Newcastle Disease Vaccine In Chickens Research Articles

Immune Responses in the Harderian Gland After Newcastle Disease Vaccination in Chickens with Maternal Antibodies.

Immune responses in the Harderian gland (HG) were characterized after Newcastle disease virus (NDV) LaSota ocular vaccination in antibody-naïve specific-pathogen-free (SPF) chickens and in chickens of commercial origin with NDV maternally derived antibodies (MDA). Ocular LaSota vaccination of 13-day-old white leghorn SPF chickens elicited serum antibody levels that consistently increased 15 days postvaccination, while the specific IgA response in lacrimal fluids was already detectable 10 days after vaccination. Eleven days postvaccination, the relative abundance of B cells, as well as T-helper cells (CD4+) and cytotoxic T cells (CD8+), in HGs was significantly increased, achieving maximum frequencies 16 days postvaccination. In a second experiment, chickens with MDA originating from NDV-vaccinated commercial white leghorn layer breeders, as well as white leghorn SPF chickens, were vaccinated with NDV LaSota. The LaSota virus successfully replicated in periocular tissues and in the trachea both in commercial and control SPF chickens after vaccination at 2 or 15 days of age (DOA). Vaccination at 2 DOA did not induce a serum NDV antibody response in chickens of commercial origin. In contrast, seroconversion was elicited in commercial chickens upon vaccination at 15 DOA, likely associated with waning of MDA. Unlike systemic IgG responses, vaccination at 2 or 15 DOA elicited strong specific IgA responses in lacrimal fluids in commercial chickens. The IgA response was highest 9 days after vaccination and showed a tendency to decline 15 days postvaccination. Commercial chickens vaccinated at 2 DOA showed increased B cells in HG 10 and 16 days postvaccination. The expansion of B cells in the HG in these chickens is consistent with increased IgA levels detected in lacrimal fluids. In contrast, control SPF chickens showed a more limited B-cell expansion in HG and lower IgA levels. Vaccination at 15 DOA also triggered a greater increase of B cells in HGs in commercial chickens than in control SPF chickens. The B-cell response was accompanied by T-helper (CD4+) cell expansion, occurring both in commercial and control SPF chickens. These cells expanded to a lesser extent when vaccination was performed at 2 DOA compared with vaccination at 15 DOA. CD8+ showed significant expansion irrespective of vaccination day and without differences detected between control SPF chickens and chickens with MDA. We conclude that NDV LaSota elicits vigorous humoral and cell immune responses in the HG. Furthermore, unlike the interference shown by MDA on vaccine-induced serum antibody responses, MDA do not interfere with the mucosal immune response of the HG.

Evaluation of immunostimulatory effects of a commercial herbal extract on avian influenza subtype H9N2 and Newcastle disease vaccination in chickens

Contrary to several vaccination programs to protect against bird flu and Newcastle disease (ND), these diseases remain a significant threat to the poultry industry. Improving the immune responses is important for many reasons such as vaccine failure, immunosuppressive diseases, and antibiotics misuse. Nowadays, research on materials likely to have immune-enhancing effects is increasing. Factors, substances, or compounds that can regulate different functions of the immune system can be used to enhance specific and even nonspecific responses to vaccines. The ability of herbal extracts to improve the immune system supports their use as immune stimulants. The present study aimed to examine the effects of barley malt extract in drinking water on humoral immunity of broiler chickens against ND and Avian Influenza (AI) disease subtype H9N2 vaccines. A total of 225 one-day-old broiler chicks (Ross strain) were divided into 5 groups of 3 subgroups and each subgroup had 15 chicks. Group A, B, and C chickens received 0.2%, 0.3%, and 0.5% of malt extract respectively in drinking water. Group D chickens did not get malt extract. Group E chickens did not receive malt extract and Newcastle and AI vaccines as the control group. All groups except group E were vaccinated with live Newcastle vaccine (B1 strain) intraocularly and AI-ND subtype H9N2 killed vaccine subcutaneously on the 7th day. Antibody titer against NDs and AI vaccines was considered by the Hemagglutination Inhibition test (HI test). Malt extract at 0.5% concentration, at all periods after vaccination, enhanced the systemic antibody response to ND vaccine in broiler chickens, but this extract had no significant effect on antibody response against the AI vaccine.Conclusion: Inoculation of ND vaccines with barley malt extract as an immune-boosting agent induces extensive immune responses involved in HI-NDV Ab titers.

