Differential immunomodulatory effect of vitamin D (1,25 (OH)2 D3) on the innate immune response in different types of cells infected in vitro with infectious bursal disease virus.

It has been demonstrated that vitamin D (Vit D) included in diets offers a beneficial effect by improving innate immune responses in chickens. However, its mechanisms of action and the effect on immunosuppressive pathogens, such as infectious bursal disease virus, are not yet known. In the present study, we have studied the immunomodulatory effect of Vit D on the innate immune response in 3 cell lines: fibroblast cells (DF-1), macrophages (HD11), and B cells (DT-40) infected with IBDV (intermediate vaccine) at 2 multiplicity of infections (MOI) (1 and 0.1). Genes associated with innate immune responses (TLR-3, TLR-21, MDA-5, MyD88, TRIF, IRF-7, INF-α, INF-ß, PKR, OAS, viperin, IL-1ß, IL-6, and IL-12) were evaluated at different time points (3, 6, 12, 24, and 36 h after infection, h.p.i). Virus production reached a maximum at 24 h.p.i., which was significantly (P < 0.05) higher in DF-1 cells, followed by HD-11 and DT-40 cells. Mainly in HD-11 cells, there was a significant (P < 0.05) effect of Vit D supplementation on receptors TLR-3, TLR-21, and MDA-5 after 12 h.p.i, independent of MOI. DT-40 cells showed the highest antiviral activity, with a significant (P < 0.05) effect on IRF-7, IFN-ß, OAS, and PKR gene expression, where expression of IRF-7 and IFN-ß correlated positively with Vit D supplementation, while OAS and PKR were independent of Vit D. Proinflammatory cytokines were significantly (P < 0.05) upregulated and found to be Vit D and MOI dependent. In conclusion, this study demonstrated the capacity of IBDV to trigger a strong innate immune response in chicken cells and contributes to the understanding of the activation pathways of innate immunity induced by IBDV and further shows the benefitial effect of Vit D supplementation as an immunomodulator.

Stinging nettle and neem enhance antibody response to local killed and imported live infectious bursal disease vaccines in indigenous chicken in Kenya.

Immune responses are critical for protection of chickens from infectious bursal disease (IBD). In this study, the antibody response-enhancing effect of drinking water supplementation of 1% stinging nettle and neem on different IBD vaccines and vaccination regimes was evaluated, using 36 (n = 36) specific antibody negative indigenous chicks. The birds were allocated into 3 groups as follows: 1A-C, 2A-C, and 3A-B, while group 3C acted as the unvaccinated non-supplemented control. A local inactivated K1 and imported live attenuated D78 IBD vaccines were given to groups 1A-C and 3A-B at 14 and 28 d of age, respectively. A combination of K1 and D78 vaccines was given 30 d apart to groups 2A and 2B (D78 at 14 and 21 d and K1 at 44 d of age) and on the same d to group 2C at 14 and 28 d of age. Stinging nettle was given in water to groups 1B, 2B, and 2C, and neem to groups 1C, 2A, and 3B. Birds were bled weekly and immune responses monitored using indirect ELISA. Both neem and stinging nettle had antibody response-enhancing effects in groups 1B and 1C, receiving the local inactivated K1 vaccine. There were significant differences (P < 0.05) in antibody titers between groups 1A and 2C. Stinging nettle induced earlier onset of high antibody responses in group 2C and persistent titers (>3.8 log10) from the third week in group 2B. Imported live D78 vaccine induced higher antibody titers compared to the local inactivated K1 vaccine. Groups 2B and 2C receiving a combination of the local K1 and imported live attenuated D78 vaccines had the highest antibody titers. Adoption of stinging nettle supplementation and a prime-boost program involving use of a local virus isolates-derived vaccine is recommended.

Dietary L-arginine modulates immunosuppression in broilers inoculated with an intermediate strain of infectious bursa disease virus.

