Infectious Bursal Disease Virus-infected Chickens Research Articles

The effect of ghrelin on the fibrosis of chicken bursa of fabricius infected with infectious bursal disease virus

The present study aimed to investigate the effect of ghrelin on the degree of bursa of Fabricius (BF) fibrosis in infectious bursal disease virus-infected chickens. Specific pathogen free (SPF) chicks were divided into four groups. One group was used as the control (“C”). The other three groups were inoculated with IBDV on the 19th day, of which two were injected intraperitoneally with 0.5 nmol (“LG”) or 1.0 nmol (“HG”) ghrelin/100 g weight from the 18th day to the 22nd day, and one was injected intraperitoneally with PBS (“I”). Hematoxylin-eosin staining, Masson's staining, and quantitative real-time PCR were used to determine the effects of ghrelin on the degree of inflammatory cell infiltration, the bursal fibrosis degree, and the expression of TGF-β and MMP-9 mRNA in IBDV-infected SPF chicks. The results showed that ghrelin administration reduced the number of infiltrated inflammatory cells in BF from 5 dpi and significantly attenuated the degree of fibrosis induced by IBDV from 2 dpi to 7 dpi (P < 0.05). Moreover, the TGF-β expression in the LG and HG groups were significantly or highly significantly lower (P < 0.05 or P < 0.01) than those of I group from 2 dpi to 5 dpi. In addition, ghrelin administration downregulated MMP-9 expression evoked by IBDV from 2 dpi to 7 dpi (P < 0.05 or P < 0.01). These results suggested that ghrelin attenuated the bursal fibrosis degree of IBDV-infected SPF chicks by reducing the number of inflammatory cells and by decreasing the expression of TGF-β and MMP-9, which shortened the process of bursa recovery.

English

Infectious Bursal Disease (IBD) is an economically important irreversible immunosuppressive disease of young birds. The present study was designed to confirm the efficacy of two common diagnostic tests for the detection of Infectious Bursal Disease Virus (IBDV) from the three types of bursal samples collected from a recent outbreak in layer and broiler chickens of Gazipur district, Bangladesh. This study compared the degree of sensitivity between Ouchterlony Double Immunodiffusion Test (ODIT) and Reverse Transcription Polymerase Chain Reaction (RT-PCR) for the detection of IBD viral antigen from the bursal samples. A total of 180 field bursal samples (80 broiler and 100 from layer chicken) from suspected IBDV infected dead chickens were collected from 50 different poultry farms. Bursal homogenates were used to detect IBDV using ODIT and RT-PCR. Three types of bursal samples, hemorrhagic bursa (90), edematous bursa (78) and atrophied bursa (12) were selected for the detection of viral antigen. A panel of anti-sera and IBDV specific primer for VP2 gene was used for RT-PCR. The data demonstrated that, out of 180 field samples, 164 (91%) were positive by RT-PCR and 120 (67%) were positive by ODIT. Haemorrhagic bursas were more sensitive compared to oedematous bursas while no virus was detected from the samples of atrophied bursa. This study demonstrated that, RT-PCR was more sensitive and effective diagnostic tool compared to that of ODIT. Key words: Infectious bursal disease virus (IBDV), ouchterlony double immunodiffusion test (ODIT), reverse transcription polymerase chain reaction (RT-PCR), bursa, broiler, layer.

Phylogeny and evolution of infectious bursal disease virus circulating in Turkish broiler flocks

ABSTRACTThe emergence of new infectious bursal disease virus (IBDV) variants can threaten poultry health and production all over the world causing significant economic losses. Therefore, this study was performed to determine IBDV molecular epidemilogy, VP2 gene variation, and corresponding pathological lesions in IBDV infected chickens in Turkey. For this, 1855 bursa of Fabricius samples were collected from 371 vaccinated broiler flocks. Atrophia and haemorrhages were seen in the bursa Fabricius of very virulent IBDV (vvIBDV) infected chickens. Partial VP2 gene was sequenced and phylogenetic, recombination, and evolutionary analyses were performed. 1548 (83.5%) out of 1855 of bursa of Fabricius samples were IBDV positive and 1525 of those could be sequenced. The recombination analysis did not detect occurrence of any recombination event among the Turkish strains. Among 1525 sequenced samples, 1380 of them were found to be classical strains. Among 1380 classical strains, 1317 were similar to IBDV 2512, 11 to Faragher 52/70, 40 to 228 E, and 12 to Lukert strain. Out of 1525 reverse transcriptase ploymerase chain reaction positive samples, 144 of them were found to be similar to vvIBDV-VP2 gene reported to GenBank previously. The phylogenetic tree performed on a broad sequence dataset demonstrated grouping of vvIBDV Turkish strains in three different clusters, including sequences collected also from Iraq and Kuwait (Cluster 1), Indian (Cluster 2), and a distinct Turkish-only cluster (Cluster 3). The evolutionary rate estimation on branches/clades including Turkish strain mirrored the expected one for RNA viruses and no significant differences were found among different considered branches. In conclusion, results of this study indicate that vvIBDV strains similar to those circulating in various countries in the Middle East are present and undergoing evolution in chickens from Turkish broiler flocks. This point needs to be taken into account in planning adequate control strategies.