Immune enhancing effects of Lactobacillus acidophilus on Newcastle disease vaccination in chickens

Introduction and purposeDespite the various vaccination programs for protection against New Castle disease, it remains an important threat to the poultry industry. The ability of the probiotic bacteria to improve the immune system in both animals and humans supports their use as immune adjuvants for vaccination. The aim of the present study was to examine the effects of Lactobacillus acidophilus in ND vaccination. Materials and methodsA total of 170 one day old chicks were divided in 5 groups. In groups A, B and C chicks were received L. acidophilus (5 × 109, 3 × 109 and 2 × 109) and also vaccinated with inactivated and attenuated ND vaccines. In group D, chicks only vaccinated without bacterial inoculation and group E was negative control with neither vaccine nor bacteria. Then IgG and HI NDV antibody titers were measured in all tested groups. ResultsIgG and HI NDV antibody levels were significantly higher in Lactobacillus treated groups especially in group A with 5 × 109 bacteria, than only vaccinated and negative control groups. Also antibody levels against NDV increased during the vaccination period especially in probiotic treated groups. ConclusionIn conclusion, L. acidophilus can use for improving immunogenicity of NDV vaccination programs.

Sunflower seed oil combined with ginseng stem-leaf saponins as an adjuvant to enhance the immune response elicited by Newcastle disease vaccine in chickens

The present study was to evaluate the adjuvant effect of sunflower seed oil containing saponins extracted from the stem and leaf of Panax ginseng C.A. Meyer (E515-D) on the immune response induced by an inactivated Newcastle disease virus (NDV) in chickens. The results showed that E515-D promoted significantly higher serum NDV-specific HI and neutralizing antibody responses, IFN-γ and IL-4 levels, and lymphocyte proliferative responses to Con A, LPS, and NDV antigen than the conventional adjuvant Marcol 52. Different adjuvant effect between E515-D and Marcol 52 may be attributed to different genes expressed in two groups. Transcriptome analysis of splenocytes showed that there were 1198 differentially expressed genes (DEGs) with 539 up and 659 down regulated in E515-D group while 1395 DEGs with 697 up and 698 down regulated in Marcol 52 group in comparison with the control group. Analysis of gene ontology (GO) term and kyoto encyclopedia of Genes and Genomes (KEGG) pathways showed that the predominant immune related pathways included “Toll-like receptor signaling pathway”, “NOD-like receptor signaling pathway”, “C-type lectin receptor signaling pathway”, and “Phosphatidylinositol signaling system” in E515-D group while Marcol 52 were “NOD-like receptor signaling pathway”, “Phagosome”, and “Lysosome”, and the most relevant DEGs in E515-D group were STAT1, STAT2, PI3K, and IL-6. Considering the excellent adjuvant activity and vegetable origin, E515-D deserves further study as an adjuvant for vaccines used in food animals.

Comparison of the Impact of Different Administration Routes on the Efficacy of a Thermoresistant Newcastle Disease Vaccine in Chickens

