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PubMed2005

Assessment of newcastle disease vaccination of houbara bustard breeders (Chlamydotis undulata undulata).

The houbara bustard (Chlamydotis undulata undulata) is endangered in North Africa. Through a captive-breeding program established in Morocco by The Emirates Center for Wildlife Propagation, wild populations are being supplemented by the releasing of captive-reared birds. Newcastle disease, which is caused by Newcastle disease virus (NDV; Avian paramyxovirus type 1), can infect houbara bustards and is a significant threat through contact with backyard poultry and possibly wild birds. Three vaccination schedules for Newcastle disease were evaluated by serologic monitoring to assess the efficiency and safety of various types of vaccines (live vs. inactivated), vaccine strains (Hitchner B1 and Clone 30), and administration routes (intranasal vs. injection). We evaluated antibody titers in 211 adult houbara bustards for 10 mo. Antibody titers to NDV in both sera and egg yolks were monitored by hemagglutination inhibition test. The inactivated vaccine provided a high, homogeneous, and durable serologic response in breeders; titers were higher than log2 11 after 4 wk and remained higher than log2 7 after 10 mo. The response to the two live vaccines was similar, and antibody titers did not exceed log2 6 at sero-conversion. Maternally derived antibodies were efficiently transmitted in vitellus, further confirming that offspring of females hyperimmunized with the inactivated vaccine received high titers of maternal antibodies.

Animals↗
PubMed1981

[Properties of local velogenic strains of Newcastle disease virus in poultry].

Studies were carried out on four strains of the Newcastle disease virus, isolated in Bulgaria and referred, as typed by the routinely used methods, to the velogenic group. The strains proved to be hemagglutinin - thermostable. Two of the local virus strains (Rosa and Toutrakan) belonged to the velogenic-neurotropic pathogenic type, and two (Bregovo and Haskovo) - to the velogenic - viscerotropic pathogenic one. All four strains were slowly eluated from chicken erythrocytes. Full immunologic similarity was established between these strains by means of the live vaccines used in this country for the specific prevention of Newcastle disease, produced with the lentogenic strains Hitchner B1 and La Sota and the mesogenic Komarov.

Animals↗
PubMed1992

Pathogenicity of two strains of Newcastle disease virus in the grey-breasted helmet guinea fowl.

Thirty-five 6-week-old guinea fowl keets, seronegative for maternal antibodies to Newcastle disease virus, were infected with Herts strain (33/56) and Kumarov strain of Newcastle disease virus intramucularly (IM) or intranasally (IN). Clinical signs were first noticed four days post infection (PI) in the group infected IM but five days PI in the group infected IN with Herts strain of Newcastle disease virus. These clinical signs were similar in both groups and included anorexia, droopiness, huddling together, greenish diarrhoea and marked cachexia. Prominent nervous signs, including spasms of the head and neck, were observed in groups infected with Herts strain. The major gross lesions observed were emaciation with prominent keel bone, empty intestinal tract and distended gall bladder in most keets. The histological lesions were characterised by meningoencephalitis, necrosis and loss of lymphocytes from splenic and lymphoid aggregates. There was muscular degeneration and necrosis in the gizzard and mild pulmonary congestion and oedema in some keets. Neither gross or microscopic lesions were observed in keets that had received the Kumarov strain.

Animals↗
PubMed1978

[Comparative studies of methods for the detection of immune carriers of the Newcastle disease virus in poultry].

Mass prophylactic vaccinations have radically chaugned the clinical syndrome, pathogenesis, and morphological picture of the Newcastle disease: clinically it is manifested with respiratory troubles, and morphologically--with tracheitis. The method for isolating the virus on chick embryos from immune birds have proved undependable: the higher the immunity of birds, the lower the probability of virus isolation. Following the vaccination of birds after the adopted prophylactic programme and at the three-fold vaccination with a lentogenic La Sota strain and four-fold vaccination with a mesogenic Komarov strain precipitating antibodies have been detected in single serum samples only. In the presence of respiratory troubles in immune birds the rise of antiheamagglutination titers and the mass manifestation of precipitating antibodies in the blood serum is said to be an indication of the presence of a field of velogenic virus, while HI and AGPT are suitable methods for the detection of immune carriers of Newcastle disease. These can be used also for the differential diagnosis of the latent forms of infectious bronchitis, infectious laryngotracheitis, the diphtheroid form of pox, and CRD. In order to restrict and do away with the velogenic field strains of the Newcastle disease virus a suggestion is made to kill all birds that have shown respiratory troubles and positive results in virologic and serologic examinations through HI and AGPT.

Animals↗
PubMed1984

[Newcastle disease virus carrier state after aerosol vaccination against the disease in chickens of various ages].

Studied was the carrier status with the Newcastle disease virus in experiments with a total of 665 birds at the age of 10 days, one month, and two months following an aerosol vaccination with a La Sota strain vaccine as well as the possibility to isolate the velogenic strain Texas GB after control infection of 10-day-old and one-month-old birds. Established was a short-term carrier status with the La Sota strain in the organs of birds up to the 6th-9th day following the aerosol vaccination. In an experiment with month-old birds originating from parental flocks immunized against Newcastle disease the La Sota virus was isolated also from the brain up to the sixth day. The resistance of birds to the infection was demonstrated at the aerosol immunization of 10-day-old and month-old- birds followed by challenging the birds with high doses of the velogenic virus strain Texas GB.

Aerosols↗
PubMedDate not supplied

Effect of infectious bursal agent on the response of chickens to Newcastle disease and Marek's disease vaccination.

