Newcastle Disease Virus Titer Research Articles

Chicken-derived MERTK protein inhibits Newcastle disease virus replication by increasing STAT1 phosphorylation in DF-1 cells

The receptor tyrosine kinases TYRO3, AXL, and MERTK (TAM) are transmembrane proteins associated with the regulation of the innate immune response. In this study, the role of the chicken-derived MERTK protein (chMertk) in the regulation of the type I interferon (IFN) signaling pathway and its antiviral effect were investigated in vitro. Newcastle disease (ND) caused by the Newcastle disease virus (NDV) is able to widely spread in chickens and give rise to massive losses in the poultry industry around the world. We found that the overexpression of the exogenous chMertk upregulated the STAT1 phosphorylation and the expression of IFN-stimulated gene IFITM3 and significantly reduced the NDV titer (p < 0.05). A mutation assay showed that three tyrosine residues (Y739, Y743, and Y744) in chMertk promoted STAT1 phosphorylation and inhibited NDV replication. However, the chicken-derived E3 ubiquitin ligase CBL significantly negatively regulated chMertk expression, thus attenuating STAT1 phosphorylation. chMertk function was restored by the ubiquitin-proteasome inhibitor MG132, demonstrating that chMertk was controlled by Casitas B-lineage proto-oncogene (CBL) ubiquitination and degradation. Together, these results suggested that chMertk participated in regulating the immune responses to NDV infection, and that CBL significantly downregulated the expression of chMertk through its ubiquitination and degradation, to maintain cellular homeostasis. Overall, our study provided new insights into the role of chMertk in regulating the innate immune response and its anti-NDV activity.

Impact of Nematode Infections on Non-specific and Vaccine-Induced Humoral Immunity in Dual-Purpose or Layer-Type Chicken Genotypes.

Nematode infections may induce immune-modulatory effects and influence host-immune responses to other pathogens. The aim of the study was to investigate whether a mixed nematode-infection influences non-specific and vaccine-induced humoral immunity against Newcastle Disease Virus (NDV), Infectious Bronchitis Virus (IBV), and Avian Metapneumovirus (AMPV) in already vaccinated hens of a dual-purpose (Lohmann Dual, LD) or a layer genotype (Lohmann Brown Plus; LB). Until 17 weeks-of-age, LD (n = 70) and LB (n = 109) hens were vaccinated against major bacterial and viral diseases and coccidiosis. At 24 weeks-of-age, the hens received either a placebo or an oral inoculation of 1,000 infectious eggs of A. galli and H. gallinarum. Plasma total immunoglobulin (Ig) isotypes (IgY, IgM, IgA) levels and vaccine-induced antibody titers against NDV, IBV, and AMPV were determined from 2 to 18 weeks post-infection (wpi). Infections had no suppressing effect on total Ig isotypes IgY, IgM, and IgA as well as on vaccine-induced antibody titers against NDV, IBV, and AMPV (P > 0.05). Overall, LB hens had higher levels of IgY, IgM, and IgA than those of LD hens (P < 0.05). There were no differences between IBV titers of the two genotypes (P > 0.05). Independent of infection status of the hens, NDV titers were higher in LB hens than in LD hens at wpi 2 (P < 0.05), but not in following weeks (P > 0.05). Uninfected LD hens had lower AMPV titers than their infected counterparts at 6 and 14 wpi (P < 0.05). Regardless of nematode infection, LD hens revealed a higher risk of responding weak to vaccination against NDV (odds ratio = 5.45; P = 0.021) and AMPV (odds ratio = 13.99, P < 0.001) than did LB hens (P > 0.05). We conclude that nematode infections have no adverse effects on non-specific and vaccine-induced humoral immunity in either genotype. LB hens have higher levels of total immunoglobulin isotypes than LD hens. Except for IBV, vaccine-induced humoral immune responses show a dependency on genotype. Dual-purpose hens show lower responsiveness to vaccinations against NDV and AMPV, possibly due to factors associated with increased body fat reserves in this genotype.