Route of vaccine administration has a great impact on immunization and protection outcomes in chickens. This study was conducted to compare the effect of different administration routes on the efficacy of a thermoresistant Newcastle disease (ND) vaccine (ND.TR.IR) in chickens. A total of 100 one-day-old specific pathogen-free chicks were divided into five groups (n = 20 chicks per group) and vaccinated through different routes at 10 and 20 days of age. Treatments included no vaccination (control [C]), 1 dose inoculation through eye drop (ED), 1 dose inoculation through drinking water (DW), 1 dose inoculation through feed (FV1), and 10 doses inoculation through feed (FV10). At 20 and 34 days of age, antibody titers were measured against ND virus (NDV) in all the chickens by hemagglutination inhibition (HI) test. Chicks immunized with ND.TR.IR vaccine through different routes of administration also were intramuscularly challenged with a local virulent NDV (vNDV) (Ck/ir/Beh/2011) 14 days after booster vaccination (at 34 days of age). Our results showed that in comparison with the FVs groups, the immunized chicks through ED induced a higher HI antibody titers at 20 days of age (p < 0.05). Meanwhile, vaccination through ED induced higher HI antibody titers at day 34 of age compared with all other groups (p > 0.05). The percentages of the protective HI antibody titers (≥log23) detected in ED and DW groups at 20 days of age were higher than those detected in the FV1 group (p < 0.05). However, routes of vaccination had no significant effect on the rate of protective titers at day 34 of age (100%, 90%, 75%, and 85% for ED, DW, FV1, and FV10, respectively). The percentage of post-NDV challenge survived chickens was not affected by the route of vaccination (p > 0.05), but immunization of chicks with ND.TR.IR in FV1 group provided relatively poorer protection when compared with the other groups (90% vs. 100%, respectively). Altogether, immunization of chicks with ND.TR.IR vaccine through different routes of administration induced protective NDV antibody HI titers, and provided protection against vNDV. However, when the vaccine was administrated through feed, a higher dose of vaccine is recommended.

The enhanced immunological activity of Paulownia tomentosa flower polysaccharide on Newcastle disease vaccine in chicken.

The extracts of Paulownia tomentosa (P. tomentosa) exhibit multiple pharmacological activities. In the present study, P. tomentosa flower polysaccharides (PTFP) were extracted by water decoction and ethanol precipitation, and the immunologic modulations of PTFP against Newcastle disease (ND) vaccine was investigated in chickens. The results showed that in a certain range of concentrations, PTFP treatment can dose-dependently enhance lymphocyte proliferation. Then, 280 14-days-old chickens were randomly divided into seven groups, and vaccinated with ND vaccine except blank control (BC) group. At the first vaccination, chickens were orally administrated with PTFP at concentration ranging from 0 to 50 mg/kg once a day for 3 successive days, and the BC group was treated with physiological saline. The lymphocyte proliferation rate, serum antibody titer, and levels of interferon-γ (IFN-γ) were respectively measured on 7, 14, 21, and 28 days after the first vaccination. The results showed that PTFP at the suitable doses could significantly promote lymphocyte proliferation, enhance serum antibody titer, and improve serum IFN-γ concentrations. Taken together, these data indicated that PTFP could improve the immune efficacy against ND vaccine in chickens, and could be as the candidate of a new-type immune adjuvant.

Effects of pidotimod soluble powder and immune enhancement of Newcastle disease vaccine in chickens

The aims of this study were to prepare pidotimod (PDM) soluble powder and to investigate the immune enhancement properties of PDM in chickens vaccinated with Newcastle disease virus vaccine. In vivo experiment, 360 6-day-old chickens were averagely divided into 6 groups. The chickens, except blank control (BC) group, were vaccinated with Newcastle disease vaccine (NDV). At the same time of the vaccination, the chickens in three PDM groups were given water with PDM for 5days, respectively, with the PDM at low, medium and high concentrations (0.25g/L, 0.5g/L, 1g/L), in control drug group was treated with 0.2ml/PDM dose via drinking water, in vaccination control (VC) and BC group, with equal volume physiological saline, once a day for five successive days. On days 14, 21 and 28 after the vaccination, the growth performance, the lymphocyte proliferation, serum antibody titer, the CD4/CD8 cell ratios and interleukin-2 (IL-2) and interferon-gamma (IFN-γ) were measured. The results showed that PDM at suitable dose could significantly promote growth performance, lymphocyte proliferation, enhance serum antibody titer, CD4/CD8 cell ratios and improve serum IL-2 and IFN-γ concentrations. It indicated that PDM could significantly improve the immune efficacy of Newcastle disease vaccine using doses of 0.5g/L, these results are consistent with the drug acting as an immunopotentiator.