BACKGROUND: The effects of dietary l-arginine (Arg) on immunosuppression following infectious bursal disease virus (IBDV) inoculation in broiler chickens were evaluated. The design of this study was a 5 × 2 factorial arrangement (n = 5) with five Arg concentrations (starter: 9.9, 13.9, 17.6, 21.3 and 25.3 g kg(-1) ; grower-finisher: 9.5, 13.5, 17.1, 20.1 and 23.6 g kg(-1) ) with or without IBDV inoculation (IBDV or saline inoculation at 14 days). Chickens were sampled at 2, 4 and 6 days post-inoculation (DPI) and 42 days of age. RESULTS: The IBDV inoculation decreased (P = 0.05) CD3(+) , CD4(+) , and CD8(+) T cell counts at 2 days post-inoculation (DPI) and monocyte counts at 6 DPI; and reduced (P < 0.05) bursal interleukin-1ß (IL-1ß) mRNA expression at 2 DPI and serum IL-6 concentration at 4 DPI. Increasing Arg concentration increased (P < 0.05) CD4(+) and CD8(+) T cell counts at 2 DPI, linearly increased (P = 0.05) CD3(+) T cell counts in IBDV-inoculated groups and monocyte counts in control groups at 4 DPI; increased (P < 0.05) serum IL-6 concentration in IBDV-inoculated groups at 2 DPI; and increased (P < 0.05) serum anti-IBDV antibody titres at 42 days of age. CONCLUSION: Varying concentrations of Arg supplementation attenuated IBDV inoculation induced immunosuppression via modulating circulating T cell sub-populations.

Effect of dietary combination of methionine and fish oil on cellular immunity and plasma fatty acids in infectious bursal disease challenged chickens.

This study was carried out to investigate the modulatory effects of dietary methionine and fish oil on immune response, plasma fatty acid profile, and blood parameters of infectious bursal disease (IBD) challenged broiler chickens. A total of 300 one-day-old male broiler chicks were assigned to one of six dietary treatment groups in a 3 × 2 factorial arrangement. There were three levels of fish oil (0, 2.5 and 5.5%), and two levels of methionine (NRC recommendation and twice NRC recommendation). The results showed that the birds fed with 5.5% fish oil had higher total protein, white blood cell count, and IL-2 concentration than those of other groups at 7 days after IBD challenge. Inclusion of fish oil in diet had no effect on IFN- γ concentration. However, supplementation of methionine twice the recommendation enhanced the serum IFN- γ and globulin concentration. Neither of fish oil nor methionine supplementation affected the liver enzymes concentration. It can be suggested that a balance of moderate level of fish oil (2.5%) and methionine level (twice NRC recommendation) might enhance immune response in IBD challenged broiler chickens.

Effects of Dangguibuxue Tang, a Chinese herbal medicine, on growth performance and immune responses in broiler chicks.

The effects of Dangguibuxue Tang (DBT) on growth performance and immunity response in immunosuppressed broiler chicks were investigated in this study. 240 one-d-old broiler chicks (DaHeng S01) were randomly divided into 4 groups, 2.0% DBT-treatment (A), 0.5% DBT-treatment (B), cyclophosphamide-control (C), and control group (D). From 4 d to 7 d of age, chicks in group A, B and C were given cyclophosphamide (CY) at a dosage of 100mg/kg body weight (BW) daily by intraperitoneal injection to induce immunosuppression. Chicks in group D were given an equal volume of physiological saline daily by intraperitoneal injection and considered normal chicks. Groups A and B were supplemented with 2.0% or 0.5% of DBT in the drinking water from 8 d to 42 d of age. Groups C and D did not receive any additional medication. The results revealed that chicks from group B had lower feed:gain rate (FGR), lower total mortality, higher immunity organ indexes, higher levels of Newcastle disease (ND) antibody and infectious bursal disease (IBD) antibody, higher interleukin-2 and interleukin-6 levels, and greater lymphocyte proliferative responses to concanavalin A (ConA) during the experiment than those from group C. However, no significant difference in the immunity status in the two levels of DBT-treatment was observed. These results indicate that supplementation of 0.5% of DBT can improve both cellular immunity and humoral immunity in immunosuppressed broiler chicks.

Effects of Dangguibuxue Tang, a Chinese herbal medicine, on growth performance and immune responses in broiler chicks

The effects of Dangguibuxue Tang (DBT) on growth performance and immunity response in immunosuppressed broiler chicks were investigated in this study. 240 one-d-old broiler chicks (DaHeng S01) were randomly divided into 4 groups, 2.0% DBT-treatment (A), 0.5% DBT-treatment (B), cyclophosphamide-control (C), and control group (D). From 4 d to 7 d of age, chicks in group A, B and C were given cyclophosphamide (CY) at a dosage of 100mg/kg body weight (BW) daily by intraperitoneal injection to induce immunosuppression. Chicks in group D were given an equal volume of physiological saline daily by intraperitoneal injection and considered normal chicks. Groups A and B were supplemented with 2.0% or 0.5% of DBT in the drinking water from 8 d to 42 d of age. Groups C and D did not receive any additional medication. The results revealed that chicks from group B had lower feed:gain rate (FGR), lower total mortality, higher immunity organ indexes, higher levels of Newcastle disease (ND) antibody and infectious bursal disease (IBD) antibody, higher interleukin-2 and interleukin-6 levels, and greater lymphocyte proliferative responses to concanavalin A (ConA) during the experiment than those from group C. However, no significant difference in the immunity status in the two levels of DBT-treatment was observed. These results indicate that supplementation of 0.5% of DBT can improve both cellular immunity and humoral immunity in immunosuppressed broiler chicks.