Use of Corn Silk Meal in Broiler Diet: Effect on Growth Performance, Blood Biochemistry, Immunological Responses, and Growth-Related Gene Expression.

Simple SummaryCorn silk meal (CSM), the outer thread-like material found under corn husks, is a by-product of corn cultivation, which has been documented as a traditional medicine with multiple benefits for human health. Broilers cannot produce the enzymes needed to hydrolyze non-starch polysaccharide (NSP), which has been found to increase gut viscosity, and reduce the digestion and utilization of nutrients, thereby resulting in poor animal performance. The objective of this study was to examine the effects of diets supplemented with CSM and NSP on growth performance, blood biochemistry, immunological and growth-related gene expression in broiler chickens. A total of 270 broiler chickens were divided into six experimental groups: (1) basal diets (BD) as control; (2) BD supplemented with 0.5 g/kg feed NSP enzyme; (3) and (4) fed a diet containing 40 and 80 kg/ton of CSM; (5) and (6) fed a diet containing 40 and 80 kg/ton CSM and supplemented with 0.5 g/kg NSP enzyme. The results showed that the dietary inclusion of CSM with the NSP enzyme can improve growth performance, intestinal histopathology parameters, modify plasma lipids, and enhance immune response in broilers.The objective of this study was to examine the effects of diets supplemented with corn silk meal (CSM) and non-starch polysaccharide (NSP) enzyme on growth performance, blood biochemistry, immunological response, and growth-related gene expression in broiler chickens. A total of 270 broiler chickens were divided into six experimental groups: (1) basal diets (BD) as control; (2) BD supplemented with 0.5 g/kg feed NSP enzyme; the other four groups are CSM diets as following; (3) and (4) fed diet contain 40 and 80 kg/ton of CSM; (5) and (6) fed diet contain 40 and 80 kg/ton CSM and supplemented with 0.5 g/kg NSP enzyme. Body weight gain (BWG), feed conversion ratio (FCR), protein retention and fiber digestibility were synergistically improved (p < 0.05) when fed CSM supplemented with NSP enzyme. Moreover, a synergistic decrease (p < 0.05) in the serum glucose and total cholesterol were found. Immune organ weights and Newcastle disease virus titers were increased with CSM diets. Interestingly, the relative mRNAs of the growth hormone receptor (GHR) and insulin growth factor (IGF) were increased (p < 0.05) with the CSM and NSP enzyme: the relative mRNA expressions of cholecystokinin (CCK) and leptin were decreased by feeding CSM diets with the NSP enzyme. It could be concluded that the dietary inclusion of CSM with the NSP enzyme might improve growth performance, modify plasma lipids, and enhance immune response in broilers.

Supplementation of a water-soluble zinc-AA complex to reduce stress in broilers, pullets, and layers1.

This study consisted of three 5-wk experiments to test the effects of administering Zinpro-LQ (Zinpro-LQ, Zinpro Corporation, Eden Prairie, MN) for different time intervals in stressed broilers, pullets, and layers. Treatments included: nonstressed control (NC), stressed control (SC), stressed and supplemented Zinpro-LQ for 14 d prior to stressor (S1), 10 d prior (S2), 7 d prior to and 7 d during stressor (S3), and 5 d prior (S4). Birds included 1-d-old Cobb 500 male broilers (Experiment 1), 7-wk-old white Leghorn pullets (Experiment 2), and 50-wk-old white Leghorn layers (Experiment 3). All stressed birds were vaccinated against Newcastle Disease Virus (NDV) on day 28 and exposed to random feed and water withdrawal days 28 to 35 for 6 h/d. Pullets were beak trimmed on day 21, and layers were heat stressed days 28 to 35. Blood was sampled on day 35 to determine plasma chemistry, corticosterone (CORT), anti-NDV antibody titer, and heterophil/lymphocyte (H/L) ratio. Mortality, feed and water consumption, and BW were also recorded. In Experiment 1, CORT and H/L ratio were highest in SC (P < 0.05). In Experiment 2, CORT was higher in SC than S4 (P < 0.05) while all other treatments were statistically intermediate. NDV titer was lower in SC than S4 while all other treatments were statistically intermediate. Treatment differences were also observed for H/L ratio, and plasma uric acid and cholesterol in Experiment 2. In Experiment 3, treatment differences were observed for H/L ratio, plasma glucose, sodium, and chloride. H/L ratio was lower in NC, S1, and S4 compared with SC (P < 0.05); and NC and S1 were lower than S2 (P < 0.05). In conclusion, dietary inclusion of zinc AA complex for any length of time prior to a stressor helped reduce measures of stress in broilers. The S1 and S4 treatments helped reduce stress and improve humoral immune response in pullets and layers.

