Studies on the host-cell range of influenza and Newcastle disease viruses.
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Different vaccination programmes commonly used in Moroccan poultry farms were tested for their capacity to protect chickens against two representative Moroccan strains of velogenic viscerotropic Newcastle disease virus under controlled conditions. All vaccination programmes protected the chickens against mortality and the inactivated vaccine gave the highest antibody titres and the best protection against respiratory symptoms.
Seven Newcastle disease (ND) virus (NDV) isolates which were recovered from ND outbreaks in chicken and pigeon flocks in China and Taiwan between 1996 and 2000 were genotypically and pathotypically characterized. By phylogenetic analysis of the fusion protein genes, isolates Ch-A7/96, Ch/98-3, Ch/99, Ch/2000, and TW/2000 were placed into two novel subgenotypes, VIIc and VIId. Isolate Ch/98-1 was grouped into subgenotype VIb, while Ch-W6/96 was proven to be a mixture of isolates Ch-A7/96 and Ch/98-1. These isolates were pathotyped as viscerotropic velogenic for Ch/98-3, Ch/99, Ch/2000, and TW/2000; neurotropic velogenic for Ch-A7/96; and mesogenic for Ch/98-1. Three separate, comparative, genetic analyses of the F genes, including genetic distance measurement, phylogenetic tree analysis, and residue substitution analysis, were performed with our isolates and selected NDV strains from GenBank. Results showed that the close genetic similarity provided evidence for the epidemiological linkage between the outbreaks in China and Taiwan and that the 1990s outbreaks in Asia, the Middle East, Africa, and Europe constituted the fourth panzootic of ND. In combination with epidemiological analysis, an evolutionary model of the NDV strains, representative of the direction of transmission within the NDV strains, was proposed, and epidemiology of NDV transmission was evaluated with emphasis on molecular aspects. Finally, a cross-protective experiment indicated that at least one strain (Ch-A7/96) among our NDV isolates was an antigenic variant, responsible for recent outbreaks of ND in vaccinated chicken flocks.
A series of monoclonal antibodies (MAbs) against the haemagglutinin-neuraminidase (HN) and fusion (F) glycoproteins and the matrix (M) protein of Newcastle disease virus (NDV) were tested for protective effects in passive immunization of newborn chickens against challenge with a virulent heterologous strain of NDV (Italien). MAbs with high virus-neutralizing activity directed to one antigenic site of the HN protein delayed virus growth and significantly prolonged survival time, but all chickens eventually succumbed to infection. MAbs directed to two antigenic sites of the F protein completely suppressed virus growth and prevented death of chickens, although the neutralizing activities of these anti-F MAbs were lower than those of the above anti-HN MAbs. Combined administration of the anti-HN and anti-F MAbs had a synergistic protective effect, but no protective effects were shown by MAbs against the M protein.
Virions prepared from a non-revertible temperature-sensitive (ts) mutant (ts53) of Newcastle disease virus (NDV) grown in ovo at the permissive temperature (34 degrees C) possessed thermolabile haemagglutination and neuraminidase activities compared with parental (ts+) virions. Purified haemagglutinin-neuraminidase (HN) protein from ts53 virions was also more thermolabile than ts+ HN protein. SDS-PAGE analysis of [3H]leucine pulse- and pulse/chase-labelled NDV proteins synthesized in chick embryo fibroblasts following infection with ts+ and ts53 virus revealed that ts53 matrix (M) protein was unstable and disappeared during chase incubations only at the non-permissive temperature (42 degrees C). The non-revertibility of the ts53 mutant may indicate that it is a double mutant affected in both HN and M genes; alternatively this mutant may only be affected in the HN gene, the close physical association of the thermolabile HN with the M protein during virus maturation resulting in the lack of protection of the M protein from the action of cellular proteases at the non-permissive temperature.
A comparison of haemagglutination inhibition (HI) and enzyme-linked immunosorbent assay (ELISA) techniques for the detection of antibodies against Newcastle disease virus in sera from persons working in poultry farms and veterinary vaccine institutes and from the general population revealed that 22% more sera were positive by ELISA compared to HI. No samples were negative by ELISA but positive by HI. While HI titres of positive sera were found in the range 8-64, ELISA titres were between 16 and 512. It was interesting that though 78% sera had concordant results by the two tests, titres obtained by ELISA were nearly six times higher than those by HI.
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Explore the source record for details and available documents.
Explore the source record for details and available documents.
