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A naturally acquired subclinical infection of infectious bursal agent was shown to be the probable causative factor of marked immunosuppression of Newcastle disease vaccine in young chicks. Old hens maintained in the same contaminated environment did not exhibit immunosuppression.
Two pathology-based techniques, immunohistochemistry and riboprobe in-situ hybridization, were applied to formalin-fixed, paraffin wax-embedded tissues from chickens infected with three different isolates of velogenic viscerotropic Newcastle disease virus (VVNDV). With the immunohistochemical method, viral protein was consistently detectable in the spleen and caecum at the terminal phase of the infection. With in-situ hybridization, viral nucleic acid was consistently detected in the eyelid, spleen and caecum in both the acute and terminal phases. Hybridization with anti-sense probe to detect viral mRNA was often more intense than hybridization with sense probe to detect viral genomic RNA.
In examination of colonial birds in the Volga delta in the Astrakhan region (188 bioassays from 229 birds) and in the Komandorskie Islands of the Kamchatka region (244 bioassays from 208 birds) in 1974, 15 strains of Newcastle disease virus (NDV) were isolated (8 strains from 7 birds and 7 strains from 12 birds, respectively). The strains were isolated from Egretta alba and Ardea cinerea, and Phalacracorax carbo in the Astrakhan region and from Lunda cirrhata and Uria aalge in the Komandorskie Islands. The isolates were obtained from tracheal and cloacal washings and from pools of viscera. These data are the first evidence of the existence of Newcastle disease virus foci in the USSR.
An indirect immunoperoxidase monolayer assay was used to measure the location of virus and class-specific antibodies to Newcastle disease virus (NDV) of chickens. The intra-ocular vaccination of chicks with the Ulster and Hitchner B1 strains of NDV resulted in the highest titre of virus being recovered from the Harderian gland (HG) at 10(6) iu/0.1 g tissue without any accompanying virus in the faeces. Maternal IgG antibody which was detected in the lacrimal fluid at 1/50 of serum levels of IgG antibody could prevent this replication. Lacrimal IgA antibody to NDV was shown to be absolutely dependent on local virus replication for its production because it reached titres of 10(3) after local intra-ocular infection compared with < 10(1.5) after two intravenous inoculations of inactivated virus. Biliary IgA, by contrast, reached 10(3.5) after either immunisation schedule. Lacrimal IgG and IgM antibody to NDV occurred at 1-9% of the titres of serum antibody to NDV after immunisation with inactivated virus or the passive transfer of NDV-immune serum between chickens. This percentage increased to 13-33% of serum titres after intra-ocular infection with NDV as if the local replication of NDV in the HG stimulated lacrimal antibody of all classes. This is the first report of NDV replication in the HG and of virus-specific IgM in the lacrimal fluid.
The use of Nobuto 's method for blood sampling with birds and mammals, using filter paper, suggests various advantages in the practice of serologic investigations. Studies were carried out to determine the immune titer of birds against Newcastle disease. Parallel blood samples were taken routinely and after the method of Nobuto with filter paper. Serologic examination was performed through the hemagglutination-inhibition test, beta procedure, with 10 HAU /0.5 cm3. As many as five parallel experiments with blood samples from birds were conducted within the period of from the 15th to the 40th day following vaccination. The results of HI-tests on filter paper, variants a and b, proved mathematically reliable, coinciding with the HI results with the samples studied with sera (P = 0.05). Further studies of blood samples from birds after the HI, beta micromethod, are currently carried out.
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Sublines homozygous for each of four MHC haplotypes were developed from randombred control populations of turkeys and challenged with Pasteurella multocida (capsular serogroup a, somatic serotype 3, 4) at 6 wk of age or Newcastle disease virus (NDV; Texas GB strain) at 4 wk of age. In addition, individuals from a randombred control line (RBC2) and a subline (F) of RBC2 long-term selected for increased 16-wk BW were included in most of the challenge trials. The duration of the challenge trials was 2 wk for both organisms. Mortality following challenge with P. multocida or NDV was higher in the F line than in its randombred control. The MHC genotypes differed in mortality following exposure to both organisms but the rankings of the genotypes were not the same for P. multocida and NDV. The increased susceptibility of the F line to both organisms could not be explained by known changes in the frequency of the MHC haplotypes.
Specific-pathogen free (SPF) chickens were inoculated with the plasmid constructs encoding the fusion (F) and haemagglutinin-neuraminidase (HN) glycoproteins of Newcastle disease virus (NDV), either individually or in combination and challenged with velogenic NDV. The antibody level against NDV was measured using commercial enzyme linked immunosorbent assay (ELISA). In the first immunization regimen, SPF chickens inoculated twice with NDV-F or NDV-HN constructs elicited antibody responses 1 week after the second injection. However, the levels of the antibody were low and did not confer significant protection from the lethal challenge. In addition, administration of the plasmid constructs with Freund's adjuvant did not improve the level of protection. In the second immunization regimen, chickens inoculated twice with the plasmid constructs emulsified with Freund's adjuvant induced significant antibody titers after the third injection. Three out of nine (33.3%) chickens vaccinated with pEGFP-HN, five of ten (50.0%) chickens vaccinated with pEGFP-F and nine of ten (90.0%) chickens vaccinated with combined pEGFP-F and pEGFP-HN were protected from the challenge. No significant differences in the levels of protection were observed when the chickens were vaccinated with linearized pEGFP-F. The results suggested that more than two injections with both F and HN encoding plasmid DNA were required to induce higher level of antibodies for protection against velogenic NDV in chickens.