Effects of beta-1,3-glucan (AletaTM) on vaccination response in broiler chickens

This 42-day study evaluated the effects of dietary supplementation with β-1,3-glucan (Aleta™) on the vaccination response to Newcastle disease virus (NDV), avian infectious bronchitis virus (IBV), and infectious bursal disease (IBD) in a non-challenged environment. This trial included 600 chicks (all vaccinated with IBD at the hatchery) which were assigned to 1 of 3 treatments: vaccination (NDV, IBV), no vaccination, or vaccination combined with feed supplemented with Aleta (100 g/MT of feed). The vaccination with Aleta treatment group showed a trend for improved FCR that was not statistically significant. Control birds that were not vaccinated for IBV had significantly lower IBV titers on day 21 compared to birds that were vaccinated (both with and without Aleta). Surprisingly, there was significant separation among treatment groups for NDV titer levels, especially on day 21, where birds vaccinated and supplemented with Aleta had significantly higher titer levels compared to vaccination alone or no vaccination at all. Critically, only 14% of the birds receiving the vaccine plus Aleta had titer levels below the critical titer threshold for immunity compared to 28% of the birds receiving the vaccine alone and 40% of the unvaccinated birds. This suggests that Aleta supplementation may help to improve the vaccination response by birds, especially for NDV.

Effect of Newcastle disease virus level of infection on embryonic length, embryonic death, and protein profile changes.

Background and Aim:Newcastle disease virus (NDV) is an obligate intracellular parasite. Virus can only live on living cells. The embryonated chicken eggs (ECEs) are one of the growth media of virus that is a cheap, easy to do, and accurate for showing patterns of virus change in the host. Higher virus titers indicate the higher number of viruses and more virulent to infect host. This research aimed to investigate the effect of different level of NDV titer infection in ECEs on protein profile, embryonic length, mortality, and pathological change.Materials and Methods:The study used a completely randomized design of six treatments and seven replications. The treatments were different level of NDV titer infection in allantoic fluid (AF) of 9-11 days ECEs, i.e., P1=20, P2=26, P3=27, P4=28, P5=29, and P6=210 hemagglutination unit (HAU). All samples were separated by sodium dodecyl sulfate-polyacrylamide gel electrophoresis. Data were analyzed using one-way ANOVA with p=0.05 for length of the embryo and descriptive analysis for embryo mortality, pathology change, and protein band.Results:The result showed that protein profile of NDV-infected ECEs of all different levels is more complex than protein profile of no NDV-infected ECEs. NDV infected of all different levels showed longer size embryo, higher mortality embryo at the first 2 days, and higher occurrence of hemorrhagic in all part of bodies of embryo than those of no NDV infected.Conclusion:It was concluded that NDV infection of all different level decreased health conditions of chicken embryo of ECEs of 9-11 days old. Different level of NDV infection of ECEs of 9-11 days old showed no significantly different embryo profiles. However, all of the NDV-infected embryos were shorter, death on the 2nd day, and suffered more hemorrhage on all body surfaces than uninfected NDV embryos.

Enhanced pathogenicity of low-pathogenic H9N2 avian influenza virus after vaccination with infectious bronchitis live attenuated vaccine.

