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Nucleotide sequence of the envelope protein genes of a highly virulent, neurotropic strain of Newcastle disease virus.

The envelope glycoproteins of Newcastle disease virus (NDV), hemagglutinin-neuraminidase (HN) and fusion (F) proteins, play important roles in determining the host immune response and the virulence of that particular virus strain. The complete nucleotide sequence of the HN and F genes of a highly neurovirulent strain of NDV (Texas G. B., 1948) was determined in an effort to study the molecular basis of this strain's neurotropic properties. Comparison of the predicted amino acid sequences for the HN and F among the American NDV strains revealed that the Texas G. B. and Beaudette C envelope genes are closely related to each other and are less closely related to the avirulent B1 Hitchner strain. We have found 11 amino acid changes in the predicted HN protein between the Beaudette C and Texas G. B. strain but only 2 conservative amino acid changes (amino acids 11 and 197) in the F protein between these two strains. Although the virulence of NDV strains has been related to sequences at the cleavage site of F0, the property of neurovirulence cannot depend solely upon these sequences because there are no sequence differences between the Beaudette C and Texas G. B. strains. We suggest that the neurovirulence phenotype could be due to the molecular properties of the HN protein; however, we cannot exclude the possibility that the two conservative amino acid differences between the two F proteins could also play a role in determining the phenotypic differences between these two virus strains.

Amino Acid Sequence↗

[Newcastle disease--seroepidemiologic study of a highly contagious epizootic in poultry and in wild birds in Switzerland].

Newcastle disease (ND) is a highly contagious viral disease particularly of domestic poultry. Switzerland is currently declared free from ND. A serosurvey using an ELISA was performed to investigate infections with ND-Virus (NDV) in 260 Swiss laying hen flocks, 169 backyard poultry flocks and 1576 wild birds. For laying hen flocks, a stochastic model was applied to analyse the results from serological testing. Four laying hen flocks were identified as NDV-seropositive, and the true NDV seroprevalence in this population was most likely between 1.3 and 1.5%. NDV antibodies were also detected in five of the 169 backyard poultry-flocks. ND-antibody positive birds were found in 10% of all wild birds examined, with the highest proportions among cormorants, grebes, birds of prey, owls, and swifts. The study indicated that positive flocks must have been in contact with NDV strains causing sub-clinical infection, since no clinical signs had been observed. Moreover, trade of poultry or poultry eggs was considered to be an important factor associated with seropositivity in backyard poultry flocks. Contact to wild birds did not seem to be of major importance.

Animals↗

[Newcastle disease in southern Chad: peak epidemic periods and the impact of vaccination].

In spite of its universally acknowledged importance, backyard chicken production is still being hampered by Newcastle disease in some parts of the world. In Chad, the disease has been reported almost everywhere in the country and confirmed in several regions, but there are no control measures in place. A survey was conducted at three sites in south-eastern Chad in July and August 2001, based on face-to-face interviews with 20% of the peasant farmers keeping chickens at these sites. The aim was to collect information on peak epidemic periods and on ways in which the infection spreads. The survey revealed that the peak epidemic periods for Newcastle disease are April, during the mango harvesting and selling period, and December, when trade increases for the seasonal festivities. The survey also showed that peasant farmers attach great importance to chicken farming. The survey was followed by a vaccination trial in November 2001 and February 2002, using the La Sota strain administered ocularly. All of the birds vaccinated during the trial were successfully protected from the disease and both chicken production and the income of the villagers increased. The authors conclude that in order to sustain poultry farming and maximise production in the southern zone, vaccination programmes must be urgently introduced, campaigns to raise awareness of Newcastle disease should be carried out and financial support to pay for vaccines should be provided. Efforts to combat other causes of poultry mortality must also be undertaken.

Animals↗

Induction of C3 expression in astrocytes is regulated by cytokines and Newcastle disease virus.

Synthesis of complement proteins and their regulation in resident cells of the central nervous system are important pathophysiologic factors that can affect the outcome of inflammatory central nervous system diseases. Primary cultures of rat astrocytes constitutively express C3 mRNA and produce C3 protein; both of them were enhanced by LPS or by a live as well as inactivated Newcastle disease virus, a neurotropic paramixovirus. TNF, IL-1 beta, and IL-8 also increased the levels of C3 mRNA and protein whereas IL-1 alpha and IL-6 had no effect, although all of these cytokines are inducible by LPS. LPS stimulation in the presence of cycloheximide decreased the LPS-mediated C3 mRNA induction by 60%. These data suggest that LPS effect on C3 regulation is mediated directly by LPS as well as by LPS-induced cytokines. Interestingly, C3 mRNA induced by Newcastle disease virus or inactivated Newcastle disease virus was inhibited by protein kinase inhibitors, H-7 and staurosporine, whereas these inhibitors had no effect on C3 induction mediated by LPS or cytokines, indicating the existence of different signal transduction pathways.

