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Lipoprotein inhibitor of Newcastle disease virus from chicken lung.

A lipoprotein inhibitor of Newcastle disease virus was obtained from chicken lung tissue by means of dilute alkaline extraction procedures. The inhibitor was further purified by ammonium sulfate fractionation, isoelectric precipitation, and density gradient centrifugation. The purified lipoprotein inhibited active Newcastle disease virus hemagglutination at a concentration of 2.0 mug/ml which represented a 30-fold purification over the original extract. Infection of chicken embryo fibroblasts by Newcastle disease virus was also inhibited by the purified lipoprotein, the degree of inhibition depending upon the inhibitor-to-virus ratio. Chemical analysis of the purified inhibitor provided a composition of 72% lipid, 26% protein, and 3% carbohydrate, although some compositional variation was observed from one preparation to another. The chloroform-soluble lipids were shown to contain 40 to 50% phospholipid and 10 to 20% cholesterol; of the fatty acids recovered from the saponified lipoprotein, 39% was palmitic, 22% oleic, and 17% stearic. Careful analyses of large quantities of the inhibitor revealed a small (0.84%) but significant content of sialic acid. Removal of sialic acid from the lipoprotein by means of digestion with neuraminidase produced a sharp diminution in inhibitory properties. A delipidized form of the inhibitor was obtained by ether extraction, and this material produced a single broad band of precipitate in gel immunodiffusion tests.

Animals↗

Characterization of Newcastle disease virus (avian paramyxovirus-1) isolated from pigeons.

Newcastle disease virus (avian paramyxovirus-1) was isolated from pigeons in 12 states between May 1984 and December 1985. One of the isolates was from a feral pigeon; the remainder were from privately owned pigeon lofts. Use of monoclonal antibodies showed seven of the eight isolates tested to be indistinguishable from the 1982 and 1983 Great Britain and European isolates. Clinical signs were paralysis, torticollis, tremors, incoordination, and death. Pigeons inoculated with the paramyxovirus-1 isolates intravenously or intramuscularly developed clinical disease identical to that described for natural infection; however, only one pigeon inoculated intranasally developed clinical signs. The mean death time for inoculated pigeons was 9.5 days, with a range of 4 to 25. Virus was shed for up to 20 days. Primary lesions observed on necropsy were gastroenterocolitis and pancreatic necrosis. Chickens experimentally infected by the cloacal, intranasal, or caudal thoracic air-sac route remained healthy. However, the intracerebral pathogenicity index (ICPI) in day-old chickens was similar to that observed with velogenic Newcastle disease virus isolates. Four of six isolates inoculated intravenously into 6-week-old chickens induced neurotropic disease.

Animals↗

Antigenetically unusual Newcastle disease virus from racing pigeons in India.

Newcastle disease virus isolated from an outbreak in racing pigeons in India was found to be velogenic, based on the mean time to death in 10-day-old embryonated hen's eggs, the intravenous pathogenicity index in 6-week-old chickens and the pathogenesis in chickens and pigeons. The virus induced disease in chickens without prior adaptation in chickens. The virus was antigenically unusual since it could not be grouped with the available panel of monoclonal antibodies at the World Reference Laboratory for Newcastle disease, UK. However, commercially available lentogenic and mesogenic vaccines provided 100% protection to chickens against this antigenically unusual NDV.

Animals↗

Conditional dependence of fusion from within and other cell membrane alterations by Newcastle disease virus.

Fusion from within (FFWI) by Newcastle disease virus occurs optimally in medium maintained at pH 8.2, whereas fusion from without is relatively insensitive to the pH of the medium in the range of 7.0 to 8.3. The pH-sensitive events in FFWI take place in the synthesis of the hypothetical fusion factor rather than in the response to it. pH pulse and pH shift experiments have localized the pH-sensitive events between 4 and 6.5 h postinfection (a period of synthesis of proteins required for FFWI), but before the fusion process. The pH sensitivity is not due to a pH-sensitive interference phenomenon. Virus production and the appearance of hemadsorbing cell surfaces are also pH sensitive, but for these functions the pH optima depend upon the virus strains tested. The independence of FFWI, hemadsorption, and virus production is discussed. Also discussed are the possible roles of virus-specific proteins in the fusion process.