Aim:In the present study, two experiments were carried out for studying the pathogenicity of H9N2 avian influenza virus (AIV) in broiler chickens after vaccination with different live respiratory viral vaccines.Materials and Methods:One-day-old specific pathogen-free (SPF) chicks were divided into four groups in each experiment. In experiment 1, Groups 1 and 2 were inoculated with H9N2 AIV through nasal route in 1 day old, Groups 1 and 3 were vaccinated with live infectious bronchitis coronavirus (IBV) vaccine in 5 days old, and Group 4 was left as a negative control. In experiment 2, Groups 5 and 6 were inoculated with AIV subtype H9N2 through nasal route in 1 day old, Group 5 was vaccinated with live IBV vaccine and live Newcastle disease virus (NDV) vaccine in 5 and 18 days old, respectively, Groups 6 and 7 were vaccinated with live NDV vaccine in 18 days old, and Group 8 was left as a negative control. Chicks were kept in isolators for 18 days in the first experiment and 35 days in the second experiment. Tracheal and cloacal swabs were collected from 3, 5, 7, 10, 12, and 15 day’s old chicks from all groups in experiment 1 and 21, 23, 25, and 28 days old from all groups in experiment 2. Quantitative real-time reverse-transcriptase polymerase chain reaction (rRT-PCR) was applied on the collected tracheal swabs for detecting RNA copies of H9N2 AIV. Cloacal swabs and the positive rRT-PCR tracheal swabs were inoculated in 10-day-old SPF embryonated chicken eggs (ECE) to confirm rRT-PCR results. Internal organs (kidney, trachea, and spleen) from all chicken groups were collected weekly for histopathological examination to determine severity of the lesions. Serum samples were collected on a weekly basis for the detection of humoral immune response against H9N2, NDV, and IBV from all chicken groups.Results:rRT-PCR results with virus titration in ECEs revealed a significant increase in H9N2 AIV titer with extension in the period of viral shedding in Groups 1 and 5. Severe lesion score was observed for Groups 1 and 5. The humoral immune response against H9N2 AIV, NDV, and IBV revealed a significant increase in H9N2 AIV titer in Groups 1 and 5, NDV titer showed a significant increase in Group 7, and IBV titer increased in Groups 1, 3, and 5.Conclusion:Results demonstrated the increase in pathogenicity of H9N2 AIV, especially when H9N2-infected chicks vaccinated with live IBV vaccine.

Enhanced Replication of Virulent Newcastle Disease Virus in Chicken Macrophages Is due to Polarized Activation of Cells by Inhibition of TLR7.

Newcastle disease (ND), caused by infections with virulent strains of Newcastle disease virus (NDV), is one of the most important infectious disease affecting wild, peridomestic, and domestic birds worldwide. Vaccines constructed from live, low-virulence (lentogenic) viruses are the most accepted prevention and control strategies for combating ND in poultry across the globe. Avian macrophages are one of the first cell lines of defense against microbial infection, responding to signals in the microenvironment. Although macrophages are considered to be one of the main target cells for NDV infection in vivo, very little is known about the ability of NDV to infect chicken macrophages, and virulence mechanisms of NDV as well as the polarized activation patterns of macrophages and correlation with viral infection and replication. In the present study, a cell culture model (chicken bone marrow macrophage cell line HD11) and three different virulence and genotypes of NDV (including class II virulent NA-1, class II lentogenic LaSota, and class I lentogenic F55) were used to solve the above underlying questions. Our data indicated that all three NDV strains had similar replication rates during the early stages of infection. Virulent NDV titers were shown to increase compared to the other lentogenic strains, and this growth was associated with a strong upregulation of both pro-inflammatory M1-like markers/cytokines and anti-inflammatory M2-like markers/cytokines in chicken macrophages. Virulent NDV was found to block toll-like receptor (TLR) 7 expression, inducing higher expression of type I interferons in chicken macrophages at the late stage of viral infection. Only virulent NDV replication can be inhibited by pretreatment with TLR7 ligand. Overall, this study demonstrated that virulent NDV activates a M1-/M2-like mixed polarized activation of chicken macrophages by inhibition of TLR7, resulting in enhanced replication compared to lentogenic viruses.