Alkaloids↗

Pathotyping of Newcastle disease viruses by RT-PCR and restriction enzyme analysis.

The technique of RT-PCR and restriction enzyme analysis was standardized to detect and differentiate Newcastle disease viruses. Digestion of RT-PCR-amplified, F gene sequences encoding for the cleavage activation sites of fusion protein with restriction enzymes AluI, BglI, HaeIII, HinfI, HhaI, RsaI, StyI and TaqI was carried out in order to characterize Newcastle disease viruses of varying pathogenicity. Restriction enzyme digestion of the amplicons by BglI and HhaI could group eight viruses, both field isolates and known vaccine strains, into lentogenic, mesogenic and velogenic pathotypes. By employing this technique directly on a clinical sample, Newcastle disease virus of the lentogenic pathotype could be detected.

Animals↗

Neutralization of viruses by homologous immune serum. I. Quantitative studies on factors which affect the neutralization reaction with Newcastle disease, influenza A, and bacterial virus T3.

Neutralization experiments with Newcastle disease, influenza A, or bacterial virus, T(3), reveal, under all conditions studied, a linear relationship between the logarithm of the serum dilution end point and that of the quantity of virus used. With Newcastle disease and influenza A, the slope of the neutralization line varies markedly with the host-cell system used and in the chick embryo is strikingly affected by the route of inoculation. The other variables examined have no definite effect upon the slope. Reactivation of neutralized influenza virus is demonstrable in the chick embryo on dilution of the mixture. There appears to be an inverse relationship between the degree of susceptibility of a host to infection with influenza A virus and the neutralizing titer of a serum as measured in that host. With the T(3)-serum system, comparable results are obtained when the number of unneutralized virus particles chosen as the end point is varied widely.

Animals↗

Progression of tracheal lesions in turkeys exposed by aerosol to LaSota strain of Newcastle disease virus.

Five-week-old turkeys were exposed by aerosol to the LaSota strain of Newcastle disease virus. Poults were killed on days 2, 4, 6, 8, 10, 12, and 14 postexposure, and tracheas were processed for virus quantitation and histologic examination. Newcastle disease virus was recovered at a high titer from all tracheas collected 2, 4, and 6 days postexposure. The initial tracheal lesion observed on day 2 was swelling of ciliated columnar and mucous gland cells. Some of the affected cells contained intracytoplasmic inclusions. Cell swelling and degeneration were followed by epithelial cell proliferation, fibrinopurulent exudation, and lymphocytic infiltration. Epithelial cell proliferation was most severe on days 4 and 6, when tracheas were lined with several layers of immature cells. Lymphoid nodules appeared on day 6 and persisted up to day 14. From day 8 on, there was regression of the proliferative lesion accompanied by differentiation of the immature epithelium. By day 14, the tracheal mucosa regained its normal histologic appearance.

Aerosols↗

Immunohistochemical detection of Newcastle disease virus in chickens.

An immunoperoxidase histochemical technique utilizing a monoclonal primary antibody was developed for detection of Newcastle disease virus (NDV) antigen in tissues from chickens. The technique was applied to trachea, lung, spleen, Harderian gland, and cecal tonsil harvested from specific-pathogen-free (SPF) chickens at 2, 5, 7, 10, and 14 days postinoculation (PI) with NDV, and to corresponding tissues from commercial broiler chickens representing 30 cases of spontaneous respiratory disease. Positive staining occurred in the cytoplasm of respiratory epithelial cells in the trachea or bronchi of NDV-inoculated SPF chickens at 5 and 7 days PI. Staining also occurred in the respiratory epithelium of the trachea and bronchi of commercial broilers from seven of 30 cases of spontaneous respiratory disease. These results indicate that the immunoperoxidase technique has value as a rapid diagnostic test for Newcastle disease.

Animals↗

Onset of protective immunity in chicks after vaccination with a recombinant herpesvirus of turkeys vaccine expressing Newcastle disease virus fusion and hemagglutinin-neuraminidase antigens.

The onset of protective immunity from lethal Newcastle disease virus (NDV) challenge of chicks was determined after vaccination with a recombinant herpes virus of turkeys (HVT) expressing the fusion and hemagglutinin-neuraminidase proteins of NDV. One-day-old specific-pathogen-free chicks devoid of maternal antibodies to NDV were vaccinated with 130 to 3300 plaque forming units of HVT (depending on the trial) and then challenged at 4, 7, 10, and 14 days postvaccination (DPV) with a neurotropic velogenic strain of NDV (GB Texas). The recombinant vaccine afforded 0%, 35-75%, 85%, and 94-100% protection when the vaccinated birds were challenged at 4, 7, 10, and 14 DPV, respectively. In all trials, challenge caused 100% mortality in unvaccinated control chicks. Newcastle disease virus was reisolated from the lung, liver, spleen, and brain of birds dying in all trials regardless of vaccine dosage or time of challenge, except when challenge occurred at 14 DPV.

