Showing papers on "Newcastle disease published in 1971"

Studies on the cytopathogenicity of Newcastle disease virus: relation between virulence, polykaryocytosis and plaque size.

Abstract: Summary The cytopathic effects produced by seven strains of Newcastle disease virus grown in chick embryo cell culture were examined. The principal form of cytopathic effect involved the formation of multinucleate cells (polykaryocytes) by cell fusion. The capacity of the different Newcastle disease virus strains to induce cell fusion was related directly to their virulence for chicks and fertile eggs. The virulent (velogenic) strains herts, warwick and texas produced significantly greater polykaryocytosis than the mesogenic strain beaudette c which, in turn, produced greater polykaryocytosis than the avirulent (lentogenic) vaccine strain f. The lentogenic strains queensland and ulster failed to produce detectable cytopathic effects. Distinct morphological differences were noted in the polykaryocytes produced by the different strains. The ability to form plaques and plaque size in chick embryo monolayers was also related to the virulence of the virus strains.

Some properties of an avirulent Newcastle disease virus.

Abstract: Newcastle disease virus was isolated from healthy birds using chick kidney cultures. The virus strain involved was exceptionally attenuated in character and appeared to be transmitted by the enteric route. It caused no clinical illness even in day old chicks and did not regularly kill embryonated eggs. The virus is relatively thermostable and its haemagglutinin is exceptionally stable at 56‡ C. This easily observed property may be useful in genetic studies of the virus.

The Structure and Assembly of Influenza and Parainfluenza Viruses

Abstract: Publisher Summary The name myxovirus was originally proposed for a group of viruses that then included influenza, mumps, and Newcastle disease viruses. These viruses had in common an affinity for certain mucins and physical and biological properties such as the ability to adsorb to red blood cells of chickens and various other species, causing hemagglutination. The viruses also possess an enzyme, neuraminidase that cleaves neuraminic acid from mucoproteins. With increasing knowledge of the structure and replication of these viruses, it has become apparent that they fall into two groups with distinct properties. The members of both the influenza and parainfluenza virus groups are found in a variety of vertebrate species. Many of these viruses infect the respiratory tract, although avian influenza viruses and several of the parainfluenza viruses cause severe generalized diseases. This chapter describes the structure of influenza viruses, morphology of influenza and parainfluenza viruses, and the chemical composition of the influenza virion.

Binding of ribonucleic acids to the RNP-antigen protein of influenza viruses.

Abstract: Summary Influenza virus plus and minus strand RNA complexed with RNP-antigen protein quite efficiently, while double-stranded virus RNA was not significantly bound. Sindbis and Newcastle disease virus RNA attached to a much lower degree. A small AMP-rich RNA fraction of uninfected cells also formed a complex with the virus RNP-antigen protein.

Studies on the cytopathic effects of Newcastle disease virus: metabolic requirements.

Abstract: Summary Nine strains of Newcastle disease virus were examined for their ability to inhibit cellular protein synthesis and to cause cell fusion. Inhibition of cellular protein synthesis was confined to infection with virulent strains (herts, warwick, texas, ‘h’, field pheasant) and the mesogenic strain beaudette c. No inhibition of synthesis was recorded with avirulent strains (ulster, f, queensland). Inhibition of cellular protein synthesis required virus protein synthesis within 3 hr of infection and could be inhibited by parafluorophenylalanine and Congo red. Cell fusion and haemadsorption by the various Newcastle disease virus strains also required virus-induced protein synthesis and were inhibited by cycloheximide, parafluorophenylalanine and Congo red. However, neither virus-induced inhibition of cellular protein synthesis nor cell fusion required new virus RNA synthesis, since azauridine did not affect these processes. The importance of virus-induced proteins in the inhibition of protein synthesis and cell fusion is discussed.

The problem of Newcastle disease.

Abstract: Newcastle disease, the predominant form of fowl pest in Britain, can only be effectively controlled if improvements in vaccines and methods of administration are coupled with better farm hygiene.

Virus RNA and protein synthesis in cells infected with different strains of Newcastle disease virus.

Abstract: Summary The virus RNAs and proteins synthesized in chick embryo cells infected with different strains of Newcastle disease virus have been characterized by polyacrylamide gel electrophoresis. By comparison of the rates of electrophoretic mobility of virus RNA with those of RNA molecules of known molecular weight, the molecular weights were estimated to be 4.8 × 106 for the virus particle RNA and 2.5 × 106, 1.1 × 106 and 0.4 to 0.7 × 106 for the RNA molecules synthesized in infected cells, the latter being heterogeneous. Synthesis of a number of virus particle proteins was readily detected.

Local Immunologic Response to Immunization with Inactivated Newcastle Disease Virus

Abstract: Chickens were immunized with Newcastle disease virus inactivated by β propriolactone. The antigen was administered by the intramuscular or intranasal route, and the appearance of HI antibodies in the serum and lungs was followed. Local secretory antibodies in the lung were found only as a consequence of intranasal immunization, whereas serum antibodies were found after administration of antigen by either route.

Reactions of human sera to avian adenoviruses and Newcastle disease virus.

Abstract: The sera of two human populations were examined for antiviral reactions to avian adenoviruses and to Newcastle disease virus (NDV). Group I had close contact with poultry; Group II had limited association. None of the sera reacted with the avian adenoviruses used. Sera of Group I individuals had a high frequency of NDV hemagglutinin inhibitory (HI) activity; Group II sera showed no such reactions. Sera of both groups showed a low frequency of reactors having NDV neutralizing antibody. Neutralizing activity could not be related to HI activity of the sera. The HI activity observed was apparently not due to cross reactions with mumps antibody.

Methods of isolating six mutant classes from the Hickman strain of Newcastle disease virus.

