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PubMed1978

Noncytopathic mutants of Newcastle disease virus.

We have isolated a novel class of mutants of Newcastle disease virus which are less cytopathic than their virulent parent but are still capable of infectious virus production. Unlike wild-type virus, the mutants did not form plaques after 2 days of incubation; they did, however, make hemadsorbing spots. The mutants range in production of infectious virus from 10 to 200% of that of the wild type. They were less cytopathic in a single cycle of infection by light microscopy, loss of protein from the plate, and inhibition of total protein accumulation. All of the mutants exhibited extended mean embryo death times, a correlate of virulence in the adult animal.

Animals↗
PubMed2005

Mapping of the RNA promoter of Newcastle disease virus.

The RNA promoters of the genome and antigenome of Newcastle disease virus (NDV) were studied by mutational analysis of their 3' terminal ends. Similarly to other paramyxoviruses, NDV RNA replication follows the rule of six, and the genomic and antigenomic promoters require two discontinuous regions: conserved region I (first 18 nucleotides) and conserved region II (nucleotides 73-90). Proper spacing between those regions and the phase of six in region II is critical for efficient RNA promoter activity. As expected, the gene start signal at the 3' end of the NDV genome was required for mRNA transcription, but not for RNA replication. Surprisingly, mutation of the polyadenylation signal in the 5' end did not affect gene expression transcription. Although the conserved region I of NDV (avulavirus) promoter appears to be more similar to that of Sendai virus (SeV) (respirovirus), conserved region II is analogous to that of rubulaviruses.

Cell Line↗
PubMed1975

Methylation of messenger RNA of Newcastle disease virus in vitro by a virion-associated enzyme.

Purified Newcastle disease virus contains an enzyme that incorporates the methyl group from S-adenosyl-L-methionine into RNA synthesized in vitro by the virion-associated RNA polymerase (RNA nucleotidyltransferase). Incorporation of radioactivity from S-adenosyl-L-[methyl-3H]methionine was totally dependent upon RNA synthesis. The methylation reaction was completely inhibited by S-adenosyl-L-homocysteine, suggesting the transfer of only the methyl group of S-adenosyl-methionine to RNA products. Velocity sedimentation and hybridization of the in vitro product RNA indicated that both [3H]methyl and [32P]GMP labels resided in single-stranded 18S RNA molecules which were virus specific. Approximately 1 to 2 methyl groups were incorporated per RNA molecule. DEAE-cellulose chromatography of product RNA after alkaline hydrolysis suggested that the 5' terminus was the site of methylation.

Chromatography, DEAE-Cellulose↗
PubMed1973

Isolation and purification of the envelope proteins of Newcastle disease virus.

A procedure has been developed for the isolation of Newcastle disease virus (NDV) envelope proteins. The two surface glycoproteins and the non-glycosylated membrane protein were solubilized with 2% Triton X-100 and 1 m KCl. Removal of the KCl by dialysis yielded by precipitation a pure preparation of the non-glycosylated membrane protein, which is insoluble in solutions of low ionic strength. The soluble fraction consisting of the two glycoproteins possessed full neuraminidase and hemagglutinating activities. The two glycoproteins could be separated by rate zonal sedimentation in a sucrose gradient containing 1% Triton X-100 and 1 m KCl. Under these conditions, the sedimentation coefficient of the larger glycoprotein, virus protein 1, was 9.3s, and that of the smaller, virus protein 2, was 6.1s. Both hemagglutinating and neuraminidase activities were associated with virus protein 1; virus protein 2 had neither activity. The results suggest that both activities reside on a single NDV glycoprotein. Similar results were obtained previously with another paramyxovirus, simian virus 5. These findings suggest that the association of hemagglutinating and neuraminidase activities with one glycoprotein is a general property of the paramyxovirus group.

Amino Acids↗
PubMedDate not supplied

Competition between nonplaquing and plaquing strains of Newcastle disease virus as affected by temperature.