Effects of polysaccharide from Ophiopogon japonicus on immune response to Newcastle disease vaccine in chicken

In order to investigate the immune enhancement effects of Ophiopogon japonicus polysaccharide Ophiopogon japonicus (OJPS) on Newcastle disease (ND) live vaccine, chickens vaccinated against ND live vaccine was orally administered with the OJPS at high, medium and low concentrations respectively. In negative control group, chickens were given orally equal volume of physiological saline. On day 14, 21 and 28, the serum antibody titer, erythrocyte-C3b receptor rosette rate (E-C3bRR), erythrocyte-C3b immune complex rosette rate (E-ICRR) and peripheral lymphocyte proliferation were measured. The results showed that at most time points, the antibody titer, peripheral lymphocyte proliferation, E-C3bRR and elimination rate of immune complex of three OJPS administrating groups were significantly higher (P<0.05) than those in negative control group. It indicated that OJPS could significantly improve the immune efficacy of Newcastle disease live vaccine, Ophiopogon japonicus polysaccharide possessed synergistical immunoenhancement.

Potentiating effect of pidotimod on immune responses of chickens to live attenuated Newcastle disease vaccines

Pidotimod is a synthetic dipeptide with immunomodulatory activity, but the capacity of pidotimod as an immunologic adjuvant to improve vaccine immunogenicity remains unclear. This study evaluated the effectiveness of pidotimod on immune responses of chickens to Newcastle disease (ND) vaccine, and its efficiency to improve protection against highly virulent ND virus (NDV). A total of 300 one-day-old broilers were divided into five groups (numbered I to V). Group I were unvaccinated and served as blank control group. Chickens in Group II to V were immunised with ND vaccine and supplemented with 0, 0.5, 1, 2 g/L of pidotimod in drinking water. The results showed that treatment with pidotimod (1 g/L) remarkably improved (p < .05) the potency of ND vaccine in chickens, as demonstrated by increased immune organ index (organ weight/body weight) and elevated antibody production. Meanwhile, no adverse effect on growth performance was observed. Moreover, as an adjuvant to ND vaccine, pidotimod (1 g/L) also dramatically promoted (p < .05) cell-mediated immunity, as characterised by increased lymphocytes proliferation and elevated ratio of CD4+ to CD8+ cells following NDV stimulation. Furthermore, administration of pidotimod (1 g/L) was efficient in inducing effective protection against lethal NDV challenge. Collectively, these data indicate that pidotimod may have the potential to be used as an effective vaccine adjuvant and the immunopotentiating effects deserve further study.

The immune adjuvant response of polysaccharides from Atractylodis macrocephalae Koidz in chickens vaccinated against Newcastle disease (ND)

Build on our previous research, polysaccharides from the rhizome of Atractylodis macrocephalae Koidz (RAMPS), RAMPStp and RAMPS60c were prepared and the structural characterization and immune response of ND vaccine in chicken were investigated. Immune organ index, Lymphocyte proliferation, antibody titers, cell cycle distribution, and percentages of CD4+ and CD8+ cells were determined. GPC analysis showed that the Mn of RAMPS with two peaks were 1.29×105 and 1.74×103, respectively. GC–MS analysis revealed that RAMPS was composed of glucose, mannose, arabinose, galactose, xylose, d-Ribose and rhamnose, with mass percentages of 66.39%, 21.24%, 5.64%, 2.65%, 2.30%, 1.15% and 0.64%, respectively. NMR spectroscopic analysis demonstrated that a preliminary structure of RAMPS was proposed as 1,3-linked β-d-Galp and 1,6-linked β-d-Galpresidues. In vivo test showed that RAMPStp and RAMPS60c could promote peripheral lymphocytes proliferation and entering into S and G2/M phases, enhance serum HI antibody titer and effectively improve the percentages of CD4+ and CD8+ T cells in chickens vaccinated with ND vaccine at most time points. The actions of RAMPStp and RAMPS60c were stronger than that of Lev, and RAMPStp presented the best efficacy. These results indicated that RAMPStp and RAMPS60c characterize of the immune-enhancing activity and RAMPStp possessed the strongest activity. It would be anticipated as a component of new-type immunopotentiator.