Abstract: Six plaque-type mutants, two of which are found at low frequency, were isolated from the Hickman strain of Newcastle disease virus. Characterization of these mutants revealed great differences in pathogenicity for chickens and chicken embryos and in the nature of the hemagglutinin and neuraminidase. Minor antigenic differences were demonstrated. A low-frequency mutant was recovered from erythrocytes when sequential eluates and erythrocytes were inoculated separately. Differences in thermostability, and in anatomical site and time of virus liberation from infected chickens were also used successfully to separate mutants.

Newcastle disease virus: evaluation of an avirulent enteric isolate as a viable vaccine

Abstract: SUMMARY An avirulent enteric isolate of Newcastle disease virus from Northern Ireland was evaluated as a viable vaccine. Viable virus was recovered for at least 3 days when it was diluted in water containing powdered skimmed milk and held at 37 C. Chicks were infected by administering the virus in drinking water. Eight experiments with parentally immune and unimmune chicks demonstrated antibody formation in nearly all birds following administration of the virus in drinking water. The chicks received the virus when they were as young as one day old. When their immunity was challenged with the virulent GB strain of NDV by contact exposure, a high percentage of birds previously exposed to the N. Ireland isolate survived. They were, however, infected by the challenge strain, resulting in signs of respiratory disease, virus shedding, and a boost in antibody titers. Several considerations for and against this type of vaccine are discussed.

Enhancement of bacterial infections in mice by Newcastle disease virus.

Abstract: This report describes an attempt to define the factors which incite secondary bacterial pneumonias. Groups of mice were given bacteria intraperitoneally and, at various intervals, Newcastle disease virus intravenously. There was an increase in the number of deaths and in the rates of death in these groups, when compared with a control group which was given only bacteria. These results were obtained with Streptococcus pneumoniae (Diplococcus pneumoniae), Pseudomonas aeruginosa, and Salmonella enteritidis ser. typhimurium. Newcastle disease virus increased the mortality rate of mice with bacterial infections when the two agents were given within 24 hr.

Proteins of four biologically distinct strains of Newcastle disease virus.

Abstract: SummaryVirions of NDV show strain specific variation in the proportions of proteins which they contain.

Mutation frequency of red and clear plaque types of the Hickman strain of Newcastle disease virus.

Abstract: SUMMARY Virus populations of the red plaque type of the Hickman strain of Newcastle disease virus were found to have a high rate of mutation from red to clear. Mutation of clear plaque virus from clear to red, if any, was so infrequent that it was not detected in the experimental trials. It is suggested that population components with a high rate of mutation are a common characteristic of Newcastle disease virus populations in nature. These components are often lost, either inadvertently or deliberately, from laboratory cultures. The loss may be advantageous for some virological studies but it makes other studies, particularly pathological and epizootiological studies, of questionable value.

Production of Hemadsorption-Negative Areas by Serums Containing Australia Antigen

Abstract: Exposure of human Wi-38 cells to human serums containing Australia antigen, and presumably serum hepatitis virus, renders the cells refractory to infection by Newcastle disease virus as detected by the hemadsorption-negative plaque test for intrinsic interference. Induction of the Newcastle disease virus refractory state could be passed in cell culture with up to a 1 : 100,000 dilution of material obtained from cells "infected" with serums containing Australia antigen after filtration (0.45-µm pores) and heating to 60°C for 1 hour. Human antiserums to the Australia antigen prevented induction of the Newcastle disease virus refractory state.

Immunofluorescence of avian infectious bronchitis virus and Newcastle disease virus in singly and dually infected cell cultures.

Abstract: On the basis of immunofluorescence microscopy, avian infectious bronchitis virus (IBV) and Newcastle disease virus (NDV) were specifically and differentially identified in single and dual infections of primary chicken embryo kidney cells (CEKC). In singly infected CEKC cultures, the size and number of foci of virus-infected cells was related directly to the virus concentration of the inoculum and the time of virus replication. Evidence of interference of NDV by IBV was observed in dual infections of CEKC. NDV replicated as well in baby hamster kidney cells (BHK-21) as in CEKC, but there was no evidence that IBV infected BHK-21 cells.

The effect of parental immunity on the response of five-days-old chicks to intranasal vaccination with F strain Newcastle disease virus

Abstract: Two flocks of chicks from parents not immune to Newcastle disease (ND) virus and six flocks from immune parents were vaccinated intranasally with 106.03 to 106.86 mean embryo infective doses of F strain ND virus on the fifth day of life. A group of chicks from each flock was left unvaccinated. Vaccinated and unvaccinated chicks from each flock were killed on days one to ten and then every other day until 39 to 61 days. Serums were examined by the ND virus haemagglutination-inhibition (HI) test, and tissues were inoculated into fertile hens' eggs for recovery of vaccine virus. Vaccine virus was recovered from vaccinated nonparentally-immune chicks daily from two to 14 days post-vaccination. Their serological response was detectable two days post-vaccination and reached peak levels nine to 14 days post-vaccination. In contrast, vaccine virus was recovered rarely or not at all from parentally-immune chicks and their serological response was much less than in chicks with no parental immunity. It is concluded that parentally-acquired antibodies neutralised vaccine virus so reducing the amount of immunizing virus antigen to which the host was exposed.

Vaccination response of parentally immune chicks after yolk-sac inoculation of the embryo with inactivated Newcastle Disease Virus.

Abstract: Eggs from hens immune to Newcastle disease virus (NDV) were inoculated into the yolk sac with formalin-inactivated F strain NDV on the ninth day of incubation. Chicks hatched from these eggs had lower levels of parentally acquired NDV antibodies than chicks from uninoculated eggs. Chicks from inoculated eggs showed a better serological response to intranasal vaccination at five days old with live F strain NDV than did chicks from uninoculated eggs.