Evaluation of the effect of live LaSota Newcastle disease virus vaccine as primary immunization on immune development in broilers

Newcastle disease remains a major concern to the poultry industry; however, it can be managed with effective vaccination programs. The main objective of this study was to evaluate the effect of 2 1× doses of live LaSota strain Newcastle disease virus (NDV) vaccine administered oculo-nasally on d one and 21 on development of humoral and cell-mediated immune response in broilers, and to compare different immunization schedules. Two experiments were conducted. In Experiment I (n = 320), Ross 308 birds were randomly assigned to an unvaccinated control group or vaccinated treatment. [Both treatments consisted of 4 pens per treatment and 40 birds per pen]. At d one, live NDV LaSota strain vaccine was used as a primary immunization to evaluate its impact on adaptive immunity. No substantial NDV-specific humoral immune response was established. Body weights were significantly higher (P < 0.05) in the vaccinated birds on d 4 and 7. Spleen index of the vaccinated birds was significantly (P < 0.05) lower at d 28 and 35. Flow cytometry showed reduced levels of peripheral and splenic B and T lymphocytes. Interferon gamma secreted by splenocytes and in circulation was measured; the results showed a reduced expression post-secondary immunization. In Experiment II (n = 180), the role of maternal antibodies and primary vaccination at d one was evaluated using 3 vaccination protocols. Protocol 1 used live B1 strain as primary immunization, whereas protocol 2 used live LaSota strain. Protocol 3 used live LaSota strain after maternal antibodies had decayed. Protocol 3 resulted in the highest NDV-titer level during the trial. Protocol 2 had the lowest NDV titer. Feed conversion was significantly higher (P < 0.05) in protocol 3 compared to 1 and 2. Overall, the results indicate that the use of live LaSota strain NDV vaccine as primary immunization at d one has a detrimental effect on the development of adaptive immunity in broilers; however, its use after the level of maternal antibodies decays results in a robust antigen-specific humoral immune response.

Efficacy of Supplementing Ashwgandha Extract (Withania somnifera) on Immunity and Serum Biochemitry in Broilers During Summer

The objective of present study was to determine the effects of different levels of Ashwagandha (Withania somnifera) extract (WSE) on immunity and serum biochemical parameters of broiler chicken reared during hot summer. The average minimum and maximum room temperatures recorded from 0-42 day were 36.8oC±0.25 – 39.7oC±0.25, respectively, with relative humidity ranging from 47 – 74%. Day old broiler chicks (n=160) were randomly allotted to 4 dietary groups with eight replicates of five birds each. The four groups were Positive control (PC) with vit-E (70mg/kg) +Se (0.15mg/kg), Negative control (NC), WSE50 and WSE100 groups supplemented with WSE 50mg/kg and 100mg/kg, respectively. Serum cholesterol levels were significantly (P0.05) by supplementation of WSE. Humoral immune response in terms of NDV (Newcastle disease virus) titer and cell mediated immunity in terms of cutaneous basophilic hypersensitivity (CBH) were not significantly influenced by supplementation of WSE in broiler diets.

Intracellular fixation buffer inactivates Newcastle disease virus in chicken allantoic fluid, macrophages and splenocytes

Inactivation of Newcastle disease virus (NDV) has been routinely achieved with heat, β-propiolactone, binary ethylenimine, ultraviolet light and formalin. However, these strategies have not been tested for cell surface ligand or receptor phenotype in viral-infected chicken immune cells. To study the capacity of fixation buffers to preserve surface markers while inactivating NDV, a primary splenocyte culture was infected with NDV and incubated with a commercial intracellular fixation buffer (ICB), formulated with 4% formaldehyde. Splenocytes were fixed with a 1:2 dilution of ICB in phosphate buffered saline (PBS) for 45min at 23°C or 4°C and inactivation of NDV was tested in addition to recognition of antigens by antibodies in fixed and non-fixed splenocytes via flow cytometric analysis. The binding and percentage of splenic CD4+ and CD8+ cells were not affected. In addition, NDV titers as high as 109.5 and 107.6 EID50 in allantoic fluid (AF) and macrophages, respectively, were successfully inactivated after 45min at 23°C and 4°C, confirming the ICB’s effectiveness in inactivating high concentrations of NDV. In conclusion, high concentrations of NDV in AF, chicken splenocytes, and macrophages can be inactivated using ICB. Additionally, this method did not compromise cell phenotyping of enriched chicken splenocytes.