Animals↗

Influence of viral envelope on Newcastle disease virus infection.

The adsorption characteristics of Newcastle disease virus (NDV) propagated in chicken cells (NDV-C) and in human cells (NDV-H) were examined. Adsorption experiments performed at different temperatures indicated that virus propagated in a particular cell infected that cell type more readily than did virus propagated in a different host. For example, NDV-C was more efficient in initiating infection of chicken cells at 22 C than was NDV-H; the reverse was true when human cells were employed. The results indicate that infection of susceptible cells by NDV is influenced by the host cell in which the virus was propagated. The data also suggest that NDV may be useful in studies on homologous and heterologous membrane-membrane interactions.

Animals↗

[Antigenic differences in the glycoproteins of the Newcastle disease virus].

The two glucoproteins of the Newcastle disease virus - hemagglutinin-neuraminidase (HN) and F-protein - were isolated in a pure state from two strains of the virus: the La Sota apathogenic strain and the Roussev strain pathogenic for birds. It was found that the large HN glucoprotein of each of the strains was not identical antigenically with the F-protein. These seemed to be partial antigenic relatedness between the HN of the two strains. On the other hand, the F-proteins of the strains were identical.

Antigens, Viral↗

Genetic relationships among lentogenic strains of Newcastle disease virus.

Purified RNA from five lentogenic Newcastle disease virus (NDV) strains (B1, England-F, Nebraska, Queensland V4, and Ulster) was subjected to oligonucleotide fingerprinting analysis. This technique could resolve over 100 oligonucleotides per virus strain, of which 50 to 80 were unique. Although the fingerprints generated from these viral RNAs exhibited similar distribution patterns of non-unique RNA fragments, all could be distinguished from one another on the basis of the migration of unique RNA fragments. It is concluded that oligonucleotide mapping is a useful method of unambiguously identifying individual lentogenic strains of NDV and that this technique may serve as a means of characterizing highly pathogenic NDV isolates.

Newcastle disease virus↗

Pathotyping of Newcastle disease virus isolates from pet birds.

Four Newcastle disease virus (NDV) isolates obtained from a pigeon, lory, parrot, and love bird were subjected to biological and molecular characterization. All the isolates were identified as velogenic with intracerebral pathogenicity indices (ICPI) of 1.9-2.0. All the isolates had a 112RRQKRF117 motif in the fusion protein cleavage site (FPCS), typical for pathogenic NDV. Phylogenetic analysis placed the isolates along with a velogenic Indian isolate of Cl group recovered during 1987.

Animals↗

[Newcastle disease in Algeria. Study of the pathogenic properties of Newcastle disease virus strains isolated in Algeria].

The Newcastle disease in Algeria: Study of pathogenic properties of the Newcastle disease viral strains isolated in Algeria. The study of pathogenic characters of 14 strains of Newcastle disease virus isolated from 1972 to 1982 was carried out: The following testS were realized: the mean lethal time for the chicken embryo, the pathogenic power index by intravenous way, the pathogenic power index by intracerebral way, the hemagglutination spectrum and the thermal stability of the hemagglutination. In short we can say that these isolated 14 strains are fast-growing.

Algeria↗

Development of a cell culture method for quantal assay of strain I-2 of Newcastle disease virus.

