The immune response of broiler chickens exposed to intra-tracheal (i.t.) administration of benzo[a]pyrene (BaP) with and without Nigella sativa (Ns) supplementation was investigated. A total of 120 day-old chicks were divided into four groups comprising 30 birds each, into a control, Ns, BaP, and BaP+Ns group. Immune responses to Newcastle disease (ND) were evaluated by haemagglutination inhibition (HI), phytohaemagglutinin (PHA) skin test and carbon clearance assay (CCA). In most instances, there was a significant increase (p<0.05) in the ND-HI antibody titers, PHA skin-swelling response and phagocytic activity in the BaP + Ns group compared to that of the BaP group. Likewise, organ weight and indices of the spleen, bursa of Fabricius and thymus of birds from the BaP + Ns group were also higher (p<0.05) than that of the BaP group from day 1 until day 21. It is concluded that exposure to BaP may exert adverse effects on the immune system of broilers which may increase their susceptibility to disease, and Ns supplementation significantly reduces these alterations.
A case of Newcastle disease virus infection in a female laboratory technician is reported for the first time in Malaysia. Infection was acquired by droplet infection of the eye while grinding infected chicken in the laboratory. The case was confirmed by isolation of Newcastle disease virus from an eye swab taken from the subject on the first day of clinical signs. A four-fold rise of haemagglutination-inhibition titre was shown when sera on the third day of infection and 15 days later were compared.
One-day-old chickens were transported from Australia to Malaysia and vaccinated orotracheally with an uninactivated vaccine prepared from avirulent Australian V4 strain of Newcastle disease virus (NDV). The vaccination regimes were as follows: group A, once, at 2 weeks old; group B, once, at 3 weeks old; group C, twice, at 2 and at 3 weeks old; group D, direct contact with groups A, B, and C; and group E, indirect contact with groups A, B, C, and D. Group F was unvaccinated controls. Challenge was with NDV virulent Ipoh AF 2240-226 strain, administered at 4 weeks old intramuscularly to 10 chickens in each group and orotracheally to 10 chickens in each group. The remaining chickens were challenged by contact with the inoculated chickens. Group mortalities following challenge were: A, 1/77; B, 1/34; C, 0/39; D, 0/45; E, 6/43; and F, 60/60.
A panel of six monoclonal antibodies (mAbs) against the nucleocapsid (NP) protein of Newcastle disease virus (NDV) was produced by immunization of Balb/c mice with purified recombinant NP protein. Western Blot analysis showed that all the mAbs recognized linearized NP epitopes. Three different NP antigenic sites were identified using deleted truncated NP mutants purified from Escherichia coli. One of the antigenic sites was located at the C-terminal end (residues 441 to 489) of the NP protein. Two other antigenic sites were located within the N-terminal end (residues 26-121 and 122-375). This study demonstrates that the N- and C-terminal ends of the NP proteins are responsible in eliciting immune response, thus it is most likely that these ends are exposed on the NP.
Plasmid DNA (pDNA)-based vaccines have emerged as effective subunit vaccines against viral and bacterial pathogens. In this study, a DNA vaccine, namely plasmid internal ribosome entry site-HN/F, was applied in ovo against Newcastle disease (ND). Vaccination was carried out using the DNA vaccine alone or as a mixture of the pDNA and dextran-spermine (D-SPM), a nanoparticle used for pDNA delivery. The results showed that in ovo vaccination with 40 μg pDNA/egg alone induced high levels of antibody titer (P<0.05) in specific pathogen-free (SPF) chickens at 3 and 4 weeks postvaccination compared to 2 weeks postvaccination. Hemagglutination inhibition (HI) titer was not significantly different between groups injected with 40 μg pDNA + 64 μg D-SPM and 40 μg pDNA at 4 weeks postvaccination (P>0.05). Higher antibody titer was observed in the group immunized with 40 μg pDNA/egg at 4 weeks postvaccination. The findings also showed that vaccination with 40 μg pDNA/egg alone was able to confer protection against Newcastle disease virus strain NDIBS002 in two out of seven SPF chickens. Although the chickens produced antibody titers 3 weeks after in ovo vaccination, it was not sufficient to provide complete protection to the chickens from lethal viral challenge. In addition, vaccination with pDNA/D-SPM complex did not induce high antibody titer when compared with naked pDNA. Therefore, it was concluded that DNA vaccination with plasmid internal ribosome entry site-HN/F can be suitable for in ovo application against ND, whereas D-SPM is not recommended for in ovo gene delivery.
Newcastle disease (ND) is a highly contagious avian disease and one of the major causes of economic losses in the poultry industry. The emergence of virulent NDV genotypes and repeated outbreaks of NDV in vaccinated chickens have raised the need for fundamental studies on the virus-host interactions. In this study, the profiles of B and T lymphocytes and macrophages and differential expression of 26 immune-related genes in the spleen of specific-pathogen-free (SPF) chickens, infected with either the velogenic genotype VII NDV strain IBS002 or the genotype VIII NDV strain AF2240, were evaluated. A significant reduction in T lymphocyte population and an increase in the infiltration of IgM+ B cells and KUL01+ macrophages were detected in the infected spleens at 1, 3 and 4 days post-infection (dpi) (P<0.05). The gene expression profiles showed an up-regulation of CCLi3, CXCLi1, CXCLi2 (IL-8), IFN-γ, IL-12α, IL-18, IL-1β, IL-6, iNOS, TLR7, MHCI, IL-17F and TNFSF13B (P<0.05). However, these two genotypes showed different cytokine expression patterns and viral load. IBS002 showed higher viral load than AF2240 in spleen at 3 and 4dpi and caused a more rapid up-regulation of CXCLi2, IFN-γ, IL-12α, IL-18, IL-1β, iNOS and IL-10 at 3dpi. Meanwhile, the expression levels of CCLI3, CXCLi1, IFN-γ, IL-12α, IL-1β and iNOS genes were significantly higher in AF2240 at 4dpi. In addition, the expression levels of IL-10 were significantly higher in the IBS002-infected chickens at 3 and 4dpi. Hence, infection with velogenic genotype VII and VIII NDV induced different viral load and production of cytokines and chemokines associated with inflammatory reactions.
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.