Comparison of two experimental binary ethylenimine (BEI) inactivated Newcastle disease oil-emulsion vaccines.

Mesogenic R2B Mukteswar strain of Newscastle disease virus derived from tissue culture and allantoic fluid was inactivated with binary ethylenimine (BEI). Oil-emulsion vaccines using both substrates were prepared and tested for their potency in chickens. The vaccines elicited a good serological response as assessed by haemagglutination inhibition (HI) test and had an adequate potency as evaluated by challenge test.     

Isolation of Newcastle disease virus from phasianidae birds in Hong Kong

Highly velogenic strains of Newcastle disease virus were isolated in Hong Kong from Chinese francolins (Francolinus pintadeanus) and bamboo chickens (Bambusicola thoracica) imported from the People's Republic of China.     

Newcastle disease virus evolution. II. Lack of gene recombination in generating virulent and avirulent strains

Sequence analysis and comparison of the fusion glycoprotein genes of 11 Newcastle disease virus (NDV) isolates indicated a high degree of functional and structural constraint exerted on the change of the glycoprotein. However, synonymous nucleotide substitutions occurred frequently throughout the coding region. Facilitated by an analysis of synonymous difference (Ks) in pairwise strain comparison, we defined the branching orders of the strains and identified three distinct evolutionary lineages correlating with the virulence as expressed by mean death time (MDT) for chick embryo. The typically virulent strains with MDT of about 50 hr were associated with one lineage, while the typically nonvirulent strains with MDT of infinity were of another lineage. The third lineage consisted of both virulent and avirulent strains whose MDTs lay on a continuum from 50 to 120 hr. Synonymous substitutions were found to occur with almost the same rates in the adjacent hemagglutinin-neuraminidase and membrane protein genes as in the fusion protein gene, and the branching orders based upon the Ks for these genes were essentially identical to those derived from the fusion protein gene. Therefore, no gene exchange by recombination seems to have occurred to generate the strains of distinct lineages. Rather, the different strains appear to have evolved through various degrees of accumulation of point mutations. Besides these evolutionary features, the present study strongly supports the importance of the previously identified signals for gene expression and for the proteolytic activation of the gene product.     

Interaction between a live avian pneumovirus vaccine and two different Newcastle disease virus vaccines in broiler chickens with maternal antibodies to Newcastle disease virus.

Broiler chicks with maternal antibodies to Newcastle disease virus (NDV) but none to avian metapneumovirus (APV) were divided into six groups. One group was kept as an unvaccinated control group. Three of the other groups were vaccinated at 1 day old with live APV vaccine or one of two live NDV vaccines (VG/GA or HB1). The remaining two groups received the APV vaccine in combination with either of the two NDV vaccines at 1 day old. At intervals after vaccination for up to 42 days, distribution of the viruses in the tissues was monitored, together with humoral antibody responses. Few NDV isolations were made from any NDV-vaccinated chicks, probably due to the presence of NDV maternal antibodies. In both dual-vaccinated groups, APV persisted longer (up to 21 days post vaccination (d.p.v.)) than in the single vaccinates (up to 14 d.p.v.). After 14 d.p.v., antibody titres against APV in both dual-vaccinated groups remained higher than the single APV vaccinates. For NDV haemagglutination inhibition antibodies, similar titres were found in the single and dual NDV VG/GA vaccinates. However, for chickens dually vaccinated with NDV HB1 and APV, the haemagglutination inhibition titres were significantly higher at 21 and 28 d.p.v. than the single HB1 vaccinates. These differences reflect the fact that NDV haemagglutination inhibition titres may depend on the NDV vaccine used.     

Specific interference among strains of Newcastle disease virus. I. Demonstration and measurement of the interference

A non-plaque-forming vaccine strain of NDV (NDV-B1) interferes with the infection of cultured chick embryo cells by the virulent plaque-forming NDV-L strain. The level of interference increases when the concentration of interfering virus is increased or when the time between infection and superinfection is increased. Only at multiplicities of superinfection of less than one does one obtain an accurate measure of the degree of interference. The direct assay technique for measuring the extent of interference is compared with the infective center assay, and the superiority of the latter in interference experiments is demonstrated. A procedure for plating infective centers is described which insures that the majority of plaques formed in the infective center assay are due to infected cells and not reversibly attached or free virus.     

Comparison of protein and lipopolysaccharide patterns of several Coxiella burnetii strains in phase I

Electrophoresis in polyacrylamide gel gradients in the presence of sodium dodecyl sulphate revealed at least 18 identical protein bands in eight strains of Coxiella burnetii. By staining with Coomassie Brilliant Blue R-250 it was possible to visualize clearly at least 40 proteins. The protein pattern showed the greatest variability in the region from 27 to 18.5 kD. Strains S and Priscilla differed from the other strains also in proteins smaller than 18.5 kD. The lipopolysaccharide pattern obtained by the same technique consisted of from 6 to 12 various bands in the region from 23.5 to 11.8 kD. The protein and lipopolysaccharide patterns of four strains isolated from ticks did not significantly differ from those of strains Henzerling and L-35 isolated from men.     