Assessment of Antibody Response to Newcastle Disease Vaccination in Chickens in Some Commercial Farms in Three Local Government Areas in Lagos State, Nigeria

Assessment of Antibody Response to Newcastle Disease Vaccination in Chickens in Some Commercial Farms in Three Local Government Areas in Lagos State, Nigeria

Sulfated glucan can improve the immune efficacy of Newcastle disease vaccine in chicken

To evaluate the immune effect of sulfated glucan from saccharomyces cerevisiae (SGSC) on chickens, two experiments were researched. In vitro experiment, the effects of SGSC on chicken splenic lymphocyte proliferation were determined. The results displayed that SGSC could significantly stimulate chicken splenic lymphocyte proliferation. In vivo experiment, 200 14-day-old chickens were averagely divided into 5 groups. The chickens, except blank control (BC) group, were vaccinated with Newcastle disease (ND) vaccine, repeated vaccination at 28 days old. At the same time of the first vaccination, the chickens in three SGSC groups were injected, respectively, with the SGSC at low, medium and high concentrations, in vaccination control (VC) and BC group, with equal volume of physiological saline, once a day for three successive days. On days 7, 14, 21, 28, 35 and 42 after the first vaccination, the lymphocyte proliferation, serum antibody titer and interleukin-2 (IL-2) and interferon-gamma (IFN-γ) were measured. The results showed that SGSC at suitable dose could significantly promote lymphocyte proliferation, enhance serum antibody titer, and improve serum IL-2 and IFN-γ concentrations. It indicated that SGSC could significantly improve the immune efficacy of Newcastle disease vaccine, and would be as the candidate of a new-type immune adjuvant.

Ascaridia galli infection influences the development of both humoral and cell-mediated immunity after Newcastle Disease vaccination in chickens

Potent vaccine efficiency is crucial for disease control in both human and livestock vaccination programmes. Free range chickens and chickens with access to outdoor areas have a high risk of infection with parasites including Ascaridia galli, a gastrointestinal nematode with a potential influence on the immunological response to vaccination against other infectious diseases. The purpose of this study was to investigate whether A. galli infection influences vaccine-induced immunity to Newcastle Disease (ND) in chickens from an MHC-characterized inbred line. Chickens were experimentally infected with A. galli at 4 weeks of age or left as non-parasitized controls. At 10 and 13 weeks of age half of the chickens were ND-vaccinated and at 16 weeks of age, all chickens were challenged with a lentogenic strain of Newcastle disease virus (NDV). A. galli infection influenced both humoral and cell-mediated immune responses after ND vaccination. Thus, significantly lower NDV serum titres were found in the A. galli-infected group as compared to the non-parasitized group early after vaccination. In addition, the A. galli-infected chickens showed significantly lower frequencies of NDV-specific T cells in peripheral blood three weeks after the first ND vaccination as compared to non-parasitized chickens. Finally, A. galli significantly increased local mRNA expression of IL-4 and IL-13 and significantly decreased TGF-ß4 expression in the jejunum two weeks after infection with A. galli. At the time of vaccination (six and nine weeks after A. galli infection) the local expression in the jejunum of both IFN-? and IL-10 was significantly decreased in A. galli-infected chickens. Upon challenge with the NDV LaSota strain, viral genomes persisted in the oral cavity for a slightly longer period of time in A. galli-infected vaccinees as compared to non-parasitized vaccinees. However, more work is needed in order to determine if vaccine-induced protective immunity is impaired in A. galli-infected chickens.

Cordyceps militaris polysaccharides can improve the immune efficacy of Newcastle disease vaccine in chicken

