Showing papers on "Newcastle disease published in 1973"

Studies on interferon production and interferon sensitivity of different strains of Newcastle disease virus.

Abstract: Summary Strains of Newcastle disease virus (NDV), which were good or poor inducers of interferon in chick cells, occurred in all virulence groups of this virus. Mesogenic and velogenic strains which killed the embryo rapidly were better interferon inducers in embryonated egg than were the lentogenic strains. Identical and low sensitivities to interferon were shown by an interferon-inducing vaccine strain and a non-inducing and highly virulent strain. Measurements made when various strains were used to infect either normal or interferon-pre-treated cells showed that the absence of interferon production was not due to the inhibitory effect of virus infection on cellular protein synthesis. It is suggested that infective NDV synthesizes two kinds of inhibitory protein during infection. One of these inhibits the synthesis of the interferon protein and in consequence the majority of strains do not induce interferon in chick cells. The second protein is induced mainly by mesogenic and velogenic strains and may be responsible for inhibiting cellular protein synthesis.

The viscerotropic pathotype of Newcastle disease virus.

Abstract: SUMMARY The viscerotropic form of Newcastle disease is defined and the history of the present panzootic of this disease is reviewed. Evidence is presented to support the concept that the viscerotropic form is genetically different from established enzootic forms of Newcastle disease. Ways of differentiating the pathologic forms are described. Transmission of the virus is discussed so as to identify problems of controlling its spread and preventing further introductions.

Separation of the Messenger RNAs of Newcastle Disease Virus by Gel Electrophoresis

Abstract: We have separated the 18-22S putative messenger RNA of Newcastle disease virus into seven species ranging in molecular weight from 0.55 to 1.53 × 106 using sodium dodecyl sulfate-acrylamide-gel electrophoresis at relatively high concentrations of acrylamide and for a relatively long time. Studies of the number and molecular weights of the proteins and the 18-22S RNAs of the virus suggests that these RNAs are in the right molecular weight range to code for the known proteins of Newcastle disease virus. In preliminary studies using this separation technique, we have demonstrated that: (a) there is no difference between the 18-22S RNA made during a normal infection and when genome replication is blocked; and (b) there is a strain-specific difference between the RNAs of Newcastle disease virus-AV and Newcastle disease virus-HP.

Immune responses in mice to tumour challenge after immunization with newcastle disease virus‐infected or X‐irradiated tumour cells or cell fractions

Abstract: Cells of the transplantable ascites tumour sarcoma 37 (S37) have been infected in vitro with Newcastle disease virus (NDV). Infected cells, a virus-containing fraction of such cells, and X-irradiated S37 cells have been found to immunize mice against subsequent tumour challenge. Anti-lymphocyte serum and anti-theta serum interfered with this immune response. The level of humoral anti-tumour antibody did not correlate with immunity. Preimmunization with homologous virus (NDV) prior to inoculation with a virus-containing tumour cell fraction did not in this system enhance the immune response against tumour challenge. The implications of these findings are discussed. Caution is advocated in applying the results of experiments with such animal tumour virus models to the human clinical situation.

Studies on the Cytopathic Effects of Newcastle Disease Virus: the Cytopathogenicity of Strain Herts 33 in five Cell Types

Abstract: Summary The cytopathogenicity and production of Newcastle disease virus (NDV) strain Herts cultivated in chick embryo (CE), baby hamster kidney (BHK-21), HEp-2, MDBK and L929 cells was investigated. Infection at high multiplicities (1000 p.f.u./cell) induced cell fusion in cultures of all cell types within 3 h after infection. Infection at low multiplicities (10 to 20 p.f.u./cell) produced extensive cell fusion in CE, BHK-21, HEp-2 and L929 cultures within 24 h, but MDBK cells failed to fuse. The latter cells failed to show high levels of virus haemagglutinin at the cell surface or accumulation of virus products, but infective virus was released to significantly higher titres than from the cell types which fused. However, infected MDBK showed similar levels of virus-induced cell damage to the plasma membrane, as measured by the release of lactate dehydrogenase, to HEp-2 and L929 cells which were susceptible to fusion. The morphology of the c.p.e. produced by strain Herts in the different cell types is described. The relationship of virus accumulation and virus release to the process of cell fusion is discussed.