If lentogenic (nonplaquing) strains of Newcastle disease virus were inoculated into a monolayer of chicken embryo fibroblasts before velogenic (plaquing) strains, the plaquing of the latter were inhibited partially or completely. An interval of 22 hours between the two inoculations gave greater inhibition than did 1 hour. In general, lentogenic strains grew better at 37 C (inhibited plaquing more effectively) than at 42 C. Enzootic velogenic strains that produce a neurotropic form of the disease in chickens were inhibited more than were exotic velogenic strains that produce a viscerotropic form. The lentogenic strains differed markedly in ability to interfere with velogenic strains.

Animals↗
PubMed1987

Rat leukocyte interferons: production of an acid-labile interferon after induction with Newcastle disease virus.

Rat leukocytes produce three interferon species after infection with Newcastle disease virus. Two of the three interferon species (22-24,000 and 30,000 daltons) were acid and heat stable, protected rat and mouse cells from virus-mediated cytopathic effect (CPE), and were neutralized by antisera to mouse L-cell (alpha/beta) interferon. The third, 30,000-dalton interferon species was heat and acid labile; protected rat, mouse, human, and bovine cells from virus-mediated CPE; and was neutralized by antisera to mouse L-cell interferon and human leukocyte interferon. Thus, the rat leukocyte interferon system is similar to the human system in the kinetics of interferon production, the production of multiple interferons, heterologous antiviral activity, molecular weight, and in the production of an acid-labile species. The rat leukocyte interferon system therefore represents an important model for examining the normal production and action of acid-labile interferons and their possible role in the regulation of leukocyte function and cellular differentiation.

Animals↗
PubMedDate not supplied

The interaction between Newcastle disease virus and Escherichia coli endotoxin in chickens.

The interaction between Newcastle disease virus (NDV) and Escherichia coli endotoxin was studied in cell cultures, embryonated chicken eggs, and 8-wk-old chickens. These interactions were evaluated according to the induction of specific or nonspecific resistance in the host system and the virus titer produced in both chicken embryos and chickens. The endotoxin of E. coli induced a decrease in the size of the bursa of Fabricius in live chickens. Escherichia coli endotoxin given intravenously induced plasma antiviral activity in chickens that was interpreted to be interferon, as detected in a vesicular stomatitis virus plaque reduction assay. Endotoxin failed to produced toxic effects in the chicken embryo fibroblasts (CEFs) or to result in any antiviral effect because no change was noted in the number of NDV plaques formed in CEF cultures. When endotoxin was given 3 days before NDV exposure in chickens, the virus titers were significantly (P < 0.05) decreased from a peak of 10(2) to 10(0.18), 10(2.5) to 10(0.18), and 10(2.5) to 0 in the spleens, lungs, and kidneys, respectively, at 72 hr post-NDV inoculation. When endotoxin was given 24 hr after NDV inoculation, the NDV titer significantly (P < 0.05) increased from 10(2.0) to 10(3.5), 10(2.5) to 10(6.5), 10(2.5) to 10(4.5), 0 to 10(2.5) in the spleen, lungs, kidneys, and liver, respectively, at 72 hr after NDV inoculation. In chicken sera, hemagglutination inhibition (HI) titer to NDV was significantly (P < 0.05) enhanced from 1164 to 3127 when endotoxin was given prior to virus inoculation. However, there was a decrease in HI to NDV from 1164 to 727 without a significant difference in chicken sera when NDV was given prior to endotoxin inoculation.

Animals↗
PubMedDate not supplied

Characterization of a velogenic Newcastle disease virus isolated from broilers in Saudi Arabia.

A highly virulent Newcastle disease virus (SA84) was isolated from a large broiler operation in Saudi Arabia. The mean death time of chicken embryos given the minimum lethal dose, the pathogenicity of the isolate for 8-week-old chickens, the plaque characteristics, and the intracerebral pathogenicity index indicated that the isolate is of the viscerotropic velogenic pathotype.

Animals↗
PubMed1987

Detergent-treated Newcastle disease virus as an agar gel precipitin test antigen.