Cordyceps militaris polysaccharide (CMP) was prepared by water decoction and ethanol precipitation. The fractional CMP40 and CMP50 were extracted from the CMP solution by stepwise precipitation with ethanol at 40% and 50% of working concentration, respectively. The immune-enhancing activities of two polysaccharides were researched. In vitro experiment, the effects of two polysaccharides on chicken peripheral lymphocyte proliferation were determined by MTT assay. The result displayed that two polysaccharides could significantly stimulate lymphocyte proliferation, the action of CMP40 was significantly or numerically stronger than those of CMP50. In vivo experiment, 320 14-day-old chickens were averagely divided into eight groups. The chickens, except blank control (BC) group, were vaccinated with Newcastle disease vaccine, repeated vaccination at 28 days old. At the same time of the first vaccination, the chickens in three CMP40 fraction groups and three CMP50 fraction groups were injected respectively with the polysaccharide at low, medium and high concentrations, in vaccination control (VC) and BC group, with equal volume of physiological saline, once a day for three successive days. On days 7, 14, 21, 28, 35 and 42 after the first vaccination, the lymphocyte proliferation, serum antibody titre and interferon-gamma and interleukin-4 were measured. The results showed that CMP40 and CMP50 at suitable dose could significantly promote lymphocyte proliferation, enhance serum antibody titre, and improve serum interferon-gamma and interleukin-4 concentrations. It indicated that CMP40 fraction and CMP50 fraction could significantly improve the immune efficacy of Newcastle disease vaccine, and would be as the candidate of a new-type immune adjuvant.

Effect of oral administration of ginseng stem-and-leaf saponins (GSLS) on the immune responses to Newcastle disease vaccine in chickens

This study was designed to evaluate the effect of oral administration of ginseng stem-and-leaf saponin (GSLS) on immune responses in chickens vaccinated with live Newcastle disease (ND) vaccines. In experiment 1, chickens were orally administered GSLS (2.5, 5, 10, and 20mg/kg) in drinking water for 3 days, and then intranasally vaccinated with ND vaccine. Hemagglutination inhibition (HI) test showed that the optimal dose of GSLS for enhancing HI titers was 5mg/kg. In experiment 2, chickens were fed with GSLS (5mg/kg) for 7, 5 or 3 days before vaccination. Result indicated that GSLS enhanced HI titers in a time-dependent manner. The order of the duration for drinking GSLS on increasing HI titers was 7 days>5 days>3 days. In experiment 3, chickens were fed with GSLS before or after immunization. Serum was sampled at a week interval for 5 weeks for HI test, splenic lymphocytes were prepared at weeks 2 and 4 after the booster immunization for lymphocyte proliferation test (LPT) and intestinal tissues were sampled at week 4 after the booster immunization for immunohistochemistry and histological examination. Results showed that HI titer, LPT, IgA+ cells and intestinal intraepithelial lymphocytes (iIELs) were significantly higher in chickens drinking GSLS before vaccination than those after vaccination. Therefore, oral administration of GSLS in drinking water at a dose of 5mg/kg for 7 days significantly increased systemic as well as gut mucosal immunity in chickens immunized with ND vaccine. Considering the immune potentiating effect of GSLS on ND vaccine, GSLS should be evaluated for its oral adjuvant effect on the immune response against other diseases such avian influenza and infectious bursal disease.

Influence of Delayed Feeding on the Performance, Development and Response of Immune System to Newcastle Disease Vaccination in Chickens

The influence of delayed feeding on the performance, development and response of immun e system to Newcastle disease vaccination were investigated. 72 day old cockerel chicks purchased from a local hatchery were used. These were at the onset divided into two groups A and B of equal numbers (n = 36) and housed separately. Group A was provided with a diet containing 25% crude protein and 2800Kcal of metabolizable energy from the day of hatch while group B was deprived of feed for the first 72 h post hatch (ph) after which they were introduced to feed and thereafter maintained on same diet as group A. Onc e feeding is commenced in each of the groups, same regimen was maintained till the end of the study. Other brooding arrangements were common to the groups. 21 days ph 12 chicks were randomly selected per group, weighed, sacrificed after which two blood samples were collected for general haematology and serum biochemistry respectively. They were then necropsied and lymphoid organs as bursa of fabricius , spleen and caecal tonsil as well as liver harvested weighed and their relative weights calculated. The remaining 24 chicks per group were then vaccinated with Newcastle Disease (ND) vaccine lasota . Five days R Our results showed that delaying feeding for up to 72 h ph does not significantly affect the growth, development and function of some organs of the immune system. Moreover, it also produced no effect on Packed Cell Volume early in life as significant variation between the two groups (p<0.05) was only observed on day 47 ph. However, our finding showed that early feeding significantly improved early response to vaccinations (p<0.05) shown by higher geometric mean antibody titre. There were no differences in organ morphology and histopathology between the two groups. The study demonstrated that early feeding could be beneficial in the response of chicks to early vaccinations but does not confer other productive advantage.