Effect of infectious bursal disease virus on pathogenicity of avian influenza virus subtype H9N2 in broiler chicks

In this experiment, pathogenesis of H9N2 avian influenza virus (AIV), experimentally infected with infectious bursal disease virus (IBDV) in broiler chicks was examined. Three groups of twenty were randomly selected. Day old chickens in group 1, were infected by 103 CID50 of IBDV intrabursaly, and in thirty days of age groups 1 and 2 were challenged with 106 EID50 H9N2, intranasaly-intraoculary. Chickens in group 3 remained as control (uninfected with neither IBDV or AIV). Tracheal and cloacal swabs, and tissue samples, were collected at 3, 7, and 11 days postinoculation (PI). Serum samples examined for antibodies against avian influenza virus (AIV) by hemagglutination inhibition test (HI). IBD caused lower H9N2 antibody level. IBDV infected chickens (g1) shed AI virus for a longer period than AIV infected birds (g2), from both trachea and cloac. IBDV was related with AIV in brain and liver. Isolation of AIV from trachea, conjunctiva, bursa and lung in IBDV infected group (1), prolonged till 11 days PI. Our study provides evidence that a previous history of IBDV infection in chickens may cause them to be more susceptible to H9N2 low pathogenic avian influenza (LPAI) virus infection and may alter its tissue tropism. Key words: Infectious bursal disease, avian influenza, virus shedding, broiler chicks.

Changes in the Cytokine and Toll-Like Receptor Gene Expression Following Infection of Indigenous and Commercial Chickens With Infectious bursal disease virus

A comparative study of cytokine and toll-like receptor (TLR) mRNA expression in 3weeks old indigenous and commercial chickens infected with a very virulent strain of Infectious bursal disease virus (IBDV) was performed using a custom-made microarray chip. In uninfected indigenous chickens, the basal levels of interleukin (IL) 15 were lower and IL 16 was higher than their commercial counterparts. In the IBDV infected indigenous chickens, only IL16 gene expression was down regulated, while TLR3 expression was up regulated significantly. In the IBDV infected commercial chickens IL15, IL16 and TLR3 were down regulated. But, IL1-β, IL2, IL8, IL12, IL17, interferon (IFN)-α and β were significantly increased compared with the control. In IBDV infected indigenous chickens, IL15, IFN-γ, beta-defensin and TLR3 were up regulated compared to virus-infected commercial chickens. The results suggested that up regulation of TLR3, a ligand for double-stranded (ds) RNA probably could account for the possible clinical resistance in these birds. There was a 5.2 fold difference by quantitative real-time RT-PCR between indigenous and commercial chickens in TLR3 mRNA expression. Therefore, TLR3, a receptor for dsRNA could be a putative molecule that could play a role in differential innate and adaptive immune responses to IBDV in commercial and indigenous chickens.

Nutrition and immunity: the effects of the combination of arginine and tryptophan on growth performance, serum parameters and immune response in broiler chickens challenged with infectious bursal disease vaccine

To explore the effects of the combination of tryptophan (Trp) and arginine (Arg) on growth performance, serum parameters and immune response of broiler chickens challenged with intermediate plus strain of infectious bursal disease virus vaccine, an in vivo experiment was conducted. A corn–soybean meal-based diet containing different levels of Arg and Trp was used. Cobb500 male broiler chickens from 0 to 49 days of age were subjected to a diet supplemented with the combination of Trp and Arg. Growth performance parameters and serum parameters were measured at 27 and 49 days of age. To evaluate the immunomodulatory effects of the combination of Trp and Arg on the challenged chickens, we measured the serum levels of interferon-α, interferon-γ and immunoglobulin G at 27, 35, 42, and 49 days of age. The results showed that the three evaluated immune system parameters including interferon-α, interferon-γ and immunoglobulin G were significantly enhanced after treatment. This enhancement resulted in the recovery of infectious bursal disease virus-infected chickens compared with controls as confirmed by histopathological examinations. Moreover, serum parameters such as albumin and total protein increased, whereas the treatment decreased (P<0.05) the feed:gain ratio, aspartate amino-transferase, alkaline phosphatase, lactic dehydrogenase, triglyceride and cholesterol. These findings suggest that the combination of Arg and Trp has a regulatory effect on growth performance. Moreover, it modulates the systemic immune response against infectious bursal disease.

