratory routes may also concentrate in areas not occupied by poultry industry. Added to that, the biosecurity/housing and quality system of the industry may represent the step further to prevent health problems caused by transmissible infectious diseases such as influenza, considering that, for instance, all chicken and turkey industrial flocks are kept in houses, in contrast to open field farming, especially for ducks, geese and turkeys, kept on migratory routes of countries facing influenza problems.
01 Jan 2001
TL;DR: Thermostable Newcastle disease vaccines, locally produced and widely distributed, would allow village chickens to contribute fully to alleviating poverty and improving nutrition in rural areas, and bases this assertion on his experience with control of Newcastle disease since 1984.
Abstract: Robust vaccines are required to protect village chickens against Newcastle disease. Thermostable vaccines derived from avirulent Australian strains of Newcastle disease virus (strains V4 and I-2) have proved successful for this purpose. These vaccines have been developed through ACIAR projects and have been adopted by other international aid agencies. It is now possible to offer integrated workshops in which administrators and field workers are trained in the use of thermostable vaccines, poultry-specific extension activities and gender aspects of poultry production. At the same time, laboratory workers are taught the skills required to produce and test thermostable vaccine on a small scale, and to assure the quality of the product. Vaccine seed material is supplied without cost. Recent events in Australia have led to some concern among potential users of the vaccine. Virulent strains of Newcastle disease virus have apparently risen from the avirulent strains that have been circulating in Australia for at least 30 years. Some have suggested that the virulent strains of Newcastle disease virus first recognised in 1926 were derived by a series of mutations from pre-existing avirulent viruses. The virulence of strains of Newcastle disease virus is currently judged by the sequence of amino acids at the cleavage site of the viral fusion (F) protein. Work in several laboratories has indicated that the sequences in V4 and I-2 are similar to those in other mild vaccine strains. One mesogenic vaccine strain used in developing countries has the same sequences as velogenic viruses. It is also argued that the Australian ‘virulent’ viruses do not produce a disease with high mortality and would be insignificant pathogens compared with Newcastle disease viruses that circulate in Africa and Asia. Thermostable Newcastle disease vaccines, locally produced and widely distributed, would allow village chickens to contribute fully to alleviating poverty and improving nutrition in rural areas. Suitable systems of extension and cost recovery would make the enterprise sustainable.