The hybrid baculovirus constructed from Autographa california nuclear polyhedrosis virus (NPV) and Bombyx mori (silkworm) NPV was used for expression of fusion glycoprotein (F) of Newcastle disease virus (NDV) strain D26. The gene encoding F protein was introduced into the improved baculovirus expression vector derived from the host-range-expanded baculovirus. In Spodoptera frugiperda (fall armyworm) cells infected with a recombinant baculovirus, HyF121, the expressed F protein was properly located onto the cell surface. After silkworm pupae were infected with HyF121, a subunit vaccine against NDV was prepared from the HyF121-infected pupae. Chickens inoculated with the subunit vaccine were protected against virulent NDV challenge.
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A mucoprotein, present in normal human urine, has been isolated and obtained in a state of a high degree of purity. A number of the biological, chemical, and physicochemical properties of the substance have been studied. From the results obtained in the present investigation and those reported in succeeding papers (34, 35) it appears that the mucoprotein has a high molecular weight, i.e., of the order of 7.0 x 10(6), consists of thread-like molecules which have axial ratios of approximately 100, and is specifically antigenic. This substance, which appears to be free of contaminating material, possesses in extraordinary degree the capacity to react with influenza, mumps, and Newcastle disease viruses. At equilibrium, with influenza virus, the minimal amount of the substance capable of giving a demonstrable reaction with one hemagglutinating unit of virus appears to be about 0.0003 microg. The mucoprotein is altered by preparations of influenza viruses and its capacity to react with these agents or others is lost. The kinetics of the inactivation process brought about by influenza viruses is in accord with those of well known enzyme-substrate systems. With the exception of the capacity to react with viruses, altered mucoprotein did not differ from the native substance relative to any of the properties examined in the present study. That certain physicochemical properties of the altered mucoprotein are different from those of the native substance is demonstrated in succeeding papers (34, 35).
Layer chickens on a commercial started pullet farm were vaccinated once at 31 to 52 days of age by drinking water or aerosol with live V4 Newcastle disease virus (NDV) vaccine. Flockmates which had been rehoused in laboratory isolation pens shortly beforehand were similarly vaccinated. Samples of birds were bled at intervals and the serums tested for haemagglutination inhibiting antibody to NDV. Log2 mean titres of up to 4.88 and assumed protection levels (based on the percentage of birds with log2 titres of 4 or greater) of up to 81%, were obtained in the field trials within 4 weeks of vaccination. A subsequent laboratory trial further compared the response of different breeds of chicken to different routes of vaccination. Differences were observed between breeds, routes of vaccination, and parallel field and laboratory trials. The results show that this V4 vaccine can produce an adequate serological response following mass vaccination of Australian layer pullets housed under commercial conditions, and that care should be exercised in extrapolating results obtained under laboratory conditions.
Homologous and heterologous viral interference is a common occurrence that has been well studied in vitro. In the present study, homologous viral interference between the LaSota and NYP strains of Newcastle disease virus (NDV) was studied in vivo in chickens, the natural host for NDV. The LaSota strain is avirulent and widely used as a vaccine in poultry industry, while the NYP strain is highly virulent and causes acute disease and death in chickens within four to six days after infection. Chickens generally became resistant to NYP strain challenge 12 hours after intranasal or intratracheal inoculation with LaSota strain virus. The resistance was manifested by reduction in chicken morbidity and mortality, decrease in virus replication in the chicken respiratory tract (p less than 0.05), and inhibition of NYP strain induced gross and microscopic lesions. Interferon was first detected in the chicken respiratory tract and blood at 3 to 6 hours; it peaked at 12 to 24 hours and was maintained for 48 hours after viral inoculation, indicating that interferon induction might be one possible mechanism of the interference between the two strains. This study suggests a role for viral interference in vaccination against virulent viruses.
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Thirteen viruses isolated from feral birds and one isolated from a domestic duck, obtained in 1979-1980 during a survey of birds in Western Australia, were shown to be Newcastle disease viruses of low virulence for chickens. The binding of mouse monoclonal antibodies, raised against NDV-Ulster 2C to MDBK cells infected with the isolates was assessed using an indirect immunoperoxidase test. Five viruses caused binding of all 9 monoclonal antibodies tested, whereas the other 9 isolates induced binding of only 4 monoclonal antibodies.