Animals↗

Thrombocytopenia in Newcastle disease: haematological evaluation and histological study of bone marrow.

A Newcastle disease virus (NDV) isolated in Mexico and called Chimalhuacan strain was characterised by gene F restriction enzyme analysis and found to be a genotype II velogenic virus. Haematological evaluations and histological studies of bone marrow were conducted on chickens experimentally infected with the Chimalhuacan virus and on control chickens. Within 72 hours post infection (hpi), a 50% decrease in thrombocyte and monocyte counts and a complete cellular depletion in bone marrow islands were evident in the infected group. These findings suggest that the Chimalhuacan strain of NDV causes an early and severe damage of the haematopoietic cells including thrombocyte precursors, which might explain the marked thrombocytopenia detected in early stages of this disease.

Animals↗

Micro-radioimmunoassay for antibodies to Newcastle disease virus in the chicken.

An indirect micro-radioimmunoassay is described in which chicken anti-Newcastle disease virus antibody was detected, with radioactively labeled rabbit anti-chicken Fab, on virus-infected microcultures of chick embryo fibroblasts. Newcastle disease virus-infected microcultures were formalin fixed and stored at 4 degrees C for up to 4 months without affecting the sensitivity of the test. The micro-technique was found to be highly sensitive and specific assay of anti-viral antibody and may allow detection of immunoglobulin class of anti-Newcastle disease virus antibody.

Agammaglobulinemia↗

Nucleotide sequence and phylogenetic analysis of Newcastle disease virus isolates from recent outbreaks in Taiwan.

Portions of the hemagglutinin neuraminidase (HN) gene of Newcastle disease virus (NDV) isolates from two recent outbreaks were sequenced to investigate epidemiology of this disease in Taiwan. These NDV isolates were all viscerotropic velogenic according to the clinical lesions produced in chickens. Sequence data were obtained from 14 NDV isolates (12 from 1995 and 2 from 1984). All isolates differed in their nucleotide sequences (from 0.3 to 15.3%), and represented potentially different strains of NDV. Phylogenetic analysis revealed that these isolates are closely related to viruses isolated from Japan and Malaysia. Some viruses isolated in 1995 appeared to evolve from viruses isolated in 1984. The results suggest that the 1995 outbreak of Newcastle disease (ND) in Taiwan may have been caused by multiple strains of velogenic NDV that have cocirculated in Taiwan for some time. Moreover, NDV isolates from racing pigeons were very similar to isolates from chickens in the same period, suggesting that both domestic and free-living birds were involved in the spread of ND in Taiwan.

Amino Acid Sequence↗

Fractionation of Newcastle disease virus by chromatography on diethylaminoethyl cellulose.

Wilson, Dwight E. (Rensselaer Polytechnic Institute, Troy, N.Y.). Fractionation of Newcastle disease virus by chromatography on diethylaminoethyl cellulose. J. Bacteriol. 84:295-301. 1962.-The L. Kansas and NK strains of Newcastle disease virus were chromatographed on diethylaminoethyl (DEAE) cellulose ion-exchange columns. L. Kansas virus eluted from DEAE columns showed one peak of hemagglutinating and infective particles. Two peaks of hemagglutinins and one peak of infective particles were observed when the NK strain was chromatographed, indicating that the stock virus contained a noninfectious hemagglutinating component. Treatment of the noninfectious particles with Genetron 113 resulted in an increase in the ratio of infective to hemagglutinating particles. The Genetron-treated noninfectious particles were also eluted from the DEAE column at a higher salt concentration than the untreated noninfectious particles. The results indicate that the Genetron treatment removes inhibitors of infectivity bound to the noninfectious virus particle.

Animals↗

Analysis of matrix protein gene nucleotide sequence diversity among Newcastle disease virus isolates demonstrates that recent disease outbreaks are caused by viruses of psittacine origin.

Nucleotide sequence analysis was completed for isolates of Newcastle disease virus (NDV; avian paramyxovirus 1) from 1992 outbreaks in cormorants and turkeys. These isolates were of the neurotropic velogenic type. The cormorant and turkey NDV isolates had the fusion protein cleavage sequence 109SRGRRQKR/FVG119, as opposed to the consensus sequence 109SGGRRQKR/FIG119 of most known velogenic NDV isolates. The R for G substitution at position 110 may be unique for the cormorant and turkey isolates. For comparative purposes, nucleotide sequencing and analysis of the conserved matrix protein gene coding region were completed for isolates representing all pathotypes. Phylogenetic relationships demonstrated that there are two major groups of NDV isolates. One group includes viruses found in North America and worldwide, such as B1, LaSota, Texas/GB, and Beaudette/C. The second group contains isolates, such as ulster/2C, Australia/Victoria, and Herts/33, considered exotic to North America. Within this second group are viruses of psittacine origin. The viruses from 1992 outbreaks of Newcastle disease in North America, and an isolate thought to have caused the major outbreak in southern California during the 1970s, are most closely related to an NDV isolate of psittacine origin.