Characterization of genotype IX Newcastle disease virus strains isolated from wild birds in the northern Qinling Mountains,China

This study was conducted to evaluate the virulence and evolution of genotype IX Newcastle disease virus (NDV) isolates obtained from wild birds in the northern Qinling Mountains of China. Five isolates were obtained from 374 larynx and cloacae swabs, which were collected from multiple asymptomatic wild bird species from August 2008 to July 2011, and were subsequently characterized by pathotype and genotype. Deduced amino acid sequences revealed that all five NDV isolates exhibited velogenic fusion protein cleavage sites motif ¹¹²R-R-Q-R-R-F¹¹⁷, shared as high as 99.8–99.9 % homology with each other, and varied in pathotype by intracerebral pathogenicity indices (ICPI) of 0.425–1.638. Phylogenetic analysis showed that all five isolates were clustered to genotype IX NDV. This is the first study to confirm multiple asymptomatic wild bird species as natural carriers of virulent genotype IX NDV. A novel NDV isolate from the Spotted-necked Dove (family Columbidae) exhibited discordance between its lentogenic ICPI and its virulent proteolytic cleavage site motif ¹¹²R-R-Q-R-R-F¹¹⁷. Although the five isolates underwent several amino acid mutations in the fusion protein, evidence of continuous evolutionary divergence did exist in the genotype IX NDV, which was always regarded as a conservative genotype.     

Molecular-biological characterization of Marek's disease virus. II. Differentiation of various MDV and HVT strains

Immunological cross-reactions were found between each of the four major virus-specific polypeptides of Marek's disease virus (MDV) strains CVI 988, K and HPRS-16/att, and herpesvirus of turkey (HVT) Fc126 by one-dimensional (1D) gel analysis of immunoprecipitates from the lysate or culture medium of infected cells. The results, however, did not allow a serotype classification of MDV and HVT strains. Comparison of the two-dimensional (2D) gel patterns of virus-specific polypeptides of nine MDV and HVT strains with different biological properties revealed many similarities. Strain CVI 988 provided the reference pattern, consisting of 35 polypeptides, 18 of which were glycosylated. Based on their similarities in migration characteristics (size, charge, and heterogeneity of spots) during 2D gel electrophoresis, 11 virus-specific polypeptides or polypeptide complexes were identified in the patterns of nearly all virus strains analyzed. One of these polypeptides was glycoprotein gp5, the putative A antigen of MDV and HVT, which was also detected in the medium of cells infected with HPRS-16/att, a strain which was reported to have lost its capacity for production of A antigen. In addition to the similarities mentioned above, differences were found in migration behavior of virus-specific polypeptides (complexes) p4/p5/p6, gp3, gp5, and gp8/gp9, which were confirmed by coelectrophoresis experiments. The most conspicuous difference was found between three patterns of gp5 which seem to be characteristic for three groups of viruses: (I) high- and low-virulent MDV strains and their attenuated variants; (II) avirulent and apparently nononcogenic MDV strains; (III) herpesviruses of turkey. The minor differences found for the other polypeptides mentioned above further substantiated this molecular-biological classification of MDV and HVT strains and, in addition, enabled the differentiation of two HVT strains within molecular-biological group III.     

Biochemical changes in chicken serum during infection with strains of Newcastle disease virus of differing virulence. I. Enzyme study

Chickens aged 5-6 weeks were inoculated with 3 strains of Newcastle disease virus of differing pathogenicity. The levels of the enzymes lactate dehydrogenase (LDH), isocitrate dehydrogenase (ICDH), cholinesterase (ChE), alkaline and acid phosphatase (ALP and AcP), glutamate-oxaloacetate and glutamate-pyruvate transaminases (GOT and GPT) in serum were measured. Significant decreases in the levels of ChE and ALP were found in chickens infected with high doses of a velogenic strain of virus. The levels of LDH, ICDH and GOT were elevated in these chickens, but the levels of AcP and GPT were unchanged. ALP levels were slightly decreased and LDH levels were slightly elevated in chickens that were inoculated with a mesogenic strain. No significant changes in enzyme levels were found in chickens infected with lentogenic virus. Changes in enzyme levels were found to be correlated with the clinical findings in the infected chicks.     

Pathological and virological features of arenavirus disease in guinea pigs. Comparison of two Pichinde virus strains.

A guinea pig passage-adapted strain of the arena-virus Pichinde (adPIC) is highly virulent in inbred guinea pigs, whereas the related strain PIC3739 is attenuated. Both viruses were macrophage tropic and infected peritoneal, splenic, liver, and alveolar macrophages during experimental Pichinde virus infection. Infection with the virulent strain was associated with unlimited viral replication in the face of exaggerated delayed-type hypersensitivity response, manifested by the macrophage disappearance reaction. Histopathological lesions unique to adPIC-infected guinea pigs included intestinal villus blunting with mucosal infiltration by pyknotic debris-laden macrophages and apoptosis of crypt epithelial cells. Splenic red pulp necrosis was also significantly associated with adPIC infection but not PIC3739 infection. These findings may provide clues to the pathogenesis of a group of poorly understood human viral hemorrhagic fevers.     

The effect of mixed live vaccines of Newcastle disease and infectious bronchitis on the chicken respiratory tract.

The effect of mixed live vaccines of Newcastle disease (ND) and infectious bronchitis (IB) on specific pathogen-free chickens aged 7 days was investigated. The chickens were inoculated intranasally with mixed live vaccines with and without Escherichia coli, or with E. coli alone. "Vaccine 1" consisted of ND virus strain B1 and IB virus strain ON; "vaccine 2" consisted of ND virus strain B1 and IB virus strain H120. The tracheas of chickens inoculated with the vaccines and E. coli and with the vaccines alone showed multiplication of E. coli and histological lesions (loss of cilia, degeneration and hyperplasia in epithelial cells and cellular infiltration of subepithelial tissues). In the tracheas of chickens inoculated with vaccines and E. coli, multiplication of E. coli was greater than in chickens given vaccine alone. There were no histological lesions, and only mild, transient multiplication of E. coli in chickens inoculated with E. coli alone. The results suggest that these mixed live vaccines, especially vaccine 2, play a role in inducing or enhancing colibacillosis in the chicken.