Omega-3 polyunsaturated fatty acids enrichment alters performance and immune response in infectious bursal disease challenged broilers.

BACKGROUND: Infectious bursal disease (IBD) results in economic loss due to mortality, reduction in production efficiency and increasing the usage of antibiotics. This study was carried out to investigate the modulatory roles of dietary n-3 polyunsaturated fatty acids (PUFA) enrichment in immune response and performance of IBD challenged broiler chickens. METHODS: A total of 300 day old male broiler chicks were assigned to four dietary n-3 PUFA ascending levels as the treatment groups (T1: 0.5; T2: 8.0; T3: 11.5; T4: 16.5) using combinations of tuna oil and sunflower oil. All diets were isocaloric and isonitrogenous. On day 28, all birds were challenged with IBD virus. Antibody titer, cytokine production, bursa lesion pre and post-challenge and lymphoid organ weight were recorded. RESULTS: On d 42 the highest body weight was observed in the T2 and T3 and the lowest in T4 chickens. Feed conversion ratio of the T2 broilers was significantly better than the other groups. Although productive parameters were not responded to the dietary n-3 PUFA in a dose-dependent manner, spleen weight, IBD and Newcastle disease antibody titers and IL-2 and IFN-γ concentrations were constantly elevated by n-3 PUFA enrichment. CONCLUSIONS: Dietary n-3 PUFA enrichment may improve the immune response and IBD resistance, but the optimum performance does not coincide with the optimum immune response. It seems that dietary n-3 PUFA modulates the broiler chicken performance and immune response in a dose-dependent manner. Thus, a moderate level of dietary n-3 PUFA enrichment may help to put together the efficiency of performance and relative immune response enhancement in broiler chickens.

Hypericum perforatum extract therapy for chickens experimentally infected with infectious bursal disease virus and its influence on immunity.

Hypericum perforatum extract (HPE) has been proved a drug effective to many viral diseases. The purpose of this paper was to investigate the therapeutic efficacy and immuno-enhancement of HPE for chickens which were already challenged with infectious bursal disease virus (IBDV BC-6/85). Chickens infected with IBDV were treated with HPE for 5 consecutive days, the observation of immune organ indexes and pathological changes index, determination of IFN-α and detection of IBDV with RT-PCR were employed to assess in vivo whether or not HPE had the certain therapeutic efficacy on infectious bursal disease (IBD), and if HPE was able to improve the immunologic function. The results showed that 1330 and 667.9 mg/kg body weight (BW) per day of HPE had significant therapeutic efficacy and improvement immunologic functions for chickens infected experimentally with IBDV.

Conjugated linoleic acids alleviate infectious bursal disease virus-induced immunosuppression in broiler chickens.

The immunoregulatory actions of conjugated linoleic acid (CLA) of relevance to viral disease pathogenesis and immune responses were investigated. To test the hypothesis that CLA ameliorates immunosuppression, we developed a viral challenge model by infecting chickens with infectious bursal disease virus (IBDV). After 14 d of dietary supplementation with either soybean oil or CLA, half of the chickens in each group were challenged with IBDV. We examined the effect of CLA on the development of lesions (i.e., lymphoid depletion and necrosis) and observed the immune responses against IBDV. The IBDV infection depleted lymphocytes in the medullary area and significantly stimulated interferon (IFN)-γ and IL-6 mRNA relative expression of bursa (P < 0.05) compared with the uninfected bursa. Compared with the CLA diet, lymphocytes depletion was more accentuated in chickens fed the control diet, whereas IFN-γ and IL-6 mRNA relative expression were upregulated (P < 0.05). Additionally, histopathological examination of the bursa revealed that the pathological changes tended to be more severe in infected chickens fed the control diet, which also significantly decreased (P < 0.05) on lymphocyte proliferation. Significant interactions were found between infection and diets for lymphocyte proliferation, antibody titers, and IFN-γ mRNA relative expression (P < 0.05). The results of this study indicate that dietary CLA enhanced immune function in chickens, particularly those of the IBDV-immunosuppressive status. Furthermore, at the molecular level, the immunoregulatory functions of CLA on chickens are attributable mainly to the antiinflammatory properties of CLA and are mediated, at least in part, through suppressing IBDV-specific proinflammatory cytokines mRNA relative expression.