Astragalus polysaccharide and oxymatrine can synergistically improve the immune efficacy of Newcastle disease vaccine in chicken

Three hundred and sixty 14-day-old chickens were divided into seven groups. The chickens, except for blank control group, were vaccinated with Newcastle disease vaccine, repeated at 28 days old. At the same time of the first vaccination, the chickens in three astragalus polysaccharide-oxymatrine (AP-OM) groups were orally administrated respectively with the mixture of AP-OM at high, medium and low concentrations, in astragalus polysaccharide (AP) group and oxymatrine (OM) group, with corresponding medicine, in non-medicine (NM) control group, with equal volume of physiological saline, once a day for 3 successive days. On 14, 21, 28, 35 and 42 days after the first vaccination, the changes of peripheral lymphocyte proliferation and serum antibody titers of the chickens were determined by MTT method and hemagglutination inhibition test. On 14, 28 and 42 days after the first vaccination, the serum IL-2 concentration was determined by Enzyme-linked Immunosorbent Assay (ELISA). The results showed that at most time points, the lymphocyte proliferation, antibody titers and IL-2 concentrations of 5 medicine-administrating groups were significantly higher than that of corresponding NM group. At some time points, the lymphocyte proliferation, antibody titers and IL-2 concentrations in high and medium doses of AP-OM groups were significantly or numberly higher than those in AP group and OM group. It indicated that AP-OM could significantly improve the immune efficacy of Newcastle disease vaccine, astragalus polysaccharide and oxymatrine possessed synergistical immunoenhancement.

Efficacy of live adjuvanted mesogenic Newcastle disease vaccine in chickens

120 white leghorn chickens primed with a lentogenic Newcastle disease (ND) live vaccine at 7 days of age were divided into three equal groups of 8 weeks of age and vaccinated with a live mesogenic ND vaccine (NDV). One group received only Newcastle disease mesogenic vaccine (RDVK) in normal saline, the second group received RDVK with groundnut oil as adjuvant and the third group received RDVK with liquid paraffin as adjuvant. Sera were collected at different time points for the assessment of antibody level against ND virus (NDV) by the haemagglutination inhibition (HI) test. The commonly used non-adjuvanted RDVK could not evince 100% protective HI titre beyond 11 weeks of age but in both the adjuvanted groups 100% protective HI titre was evident upto 20 weeks of age. On challenge at 20 weeks of age both the adjuvanted groups withstood challenge but in the non-adjuvanted group 80% of chickens withstood the challenge. A significant difference in immune response between the adjuvanted and non-adjuvanted groups was seen but not between both the adjuvanted groups. The advantage of vegetable oil (groundnut oil) as an adjuvant for live mesogenic ND vaccine has been discussed.

Impaired response to killed Newcastle disease vaccine in chicken possessing circulating antibody to chicken Anaemia agent

Broiler breeder hens from the same hatch were reared as two separate flocks, one in the field and one in experimental accommodation. Both received the same vaccination programme using the same batches of vaccines. One flock showed serological evidence of infection with chicken anaemia agent starting at 8 weeks, the other starting at 22 weeks old. Newcastle disease mean antibody titres 4 weeks after killed vaccine injected at 18 or 19 weeks old were 4.6 logs lower in the flock showing chicken anaemia agent antibody from 8 weeks old than in the flock seroconverting at 22 weeks. Three other field flocks showing poor responses to killed Newcastle disease vaccines were examined and found to be chicken anaemia agent positive when vaccinated: a further three flocks showing good Newcastle disease antibody responses were shown to be chicken anaemia agent-antibody negative. No difference in response to infectious bronchitis or infectious bursal disease killed vaccines was demonstrable between the two trial flocks. The significance of chicken anaemia agent as a potential immunosuppressive agent for chickens is discussed with special reference to the control of Newcastle disease in laying and breeding hens.