Repeated titrations of strains of Newcastle disease virus (NDV) are more conveniently undertaken in cell cultures rather than in embryonated eggs. This is relatively easy with mesogenic and velogenic strains that are cytopathic to various cell lines, but is difficult with avirulent Australian isolates that are poorly cytopathic. Strain V4 for example has been shown to be pathogenic iin vitro only to of chicken embryo liver cells. Strain I-2 was reported to produce cytopathic effect (CPE) on chicken embryo kidney (CEK) cells. The present studies confirmed this observation and developed a quantal assay. CEK cells infected with strain I-2 developed CPE characterized by degeneration, rounding, granularity and vacuolation, and the formation of synctia. End points were readily established by microscopic examination of fixed and stained cells. In virus infectivity studies on strain I-2, where multiple titrations are required and where large numbers of samples are used, titration using CEK cell grown in microtitre plates is recommended. Such studies may not be feasible in embryonated eggs.

Animals↗

Relation of interferon production to the limited replication of Newcastle disease virus in L cells.

Growth of Newcastle disease virus (NDV) in L cells, where the virus undergoes limited replication, has been compared to that in fully permissive BHK-21 host cells. The synthesis of viral proteins and the production of infectious progeny were found to occur normally at early times of infection in L cells. However, the subsequent amplification of viral protein synthesis did not take place and instead of infectious virions, non-infectious haemagglutinin was the predominant product. This shift of replication pattern from complete to incomplete virus production seemed to be temporally related to the appearance and accumulation of interferon (IFN) in the system. The addition of specific antiserum against mouse IFN to the infected L cell cultures was able to circumvent such restriction of virus growth. In the presence of the antiserum, synthesis of viral proteins was found to progress normally, with the production of a high amount of infectious progeny comparable to that of the permissive system. These results suggest that the limited replication of NDV in L cells may be due to interference by the endogenously produced IFN during the course of infection.

Animals↗

Pathogenic properties of Newcastle disease virus isolates in the Sudan.

Six Newcastle disease virus (NDV) isolates were obtained from disease outbreaks on different poultry farms in the Sudan between 1988 and 1991. The pathogenic properties of these isolates were studied in comparison to those of strain Herts 33/56. All the isolates were similar in that they killed chicken embryos quickly, in mean death time (MDT) and embryo lethal dose 50 per cent (ELD50), had higher intracerebral pathogenicity indices (ICPI), and produced viscerotropic lesions in the infected chickens. The field isolates had the characteristics of the velogenic viscerotopic strains of NDV. The pathogenesis of infection caused by one of the isolates was studied. The virus was first detected in different organs and in oral and cloacal swabs on the third day after infection.

Animals↗

Velogenic viscerotropic Newcastle disease virus strains in Morocco.

Isolates of Newcastle disease virus (NDV) in Morocco were characterized as velogenic. Two isolates were from tracheal swabs taken at a Moroccan live poultry market, and four isolates were from field cases. Infection of 8-week-old chickens showed that these isolates and previously characterized Moroccan isolates were of the viscerotropic pathotype. Based on hemagglutinin thermostability and the capacity to agglutinate equine erythrocytes, the Moroccan velogenic viscerotropic NDV isolates were classified as belonging to at least three distinct strains.

Animals↗

Newcastle disease virus antigens and strain variations.

Study of antigenic differences among strains of Newcastle disease virus is complicated by the presence in most field isolates and strains of several genetically distinct plaque populations, and by differences in avidity (reactions to antibody) among Newcastle disease viruses. Kinetic neutralization tests were used to demonstrate antigenic differences among 3 plaque clones of velogenic viscerotropic Newcastle disease viruses recently isolated from 3 avian species. The 3 viruses could be distinguished on the basis of plaque structure and hemagglutinin and neuraminidase activity. Antigenic differences among these viruses distinguished them from older, well characterized Newcastle disease viruses.

Animals↗

Gene with quantitative effect on circulating interferon induced by Newcastle disease virus.

Circulating interferon production, induced by Newcastle disease virus, is about seven times higher in C(57) Black mice than i Balb/c/Gif mice. A Mendelian analysis was carried out and circulating interferon production was measured in reciprocal F(1) hybrids, in the F(2) generation, in progeny of backcrosses of F(1) hybrids to either parent strain, and in second backcross progeny. The results indicate that a single, partly dominant, autosomal factor is responsible for the difference in circulating interferon production between both parent strains.

Animals↗