Immunomodulatory effects of Newcastle disease virus AF2240 strain on human peripheral blood mononuclear cells.

Immunotherapy has raised the attention of many scientists because it hold promise to be an attractive therapeutic strategy to treat a number of disorders. In this study, the immunomodulatory effects of low titers of Newcastle disease virus (NDV) AF2240 on human peripheral blood mononuclear cells (PBMC) were analyzed. We evaluated cytokine secretion and PBMC activation by cell proliferation assay, immunophenotyping and enzyme linked immunosorbent assay. The proliferation of the human PBMC was measured to be 28.5% and 36.5% upon treatment with 8 hemaglutinin unit (HAU) and 2 HAU of NDV respectively. Interestingly, the percentage of cells with activating markers CD16 and CD56 were increased significantly. Furthermore, the intracellular perforin and granzyme levels were also increased upon virus infection. Human PBMC treated with NDV titer 8 HAU was found to stimulate the highest level of cytokine production including interferon-γ, interleukin-2 and interleukin-12. The release of these proteins contributes to the antitumor effect of PBMC against MCF-7 breast cancer cells. Based on the 3-(4, 5-dimethylthiazol-2-yl)-2, 5-diphenyl tetrazolium bromide assay, activated human PBMC showed high cytolytic efficiency towards human breast tumor cells. In summary, NDV was able to stimulate PBMC proliferation, cytokine secretion and cytolytic activity.

Interactions between escherichia coli and Newcastle disease virus in chickens.

We investigated the interaction between Newcastle disease virus (NDV) and Escherichia coli in cell cultures, embryonated eggs, and 8-wk-old chickens. We measured the interactions on the basis of bacterial adherence and NDV hemagglutination titer in chickens, chicken embryos, and chicken embryo cell culture. Depending on the inoculation order of E. coli, a significant alteration of the growth of NDV was observed in both chickens and chicken embryos. When certain strains of E. coli were given before NDV exposure, the virus titers were lowered. In chickens, the mean virus titer was significantly (P < 0.05) lowered in the crop, the proventriculus, the gizzard, and the jejunum. However, there were no significant differences (P < 0.05) between the two groups for NDV titers in the duodenum, ileum, and cecum. In chicken embryos, when E. coli serotypes O78 and O119:B14 were inoculated before NDV exposure, the mean NDV titers were significantly (P < 0.5) lowered. However, there were no significant differences (P < 0.05) in NDV titer between the two groups when E. coli serotypes O78:K80:NM and O1ab:K NM were inoculated 24 hr before NDV exposure. When NDV was given prior to E. coli exposure, NDV titer was higher in both chickens and chicken embryos. In chickens, when NDV was given 48 hr before E. coli inoculation, NDV was detected in the proventriculus, gizzard, jejunum, ileum, and cecum, whereas no virus was detected in the control groups (NDV only). In the crop, NDV was detected at a significantly (P < 0.05) higher titer in the E. coli-inoculated group when compared with the control group that received NDV alone. In chicken embryos, virus titer was significantly (P < 0.05) higher when NDV was given 24 hr before E. coli inoculation for all three NDV strains used (Ulster and V4 strains). Adherence of E. coli to chicken embryo kidney (CEK) cells was significantly higher (P < 0.05) when the CEK cells were infected first with NDV and then by E. coli. The mean bacterial count per microscopic field in NDV-uninfected monolayers was eight compared with 112 for the NDV-infected monolayers. In approximately 10% of the fields in NDV-infected monolayers, the bacteria were too numerous to count.