Expression of perforin–granzyme pathway genes in the bursa of infectious bursal disease virus-infected chickens

Infectious bursal disease (IBD) is an economically important immunosuppressive disease of chickens. The IBD virus (IBDV) actively replicates in B cells and causes severe bursal damage. Generally, T cells are refractory to infection with IBDV but are known to promote virus clearance. However, the mechanisms of T cell mediated viral clearance are not well understood. In this study, we evaluated the molecular mechanisms of cytotoxic T cell responses in the pathogenesis of IBD in chickens. Infection of chickens with IBDV was accompanied by the infiltration of CD4 + and CD8 + T cells in the bursa. There was an upregulation in the gene expression of important cytolytic molecules; perforin (PFN), granzyme-A (Gzm-A), DNA repair and apoptotic proteins; high mobility proteins group (HMG) and poly (ADP-ribose) polymerase (PARP) in the bursa of Fabricius (BF) whereas expression of NK (natural killer) lysin was downregulated. Importantly, PFN producing CD4 + and CD8 + T cells were also detected in the bursa of IBDV-infected chickens by immunohistochemistry. The Th1 cytokines, IL-2 and IFN-γ expression was also strongly upregulated, suggesting the activation of T cells. The findings of this study highlight the mechanisms of IBD pathogenesis and the role of cytotoxic T cells in the clearance of virus-infected cells.

Detection of Antibodies to Infectious Bursal Disease Virus (IBDV) by Agar Gel Immunodiffusion using Recombinant VP2 Protein

Infectious bursal disease virus (IBDV) causes a highly contagious and immunosuppressive disease of chicken. Agar gel immunodiffusion using IBDV antigen extracted from bursa of Fabricius of infected chicken has been used officially for diagnosis of IBDV in Korea. In this study, in order to replace the IBDV whole virus antigen with non-infectious antigen, recombinant VP2 protein (rVP2) of IBDV was produced using recombinant baculovirus expression system. Purified baculovirus-expressed rVP2 was used as an antigen in an agar gel immunodiffusion (AGID). rVP2 antigen precipitated specifically IBDV antibodies. AGID using rVP2 antigen detected anti-IBDV antibodies from 6 dpi to 28 dpi (termination of the experiment) when specific pathogen free chickens were experimentally infected with IBDV 52/70 strain. This was consistent with result by AGID using IBDV antigen, virus neutralization test (VNT) and a commercial ELISA kit (except for one serum). The sensitivity of rVP2 was the same with that of IBDV antigen when field sera (n=324) were tested by AGID. However, AGID using rVP2 antigen detected maternal antibodies from broiler chickens (n=20) on a broiler farm up to 15 days old, although the detection rate of the AGID was relatively low compared to a commercial ELISA kit. Our results indicate that IBDV whole virus antigen from IBDV infected chickens would be replaced with recombinant VP2 protein as an antigen for AGID.

Humoral and cell-mediated immune responses in chickens with infectious bursal disease

Primary and secondary immune responses to Newcastle disease virus (NDV) was evaluated in chickens infected with infectious bursal disease virus (IBDV) at one and 28 days of age. The geometric mean primary hemagglutination-inhibition antibody titers (GMT) of chickens infected with IBDV at one day of age was significantly lower ( P ⩽ 0.01) than those infected at 28 days of age. Infection with IBDV had no influence on secondary immune response to NDV. The effect of IBDV infection at one day of age on the cell-mediated immunity of chickens was evaluated by skin allograft acceptance or survival time. There was no significant difference between the percentage of grafts accepted in IBDV infected and noninfected control chickens. However, the mean graft survival time in the IBDV infected chickens was significantly longer ( P ⩽ 0.05) than those in the control group. This suggested a suppression of cell-mediated immunity due to IBDV infection.

Sequential Changes in the Number of Surface Immunoglobulin-Bearing B Lymphocytes in Infectious Bursal Disease Virus-Infected Chickens

Variations of B lymphocytes bearing surface immunoglobulin (SIg) M [SIg(M)] and G [SIg(G)] were studied in the spleen and peripheral blood of chickens infected with infectious bursal disease virus (IBDV). The proportion of SIg-bearing B lymphocytes and SIg(M)- and SIg(G)-bearing B cells in chickens infected at one day of age decreased from 1 week postinfection (p.i.) onward and was significantly lower at 8 weeks p.i. In chickens infected at 4 weeks, the percentage of SIg-bearing B cells decreased severely during the first 2 weeks p.i. The decrease of SIg(M)-bearing B cells preceded that of SIg (G)-bearing B cells: the lowest percentage of SIg(M)-bearing B cells has observed 2 to 3 days p.i., and that of SIg(G)-bearing B cells was seen 4 days p.i. The results suggest that SIg(M)-bearing B cells are the major target for IBDV infection.