Enhancement of immune responses to infectious bursal disease vaccine by supplement of an extract made from Momordica cochinchinensis (Lour.) Spreng. seeds.

The immunological effect of an extract from Momordica cochinchinensis seed (ECMS) on immune responses against infectious bursal disease (IBD) in chickens was evaluated. Fifty-two birds were equally divided into 4 groups and immunized with inactivated IBD vaccine alone (controls) or IBD vaccine emulsified with ECMS (20, 40, and 80 microg). Serum IgG antibody levels against IBD and BW were measured on 0, 7, 14, 21, 28, and 35 d after immunization. The ELISA results revealed that the chickens that received 20 microg of ECMS had significantly enhanced antibody levels on 14, 21, 28, and 35 d when compared with controls (P<0.05). A significant increase in mitogenic stimulated lymphocyte proliferation was also recorded in all ECMS groups as compared with controls (P<0.05; P<0.01). No adverse effect of ECMS was noted on growth performance, although average weight gain was significantly higher in 20 microg (7, 14, 21, 28, and 35 d) and 40 or 80 microg (14 d) of ECMS groups as compared with controls (P<0.05; P<0.01). Further studies are suggested for the investigation of immunological effects of ECMS.

Arginine and vitamin E improve the antibody responses to infectious bursal disease virus (IBDV) and sheep red blood cells in broiler chickens.

1. Dietary arginine (ARG) and vitamin E (VE) have been shown to improve immune responses in broiler chickens, but their combined effects have not been well documented. The objective of this study was to evaluate the combined effects of dietary ARG and VE on antibody responses to sheep red blood cell (SRBC, agglutination assay) inoculation in 13-d-old chicks, and antibody titres (ELISA) to infectious bursal disease virus (IBDV) before and after vaccination of 20-d-old chicks. 2. One-day-old broiler chicks were fed diets with normal (NARG, 12 g/kg of feed) or high (HARG, 22 g/kg of feed) inclusion rates of ARG, and three rates of VE (40, 80, or 200 mg/kg of feed; 40 mg being the supplement used in commercial diets) in a factorial arrangement. 3. Antibody titres to SRBC at 5, 8, and 12 d after inoculation were higher in chicks fed on the HARG diet than in those on NARG, and in chickens on VE80 compared with those on VE200 at 5, 8, and 12 d after inoculation. Antibody titres to the IBDV 2 days before and 19 d after vaccination were higher in chickens on HARG compared with those on NARG, and in chicks on VE80 compared to those on VE40 but similar to those on VE200. Conversely, 5 d after vaccination titres against IBDV were higher in chicks on NARG than in those on HARG, and in chickens on VE40 compared with those on VE80, yet similar to those on VE200. 4. These results show that diets with high ARG and high VE (80 mg/kg) improved the humoral-mediated immune response of broilers to IBDV and SRBC, suggesting it could be a strategy to improve vaccination protection and resistance to diseases.

Effects of a multi-strain probiotic (PrimaLac) on performance and antibody responses to Newcastle disease virus and infectious bursal disease virus vaccination in broiler chickens.

The effects of the probiotic PrimaLac (Lactobacillus acidophilus, Lactobacillus casei, Enterococcus faecium and Bifidobacterium bifidium) was investigated on performance and immune responses to vaccination against Newcastle disease and infectious bursal disease in broiler chickens. Use of PrimaLac significantly (P<0.05) enhanced broiler performance by improving body weight and decreasing the feed conversion ratio. Although administration of the probiotic appeared to improve the antibody responses to Newcastle disease virus and infectious bursal disease vaccination, the antibody titres of the probiotic-treated group were not significantly different from those not receiving probiotics.

L-arginine stimulates immune response in chickens immunized with intermediate plus strain of infectious bursal disease vaccine.

Infectious bursal disease continues to pose an important threat to the commercial poultry industry, especially after the emergence of virulent infectious bursal disease virus (IBDV). L-arginine, a ubiquitous, basic amino acid is used as an immunostimulant in variety of human and animal studies with great success in immunosuppressed hosts. In the present study, we evaluated the immunomodulatory effects of L-arginine on humoral and cellular immune response in chickens immunized with live intermediate plus (IP) strain of IBDV vaccine. Chickens vaccinated with IP strain and supplemented with 2% L-arginine showed 100% protection after challenge with virulent IBDV compared to 80% protection induced by IP strain alone. IP strain vaccine elicited good antibody titres in both the groups, IP + L-arginine and IP alone, however, the antibody titres in IP + L-arginine group were significantly higher (P < 0.05) than IP vaccinated chickens. Mitogenic response of peripheral blood lymphocytes to specific IBDV antigen stimulation was significantly higher in IP + L-arginine group (P < 0.05). Peripheral blood lymphocytes were able to rapidly clear the suppressive effects of IP strain and virulent challenge virus in IP + L-arginine group. These results strongly suggest that l-arginine plays a vital role in modulation of protective immune response against IBDV.