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A fowl pox-based recombinant virus TROVAC-NDV (vFP96.5) was developed expressing the fusion and hemagglutinin-neuraminidase glycoproteins from a velogenic strain of Newcastle disease virus (NDV). Studies in specific-pathogen-free birds indicated that inoculation of a single dose of the recombinant led to the induction of significant levels of hemagglutination-inhibiting antibody that were maintained to 8 wk postinoculation. Further, the recombinant induced protective immunity against a combined intramuscular velogenic NDV challenge and respiratory NDV challenge. In commercial broiler chickens that were inoculated in the presence of maternally derived NDV immunity, the level of the NDV-specific humoral response was dampened, but significant levels of protection against both a lethal intramuscular NDV challenge and a fowl poxvirus challenge were obtained.
Chickens aged five to six weeks were inoculated with three strains of Newcastle disease virus of differing pathogenicity. The serum level of the metabolites: total protein, albumin, globulin, uric acid, total lipids, cholesterol and electrolytes: calcium, magnesium, sodium and potassium were determined. The changes in serum levels of metabolites were as follows: velogenic infection was accompanied by decrease in total protein and albumin, reduction of lipids and cholesterol and increase in uric acid. No significant changes were found in the values of these metabolites in the serum of chickens infected with mesogenic strain. Lentogenic strain caused elevation of uric acid and cholesterol. All three strains caused decrease of the level of potassium in serum.
We have determined the sequences of the 5' ends of three strains of Newcastle disease virus, permitting the assembly of the entire genomic sequence, which amounts to 15,186 nucleotides. This length is in agreement with the rule of six, which has been shown to determine replication efficiency in similar viruses. Comparison of the extreme 5' end of the trailer sequence with that of the 3'-terminal leader sequence of the virus reveals a high degree of complementarity. Variation between the 5'-terminal sequences of the different strains reveals the presence of alternative L gene polyadenylation signals, leading to correspondingly different trailer lengths.
An immunoaffinity method was designed for purification of a soluble form of the matrix (M) protein of Newcastle disease virus. The resulting M protein sedimented in a sucrose gradient as a small complex. This purified M protein associated with liposomes containing a net neutral, negative, or positive charge. The liposomes were composed of phosphatidylcholine, cholesterol, and a third lipid which provided the charge. The M protein-liposome associations were not prevented by high salt conditions. These observations are consistent with a nonelectrostatic association between the M protein and liposomes. Monoclonal antibodies to three separate epitopes of the M protein were all able to bind M protein complexed with liposomes, suggesting that the three M protein epitopes are not directly involved in the interaction between the M protein and liposomes. The M protein was also able to associate with liposomes lacking cholesterol implying that cholesterol does not play a substantial role in the M protein-liposome interaction.
The fusion (F) glycoprotein of Newcastle disease virus (NDV) contains a predicted amphipathic alpha-helix C-terminal to its fusion domain. Of the 13 available NDV F protein sequences, only the Australia-Victoria (AV) strain alpha-helix is weakened, by the replacement of Ala159 with Thr. In this report, we demonstrate that the efficiency of cleavage and virion incorporation of the AV F protein, unlike that of other strains, is temperature sensitive. Pulse/chase experiments at 42 degrees revealed disulfide-linked aggregates containing both the F and hemagglutinin-neuraminidase glycoproteins in strain AV, but not in strain Beaudette C. Furthermore, a revertant derived from AV, whose helix-weakening Thr159 has been replaced with the consensus Ala, produced fewer F protein aggregates, confirming the structural importance of this region in maturation. In addition, a novel disulfide-defined folding intermediate of the F protein was detected.
Sequence determinations of the hemagglutinin-neuraminidase (HN) glycoproteins of a temperature-sensitive mutant of Newcastle disease virus and two sequentially selected revertants had previously shown that substitution at a pair of residues, 129 and 175, resulted in a deficiency in neuraminidase (NA) activity, which was partially restored by a third substitution at residue 193. To evaluate the role of the substitution at residue 175 in diminished NA activity, the mutation was introduced into HN and the protein expressed in COS cells. The mutated HN not only had minimal NA activity but also was unable to absorb chicken erythrocytes, even though it was transported to the cell surface in normal amounts, in an apparently antigenic form. Attachment function was restored to the protein by the introduction of the additional substitution(s) at 129 and/or 193. These results indicate that residue 175 influences not only NA activity but also receptor recognition.