White Leghorn chickens raised from one day old in an environment contaminated by the infectious bursal agent (IBA) had lower geometric mean titers (GMT) as measured by the hemagglutination-inhibition (HI) test to the Newcastle disease virus (NDV), than control Leghorns reared in an uncontaminated environment. Immunosuppression, defined as a reduction in GMT, was most pronounced at 35-56 days old for Leghorns vaccinated with NDV at 1 and 28 days or at 28 days. In a separate trial with broilers, immunosuppression was similar at 42-56 days old. This study also demonstrated that IBA infection in chickens increased susceptibility to Marek's disease (MD). The unvaccinated control chickens infected with IBA averaged 56.3% MD lesions, whereas unvaccinated controls not exposed to IBA averaged only 18.1% macroscopic lesions. It was also found that 20.7% of the HVT-vaccinated chickens exposed to IBA had gross MD lesions, whereas those HVT-vaccinated chickens reared in an environment free of IBA had 2.99% gross MD lesions.

Animals↗
PubMedDate not supplied

Antibody detection in matched chicken sera and egg-yolk samples by commercial enzyme-linked immunosorbent assay kits for Newcastle disease virus, infectious bronchitis virus, infectious bursal disease virus, and avian reovirus.

ELISA kits have been used to detect antibody in egg yolk. The major advantage eggs offer over blood samples is the ability to collect samples without compromising flock biosecurity. A disadvantage to using egg yolk over sera concerns the method of preparing yolk for antibody testing. The technique used in this study involved a simple dilution method with no mixing or extraction. To determine the adequacy of yolk samples to replace serum samples, a serum sample and the first six eggs were obtained from each of 50 commercial leghorn hens. Mean titers were consistently larger for serum than for yolk, but the size of the difference varied with the virus. The variation of mean egg titer was comparable to that of the serum titer. Correlations between a hen's serum titer and the mean titer from hen eggs were only moderate, ranging from 0.35 to 0.85 across viruses and systems. The ability to predict the serum titer of a single hen by the mean titer from hen eggs may be inadequate.

Animals↗
PubMed1981

[Comparison of the thermostability of Newcastle disease virus strains isolated in Slovakia].

Reference strains of Newcastle disease virus of different virulence (two lentogenic, two mesogenic and three velogenic), isolated in Czechoslovakia and other countries, were compared with 11 field strains isolated in Slovakia in 1973, 1977, 1979 and 1980 as to the stability of their infectivity for cell cultures and as to their hemagglutination activity at a temperature of 56 degrees C for 120 minutes. The inactivation curves indicate that ten strains belong to the group of velogenic viruses and one of them is lentogenic. Although the data on hemagglutinin thermostability and infectivity do not suffice to characterize the virus strain, it is possible, by comparing the inactivation curves determined by the described method, to differentiate the field strains of Newcastle disease virus as lentogenic, mesogenic and velogenic. Some instability of the relationship between the thermostability and virulence of the virus is ascribed to the heterogeneity of the virus population.

Animals↗
PubMed1985

Intracellular processing of the Newcastle disease virus fusion glycoprotein.

The fusion glycoprotein (Fo) of Newcastle disease virus is cleaved at an intracellular site (Nagai et al., Virology 69:523-538, 1976) into F1 and F2. This result was confirmed by comparing the transit time of the fusion protein to the cell surface with the time course of cleavage of Fo. The time required for cleavage of half of the pulse-labeled Fo protein is ca. 40 min faster than the half time of the transit of the fusion protein to the cell surface. To determine the cell compartment in which cleavage occurs, use was made of inhibitors which block glycoprotein migration at specific points and posttranslational modifications known to occur in specific cell membranes. Cleavage of Fo is inhibited by carbonyl cyanide m-chlorophenylhydrazone; thus, cleavage does not occur in the rough endoplasmic reticulum. Monensin blocks the incorporation of Newcastle disease virus glycoproteins into virions and blocks the cleavage of the fusion glycoprotein. However, Fo cannot be radioactively labeled with [3H] fucose, whereas F1 is readily labeled. These results argue that cleavage occurs in the trans Golgi membranes or in a cell compartment occupied by glycoproteins quite soon after their transit through the trans Golgi membranes. The implications of the results presented for the transit times of the fusion protein between subcellular organelles are discussed.

Animals↗
PubMed2004

Pathogenesis of conjunctivitis caused by Newcastle disease viruses in specific-pathogen-free chickens.

The pathogenesis of conjunctivitis caused by Newcastle disease viruses (NDVs) was investigated in 3-week-old specific-pathogen-free chickens. The chickens were inoculated intramuscularly, by eye drop or intranasally, with 10(7) plaque forming units of viscerotropic velogenic Newcastle disease virus (VVNDV), mesogenic NDV or lentogenic NDV. Macroscopically, lower palpebral conjunctivae appeared red with oedematous swelling in chickens inoculated with VVNDV. Histologically, mild lesions were focal hyperplasia of the conjunctival epithelial cells with cellular infiltration in the lamina propria of the conjunctivae in the chickens inoculated with VVNDV. Moderate lesions were vascular necrosis with congestion and haemorrhages, hyperplasia of conjunctival epithelial cells, and oedema and cellular infiltration in the lamina propria of the conjunctivae. Fibrin thrombi were observed in the capillaries of the lamina propria. In marked lesions, the whole conjunctiva was affected with more severe and extensive lesions. The mesogenic and lentogenic NDV strains induced no gross conjunctival lesions, but induced mild conjunctivitis without vascular necrosis.

Animals↗