Ascorbic acid supplementation improved antibody response to infectious bursal disease vaccination in chickens.

The purpose of the present study was to determine if supplementation of ascorbic acid (AA) to the diet would have a beneficial effect on infectious bursal disease (IBD) vaccination of chickens for protection against infectious bursal disease virus (IBDV) infection. Two hundred forty specific pathogen-free (SPF) chickens were divided into eight experimental groups. A 2 x 2 x 2 factorial arrangement in a completely randomized design was used; AA supplementation at 1,000 ppm in the diet, vaccination, and challenge were the main effects. Prior to challenge and 10 d after challenge, serum AA concentration, serum corticosterone concentration, ELISA antibody titer to IBDV, body weight, bursa-to-body weight (B:B) ratio, and bursal histological score (BHS) were determined. Nonvaccinated chickens fed a diet supplemented with AA did not exhibit clinical signs or mortality following challenge, whereas AA-unsupplemented counterparts had 100% cumulative morbidity and 30% cumulative mortality. Serum AA levels of AA-supplemented and vaccinated chickens were significantly (P < 0.05) higher than AA-unsupplemented and vaccinated chickens. Fourteen days following vaccination, significantly (P < 0.05) higher ELISA titers to IBDV were observed in vaccinated chickens supplemented with AA as compared to AA-unsupplemented counterparts. Ascorbic acid-supplemented chickens, especially those also vaccinated, had higher body weight gains as compared to the AA-unsupplemented chickens. Ascorbic acid-supplemented chickens challenged with IBDV did not show any clinical signs or mortality. The results suggest that supplementation of AA at 1,000 ppm in the diet has beneficial effects on antibody response to IBD vaccination and body weight gain.

Effect of ascorbic acid supplementation on the immune response of chickens vaccinated and challenged with infectious bursal disease virus.

One-day-old chickens were divided into two groups and reared under similar conditions. One group was fed a diet supplemented with 1000ppm ascorbic acid and the other group was fed an identical diet, but not supplemented with ascorbic acid. Both groups were vaccinated against infectious bursal disease (IBD) at 7 days of age and challenged orally with 4x10(5) of 50% embryo-lethal-dose IBDV 14 days later. The number of anti-IBDV antibody secreting cells, production of interleukin-2 (IL-2) by splenocytes, number of CD4(+), CD8(+) and IgM(+) cells in spleen and IgM(+) cells in bursa of Fabricius were compared between the two groups at 7 days (prior to vaccination), 21 days (14 days post-vaccination and prior to challenge) and 31 days (10 days post-challenge) of age. The number of CD8(+) in spleen at 7 days of age and IgM(+) cells in bursa at 7, 21 and 31 days of age were significantly higher in ascorbic acid supplemented group (P<0.05). Production of IL-2 by splenocytes was higher as indicated by higher stimulation indices in ascorbic acid supplemented group. The number of anti-IBDV IgG antibody secreting cells in spleen at 21 and 31 days of age were significantly higher in ascorbic acid supplemented group (P<0.05). Dietary supplementation of ascorbic acid may ameliorate the immunosuppression caused by IBDV vaccination and improve humoral and cellular immune responses.

Immunopotentiating effects of Azadirachta indica (Neem) dry leaves powder in broilers, naturally infected with IBD virus.

Effects of feeding of powdered dry leaves of A. indica (AI) were investigated on humoral and cell mediated immune responses, in a flock of broilers which had survived an outbreak of infectious bursal disease (IBD). AI (2 g/kg) treatment significantly enhanced the antibody titres against new castle disease virus (NCDV) antigen and also potentiated the inflammatory reactions to 1. Chloro-2,4-di- nitro benzene (DNCB) inskin contact test. The results indicate that AI could be beneficial in immunosuppressed condition like IBD, in poultry.

Prevention of infectious bursal disease (IBD) by feeding IBD virus-immune bovine colostrum.

Addition of 5% freeze-dried IBD virus (IBDV)-immune bovine colostrum to the diet of chickens prevented infection when housed in an IBDV-contaminated environment. Four of five chickens receiving 2.5%, and all chickens receiving 0.5% or no IBDV-immune colostrum were infected. No interference with development of an active immunity was found in chickens receiving 5% IBDV-immune colostrum in their diet and vaccinated intramuscularly with modified IBDV.