Persistent Infection of Cells in Culture by Measles Virus III. Comparison of Virus-Specific RNA Synthesized in Primary and Persistent Infection in HeLa Cells

Abstract: The pattern of actinomycin D-resistant RNA synthesis was examined during primary infection of HeLa cells by virulent Edmonston measles virus and in two HeLa clones persistently infected by the same strain of virus. One of these clones, K11, produces infectious virus of low virulence for HeLa cells, and the other, K11A-HG-1, has thus far failed to yield infectious virus. The patterns of virus-specific RNA synthesized in these three types of infection are qualitatively similar to each other and to the patterns of virus-specific RNA synthesis in other paramyxovirus infections. There were, however, quantitative differences. In addition, virions of the virulent Edmonston strain of measles virus were found to contain high-molecular-weight RNA with a sedimentation constant identical to that of Newcastle disease virus.

RNA-Dependent DNA Polymerase Activity in Preparations of a Mutant of Newcastle Disease Virus Arising from Persistently Infected L Cells

Abstract: RNA-dependent DNA polymerase activity was found in peparations of a mutant of Newcastle disease virus. The enzyme activity was not found in wild-type virus preparations.

Immunologic response of chicks to inactivated Newcastle disease virus.

Abstract: One of the major problems in controlling Newcastle Disease (NDV) is the lack of immune response of young chicks up to 21 days old. Although this age group is very sensitive to infection, maternal antibodies and presumed immunologic immaturity make it difficult to induce an adequate immune response (4,5). An additional problem is variability in the level of maternal antibodies (1,2): when some chicks are still protected by maternal antibodies others are at a high risk of infection because of either a low level or complete loss of maternal antibodies (Zakey-Rones and Levy, unpublished). To investigate this problem without virus multiplication, an inactive vaccine was used. The vaccine used contained an equivalent of 108-3 EID5o of virus prepared by inactivating the NDV, strain Israel (kindly given to us by Dr. A. Kohn, Israel Institute for Biological Research, Nes-Ziona, Israel) with /-propiolactone and mixed with incomplete Freund's adjuvant (6). We had previously found that this dose of antigen stimulates an adequate antibody response in chickens and confers resistance against challenge with a highly virulent strain (Zakay-Rones and Levy, in preparation). Groups of chicks 3-5 days old, the offspring of unimmunized chickens and lacking maternal antibodies, were immunized intramuscularly with inactive oil-adjuvant vaccine. Antibody response was determined by the hemagglutination-inhibition (HI) test (Table 1). Chicks in group 1, completely lacking maternal antibodies, responded to a 108 3 EID5o dose of antigen with high titers of HI antibodies. The antibody titers remained at a high level for as long as 3 months. In group III, in the presence of maternal antibodies, a very low titer of HI antibodies could be detected after

Persistent Newcastle disease virus infection in embryonic chicken tracheal organ cultures.

Abstract: The persistent infection of embryonic chicken tracheal organ cultures with Newcastle disease virus (NDV) is described. Tracheal explants remained morphologically intact and were able to support the replication of NDV for 6 months. Peak titers of released virus occurred at 1 week postinfection, whereas maximal immunofluorescence was not observed until 30 days postinfection. The inoculum titer was not critical, and viral persistence resulted with either of two strains of NDV tested. Serum was not required in the medium for explant viability or to maintain the persistent infection. The presence of a contaminating virus morphologically resembling a leukovirus neither altered the course of infection nor affected the survivability of explants. Although interferon was not detected in the culture medium, persistently infected explants were resistant to heterologous viral challenge, and a similar resistant state could be induced in uninfected explants with exogenous interferon or ultraviolet light-inactivated NDV. No evidence was found to implicate antibody as a regulatory factor in the establishment or maintenance of persistence. The results from electron microscopy and immunofluorescence suggest the cells of the subepithelial connective tissue as the site of NDV persistence.

Increased toxicity of double-stranded ribonucleic acid in virus-infected animals.

Abstract: Virus-infected mice were significantly more susceptible to the toxic effects of double-stranded ribonucleic acid (RNA) than uninfected mice. A dramatic increase in mortality was observed after injection of either synthetic (polyriboinosinic·polyribocytidylic acid) or natural (mycophage) double-stranded RNA in mice infected with Newcastle disease virus (NDV) or vesicular stomatitis virus (VSV). With the exception of endotoxin, interferon inducers other than double-stranded RNA, such as tilorone-hydrochloride and chlorite-oxidized oxyamylose, did not show this increased toxicity in virus-infected animals. The increased susceptibility of virus-infected animals to the toxic effects of double-stranded RNA appears to be related to the levels of interferon induced by the virus infection, either systemically, in the blood stream (after inoculation of NDV), or locally, in the brain (after infection with VSV).