A soluble Newcastle disease virus (NDV) agar gel precipitin (AGP) antigen was prepared by treating 100-fold concentrated NDV with a nonionic detergent. Virus concentration prior to detergent treatment was best accomplished by ultracentrifugation or by a simple, less expensive, and more practical method involving acid (HCl) precipitation of NDV. Virus concentrated by polyethylene glycol precipitation was found to have a low antigen titer and was not considered suitable as an AGP antigen. Antigens derived from the LaSota, Roakin, and Texas GB strains formed at least two lines of identity in the AGP test as early as 24 hr after inoculation of the agar gels. Virus used for AGP antigen production could be grown in chicken embryos from an NDV-immune as well as susceptible breeder flock. The NDV AGP antigen was found to be stable after 20 consecutive freezing and thawing cycles and storage at -20 C or 4 C for at least 6 months. Detergent-treated NDV was used as an AGP test antigen to determine serum antibody responses of chickens following infection and vaccination. Hemagglutination-inhibition, virus neutralization, and enzyme-linked immunosorbent assay antibody production was also evaluated for comparative purposes. The AGP test was found to be useful as an aid in diagnosing field infections and assessing inactivated virus vaccination responses. These purposes were achieved by demonstrating an increase in the number of AGP positive chickens between preinfection and postinfection or vaccination bleedings. The ease of performance and low cost of the AGP test favors its use for screening large numbers of serum samples, perhaps in conjunction with a quantitative serological test.(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗
PubMed1970

Thermal inactivation of Newcastle disease virus.

The rate of destruction of hemagglutinins and infectivity of Newcastle disease virus was determined over a temperature range of 37.8 to 60 C. From the calculated values of deltaH and deltaS, it was concluded that inactivation of the hemagglutinating activity and viral infectivity was due to protein denaturation.

Animals↗
PubMed1998

Potentially virulent Newcastle disease viruses are maintained in migratory waterfowl populations.

Forty-seven Newcastle disease virus (NDV) strains isolated from fecal samples of waterfowls in Alaska and Siberia from 1991 to 1996 were analyzed for their virulence. None of the viruses formed plaques on MDBK cells in the absence of trypsin. Of these, 29 strains showed virulent character by the mean death time with the minimum lethal dose in chicken embryos comparable to velogenic NDV strains. Of the 29 strains, 11 were sequenced for their fusion protein (F) gene. The results showed that 5 of them contained a pair of dibasic amino acids at the cleavage site of the F, which is of a virulent type. The present results suggest that potentially virulent strains of NDV are maintained in migratory waterfowl populations in nature, and that some of those may be transmitted to domestic poultry and acquire pathogenicity during passages in chicken population.

Alaska↗
PubMed1978

Viral proliferation patterns of a velogenic (VLT), a mesogenic (Komarov), and a lentogenic (F) strain of Newcastle disease virus.

A highly pathogenic and two avirulent vaccine strains of Newcastle disease virus were investigated quantitatively for their proliferation in various tissues of experimentally infected SPF chickens. Virulent strain VLT multiplied extensively in all the tested tissues whereas a mesogenic strain (K) was not detected in the brain during the period of observations. A lentogenic strain (F) was only detected in moderate quantities in trachea. The development of antibodies seemed to correlate with the disappearance of the two avirulent strains from the tissues.

Animals↗
PubMed1987

Antigenic variation of Newcastle disease viruses isolated from wild ducks in Japan.

Nineteen strains of Newcastle disease virus (NDV) isolated from wild ducks in Japan were placed into 4 distinct antigenic groups on the basis of their reactivities to 8 monoclonal antibodies against the HN molecule of NDV in hemagglutination inhibition tests. The NDV strains of duck origin were antigenically distinct from NDV-B1 and NDV-Miyadera originated from chickens, and varied in their virulence to chicken embryos. No apparent correlation was found between the antigenicity of the HN molecule and virulence.

Animals↗
PubMed1991

Reconstituted Newcastle disease virus envelopes as a split vaccine.

Isolated envelope proteins of Newcastle disease virus (NDV) were inserted into the lipid bilayer of artificial vesicles to create a viral envelope-like structure. The structure-containing viral antigens at high density elicited a strong immune response, in contrast to purified viral proteins. The artificial envelopes or immunosomes possessed several advantageous properties when used as vaccines. They elicited a faster response and the immunity lasted longer in animals treated with these vesicles than in controls vaccinated with envelope proteins in combination with traditional adjuvants. A further useful feature of the artificial envelopes is that no inflammatory lesions develop at the site of their injection.

Animals↗