The Interaction between Newcastle Disease Virus and Escherichia coli Endotoxin in Chickens

The interaction between Newcastle disease virus (NDV) and Escherichia coli endotoxin was studied in cell cultures, embryonated chicken eggs, and 8-wk-old chickens. These interactions were evaluated according to the induction of specific or nonspecific resistance in the host system and the virus titer produced in both chicken embryos and chickens. The endotoxin of E. coli induced a decrease in the size of the bursa of Fabricius in live chickens. Escherichia coli endotoxin given intravenously induced plasma antiviral activity in chickens that was interpreted to be interferon, as detected in a vesicular stomatitis virus plaque reduction assay. Endotoxin failed to produced toxic effects in the chicken embryo fibroblasts (CEFs) or to result in any antiviral effect because no change was noted in the number of NDV plaques formed in CEF cultures. When endotoxin was given 3 days before NDV exposure in chickens, the virus titers were significantly (P < 0.05) decreased from a peak of 10(2) to 10(0.18), 10(2.5) to 10(0.18), and 10(2.5) to 0 in the spleens, lungs, and kidneys, respectively, at 72 hr post-NDV inoculation. When endotoxin was given 24 hr after NDV inoculation, the NDV titer significantly (P < 0.05) increased from 10(2.0) to 10(3.5), 10(2.5) to 10(6.5), 10(2.5) to 10(4.5), 0 to 10(2.5) in the spleen, lungs, kidneys, and liver, respectively, at 72 hr after NDV inoculation. In chicken sera, hemagglutination inhibition (HI) titer to NDV was significantly (P < 0.05) enhanced from 1164 to 3127 when endotoxin was given prior to virus inoculation. However, there was a decrease in HI to NDV from 1164 to 727 without a significant difference in chicken sera when NDV was given prior to endotoxin inoculation.

Cell-Mediated and Humoral Immune Responses in Chickens Infected with Salmonella typhimurium

The cellular immune responses of leghorn and New Hampshire chickens following oral challenge at 4 weeks of age with Salmonella typhimurium were measured using assays for lymphocyte proliferative responses to mitogens and cytotoxic activity of natural killer (NK) cells. In addition, the humoral immune response to Newcastle disease virus (NDV) vaccine was assessed in S. typhimurium-infected chickens. At 8 and 20 days after infection with S. typhimurium, lymphocyte proliferative responses to various mitogens were significantly higher in S. typhimurium-infected chickens than in uninfected birds of the same breeds. Cytotoxic activity of NK cells was also significantly increased in infected birds on these days. Thirteen days after S. typhimurium infection, infected NDV-vaccinated chickens had higher antibody titers in response to NDV vaccination than uninfected vaccinated birds. NDV titers did not differ among groups at any other time of testing. These results show that both cellular and humoral immune functions are activated in the first 3 weeks following infection of 4-week-old chickens with S. typhimurium.

Immune Response to Newcastle Disease Virus Vaccine, Fowl-Pox Vaccine, and Escherichia coli Vaccine in Bedouin and White Leghorn Chickens

Immune response to Newcastle disease virus (NDV) vaccine, fowl pox, and E. coli vaccine was compared in the native Bedouin fowl of the Sinai desert, in a commercial Leghorn layer strain, and in the reciprocal crosses between them. Differences were not found in antibody titer levels to attenuated or inactivated NDV vaccines, in the proportion of birds showing post-vaccination immunity to fowl pox, or in the kinetics of postvaccination NDV titer levels. Rate of development of titer to Escherichia coli from day 1 to day 4, however, was significantly more rapid in Bedouin chicks than in the purebred Leghorn or the reciprocal crosses.

Aerosol Vaccination against Newcastle Disease III. Field Experiments in Broiler Chickens

Two different aerosol generators were used for aerosol-vaccination of 128,000 broiler-type chickens having moderate to low maternal antibody titers with the B1 and LaSota strains of Newcastle disease virus (NDV). Efficacy of vaccination was evaluated from resistance to challenge with a velogenic strain (Texas GB) of NDV and hemagglutination-inhibition (HI) antibody titers, Both aerosol generators induced adequate immune response at the aperture settings used. There was little detectable benefit from vaccination at 1 day old, but antibody response and resistance to challenge were good from vaccination at 10 and 28 days of age.