Studies on the cytopathic effects of Newcastle disease virus: RNA synthesis in infected cells.

Abstract: Many viruses, in addition to the induction of c.p.e., produce profound biochemical alterations in the cell, particularly by the inhibition of cellular macromolecular synthesis (for review see Roizman & Spear, 1969). Reeve et al. (1971) have shown that the ability of different Newcastle disease virus (NDV) strains to inhibit cellular protein synthesis is related directly to their virulence for cells in vitro and for eggs and chickens in vivo. Certain NDV strains can also inhibit cellular RNA synthesis, but the relationship of this property to the virulence of the infecting strain is not clear (Wheelock & Tamm, 1961; Scholtissek & Rott, 1965; Wilson, 1968). Moore, Lomniczi & Burke (1972) examined 13 strains of NDV but were unable to establish a relationship between virulence and the inhibition of host cell RNA synthesis. The cell culture techniques and most of the virus strains have been described (Alexander, Reeve & Allan, 1970; Reeve & Poste, 1971).

Vaccination of turkeys against Newcastle disease.

Abstract: Turkeys given primary vaccination with an inactivated Newcastle (ND) vaccine failed to respond satisfactorily in the serumvirus neutralization test and challenge of immunity via the respiratory tract. Revaccination did not effect a satisfactory anamnestic response. LaSota strain Newcastle disease virus (NDV), however, applied by eyedrop or in drinking water, stimulated excellent immunity by the same criteria. Response was unsatisfactory when LaSota NDV was given intramuscularly. Bl-strain NDV given by eyedrop or drinking water induced good immunity but of lower magnitude than from the LaSota strain. Cell-culture ND vaccine resulted in relatively poor protection from infection of the respiratory tract, and the virus-neutralizing antibody titers were relatively low or marginal. The potential use of lentogenic NDV strains in turkey vaccination programs was discussed.

Infectious bronchitis outbreaks in vaccinated poultry in Connecticut.

Abstract: Infectious bronchitis (IB) virus was isolated from a large number of cases of respiratory disease in Connecticut chickens. Eight isolates were all characterized as the JMK strain of IB. Most cases occurred in flocks that were well vaccinated with Massachusetts strain IB vaccine and, where tested, exhibited good virus-neutralizing serum titers. Histopathologic lesions in the trachea in acute cases consisted mainly of epithelial hyperplasia with little or no edema or mononuclear infiltration, a lesion pattern that is described as typical of Newcastle disease (ND). However, no ND infections were found in these cases of IB.

Immunization of Chickens with an Inactivated Oil-Adjuvant Newcastle Disease Virus Vaccine

Abstract: SUMMARY The preparation of an inactivated oil-adjuvant vaccine of Newcastle Disease virus (NDV) using /8-propiolactone (BPL) is described. The method used also caused inactivation of avian sarcoma viruses. Intramuscular or subcutaneous injections in 4-week-old chickens evoked high levels of hemagglutination-inhibiting (HI) antibodies in the serum which persisted over long periods. It also conferred immunity against challenge with 2 X 105 ELD50 of a virulent strain of NDV administered intramuscularly or by contact.

Isolation and identification of myxoviruses from domestic and imported avian species.

Abstract: During the past 15 months a velogenic strain of Newcastle disease virus and an exotic avian influenza-A virus were isolated from accessions received from several areas of the United States. In one instance, both viruses were isolated simultaneously from imported birds on one farm for ornamental birds. The influenza-A virus reacted in the hemagglutination-inhibition test with antisera prepared against the antigens of Chicken/Scotland/'59 and Duck/England/'62 and was possibly disseminated from one source.

Protection of chickens afforded by commercial lentogenic vaccines against challenge exposure to velogenic Newcastle disease virus.

Abstract: Viscerotropic and neurotropic velogenic strains of Newcastle disease virus (NDV) have been isolated during disease outbreaks in the United States since May 1971. These viruses have caused high mortality in vaccinated poultry flocks. In this study, two commercial lentogenic NDV vaccines were shown to afford protection to challenge exposure to velogenic strains suggesting a re-examination of vaccination procedures.

Interference of Mycoplasma gallisepticum with multiplication of Newcastle disease virus in chicken tracheal organ cultures.

Abstract: SUMMARY It is shown that Mycoplasma gallisepticum may interfere with the multiplication of Newcastle disease virus in chickens exposed to ammonia.