Amino Acid Sequence↗

Duration of excretion of virulent Newcastle disease virus following challenge of chickens with different titres of serum antibody to the virus.

Virulent Newcastle disease virus (NDV) was isolated from susceptible and immune chickens following intra-ocular challenge with the Essex '70 strain. Challenge virus was isolated from the trachea and cloaca of susceptible birds until they died 7 to 9 days after challenge. This virus was isolated from immunised chickens for up to 14 days after challenge. The duration of excretion was influenced by the prechallenge serum antibody titre to NDV. It persisted longest in chickens with titres of 2(3) to 2(7) and decreased in length and frequency from chickens with titres in the range 2(8) to 2(12). Chickens with pre-challenge titres of 2(3) to 2(5) developed 2- to 3- fold increases in post-challenge titres, whereas those with higher pre-challenge titres had smaller proportional increases in titre. Excretion of virulent virus from immunised birds should be considered in the development of Newcastle disease control programs.

Animals↗

Protective immunity against Newcastle disease: the role of cell-mediated immunity.

The role of cell-mediated immunity (CMI) in protection of birds from Newcastle disease was investigated by two different strategies in which only Newcastle disease virus (NDV)-specific CMI was conveyed without neutralizing antibodies. In the first strategy, selected 3-wk-old specific-pathogen-free (SPF) birds were vaccinated with either live NDV (LNDV), ultraviolet-inactivated NDV (UVNDV), sodium dodecyl sulfate-treated NDV (SDSNDV), or phosphate-buffered saline (PBS) (negative control) by the subcutaneous route. Birds were booster vaccinated 2 wk later and challenged with the velogenic Texas GB strain of NDV 1 wk after booster. All vaccinated birds had specific CMI responses to NDV as measured by a blastogenesis microassay. NDV neutralizing (VN) and hemagglutination inhibition (HI) antibody responses were detected in birds vaccinated with LNDV and UVNDV. However, birds vaccinated with SDSNDV developed antibodies that were detected by western blot analysis but not by the VN or HI test. Protection from challenge was observed only in those birds that had VN or HI antibody response. That is, birds with demonstrable CMI and VN or HI antibody response were protected, whereas birds with demonstrable CMI but no VN or HI antibody response were not protected. In the second strategy, birds from SPF embryos were treated in ovo with cyclophosphamide (CY) to deplete immune cells. The birds were monitored and, at 2 wk of age, were selected for the presence of T-cell activity and the absence of B-cell activity. Birds that had a significant T-cell response, but not a B-cell response, were vaccinated with either LNDV, UVNDV, or PBS at 3 wk of age along with the corresponding CY-untreated control birds. The birds were booster vaccinated at 5 wk of age and were challenged with Texas GB strain of NDV at 6 wk of age. All birds vaccinated with LNDV or UVNDV had a specific CMI response to NDV, VN or HI NDV antibodies were detected in all CY-nontreated vaccinated birds and some of the CY-treated vaccinated birds that were found to have regenerated their B-cell function at 1 wk postbooster. The challenge results clearly revealed that CY-treated birds that had NDV-specific CMI and VN or HI antibody responses to LNDV or UVNDV were protected, as were the CY-nontreated vaccinated birds. However, birds that had NDV-specific CMI response but did not have VN or HI antibodies were not protected from challenge. The results from both strategies indicate that specific CMI to NDV by itself is not protective against virulent NDV challenge. The presence of VN or HI antibodies is necessary in providing protection from Newcastle disease.

Animals↗

[Immunity after newcastle disease in man (author's transl)].

5 patients, in whom Newcastle disease was diagnosed on the basis of a positive haemagglutination inhibition test (HIT) following contact with affected chickens in 1970 were re-examined recently. The ophthalmological findings were negative at follow-up in all cases. The HIT was still positive (1 : 8) in one patient only; no antibodies were detected in the other four patients.

Animals↗

[The transmission of maternal Newcastle disease antibodies in pheasants].

After vaccination of breeding pheasants against Newcastle disease the transmission of antibodies to chicken was investigated by serological methods (hemagglutination inhibition test). The vaccination was carried out about 4 weeks before the start of the laying season. High levels of antibodies were found in egg yolk and blood serum of three days old pheasant chicks. The antibody level dropped at the end of laying season about 10 1/2 weeks after vaccination slightly. Antibodies were found in all of the investigated eggs.

Animals↗