-
[show abstract]
[hide abstract]
ABSTRACT: Marek's disease (MD) in chickens was first described over a century ago and the causative agent of this disease, Marek's disease virus (MDV), was first identified in the 1960's. There has been extensive and intensive research over the last few decades to elucidate the underlying mechanisms of the interactions between the virus and its host. We have also made considerable progress in terms of developing efficacious vaccines against MD. The advent of chicken genetic map and genome sequence as well as development of approaches for chicken transcriptome and proteome analyses, have greatly facilitated the process of illuminating underlying genetic mechanisms of resistance and susceptibility to disease. However, there are still major gaps in our understanding of MDV pathogenesis and mechanisms of host immunity to the virus and to the neoplastic events caused by this virus. Importantly, vaccines that can disrupt virus transmission in the field are lacking. The current review explores mechanisms of host immunity against Marek's disease and makes an attempt to identify the areas that are lacking in this field.
Developmental and comparative immunology 04/2013; · 3.29 Impact Factor
-
[show abstract]
[hide abstract]
ABSTRACT: Abstract This study examined cytokine gene expression patterns associated with fowl adenovirus (FAdV) infection. The selected cytokine mRNA was quantified by quantitative real-time reverse transcription-PCR in spleen, liver, and cecal tonsil during the course of infection of chickens with a serotype 8 FAdV (FAdV-8). Compared to uninfected chickens, infected birds had higher mRNA expression of interleukin (IL)-18 and IL-10 in spleen and liver, respectively. Interferon gamma (IFN-γ) mRNA expressed in spleen and liver of infected chickens was significantly upregulated, while the expression of IL-8 mRNA in spleen and liver of infected chickens was significantly downregulated. There was no significant difference between infected and uninfected groups in terms of cytokine gene expression in cecal tonsil. These results indicate that these four cytokines might play an important role in driving the immune responses following FAdV-8 infection.
Viral immunology 03/2013; · 1.78 Impact Factor
-
[show abstract]
[hide abstract]
ABSTRACT: Interferon (IFN)-γ is a cytokine with a variety of functions, including direct antiviral activities and the capacity to polarize T-cells. However, there is limited information available about the function of this cytokine in the avian immune system. To gain a better understanding of the biological relevance of IFN-γ in chicken immunity, gain-of-function (upregulation) and loss-of-function (downregulation) studies need to be conducted. RNA interference (RNAi), a technique employed for downregulating gene expression, is mediated by small interfering RNA (siRNA), which can trigger sequence-specific gene silencing. In this regard, sequence specificity and delivery of siRNA molecules remain critical issues, especially to cells of the immune system. Various direct and indirect approaches have been employed to deliver siRNA, including the use of viral vectors. The objectives of the present study were to determine whether RNAi could effectively downregulate expression of chicken IFN-γ in vitro, and investigate the feasibility of recombinant adeno-associated virus to deliver siRNA in vitro as well. Three 27-mer Dicer substrate RNAs were selected based on the chicken IFN-γ coding sequence and transfected into cells or delivered using a recombinant avian adeno-associated virus (rAAAV) into a chicken fibroblast cell line expressing chIFN-γ. The expression of chIFN-γ transcripts was significantly downregulated when a cocktail containing all three siRNAs was used. Expression of endogenous IFN-γ was also significantly downregulated in primary cells after stimulation with a peptide. Further, significant suppression of IFN-γ transcript was also observed in vitro in cells that were treated with rAAAV, expressing siRNA targeting IFN-γ. Off-target effects in the form of triggering IFN responses by RNAi, including expression of chicken 2',5'-oligoadenylate synthetase and IFN-α, were also examined. Our results suggest that siRNAs selected were effective at downregulating IFN-γ in vitro both when delivered directly as well as when expressed by an rAAAV-based vector.
Journal of interferon & cytokine research: the official journal of the International Society for Interferon and Cytokine Research 03/2013; · 1.63 Impact Factor
-
[show abstract]
[hide abstract]
ABSTRACT: Avian erythrocytes are nucleated cells of myeloid origin that are able to actively transcribe and translate proteins. Although their role in gas exchange and transportation has been well described, it has recently been shown that chicken erythrocytes produce cytokines in response to Toll-like receptor (TLR) ligands, which raises the possibility that they also contribute to host immunity. To this end, the objective of the study was to gain some further insight into the immunological role of erythrocytes by identifying the repertoire of TLRs that they express and to elucidate their responses to the TLR3 and TLR21 ligands poly I:C and CpG oligodeoxynucleotide (ODN), respectively. The results suggest that erythrocytes constitutively express transcripts for TLRs 2, 3, 4, 5, and 21, as well as for many immunological genes including type I interferons (IFN) and interleukin (IL)-8. Moreover, it was found that treatment with both poly I:C and CpG ODN up-regulated transcripts for type I IFNs, while only poly I:C up-regulated IL-8 transcripts and enhanced the production of nitrite. Future studies may be aimed at further characterizing the immunological role of erythrocytes.
Research in Veterinary Science 02/2013; · 1.65 Impact Factor
-
[show abstract]
[hide abstract]
ABSTRACT: Campylobacter jejuni is a pathogen of the gastrointestinal tract of humans, but colonizes chickens for prolonged periods without causing disease. It is unclear what host and bacterial mechanisms maintain a non-inflammatory state in chickens. The present work was undertaken to characterize cytokine responses of chickens to purified lipooligosaccharide (LOS) of C. jejuni HS:10. Chickens were injected with purified LOS, and expression of interleukin (IL)-1β (pro-inflammatory cytokine), IL-8 (pro-inflammatory chemokine), interferon (IFN)γ (Th1-like cytokine), IL-10 (immune regulatory/anti-inflammatory cytokine) and IL-13 (Th2-like cytokine) was evaluated in spleen using quantitative RT-PCR, up to 24h post-injection. In an in vitro study, splenocytes were incubated with LOS, and cytokine expression followed up to 18h. Chickens injected with LOS had increased expression of IL-1β up to 24h later. Expression of IL-8 was significantly increased at 2h but then declined below baseline. Expression of IFNγ and IL-10 was increased significantly at 2h, but declined thereafter. Splenocytes incubated with LOS had increased expression of IL-1β and IL-8 up to 18h of incubation. Expression of IFNγ was increased at 6 and 18h, IL-10 was increased at 2h, but expression of IL-13 did not differ significantly up to 18h. It is concluded that LOS of C. jejuni can induce expression of pro-inflammatory IL-1β and IL-8, as well as IFNγ and IL-10 in chickens. More extensive studies with more prolonged exposure to LOS are needed to further clarify the interaction between C. jejuni and the chicken host.
Veterinary Microbiology 02/2013; · 3.33 Impact Factor
-
[show abstract]
[hide abstract]
ABSTRACT: Toll-like receptors (TLRs) are evolutionarily conserved pattern recognition receptors that have been identified in mammals and avian species. Ligands for TLRs are typically conserved structural motifs of microorganisms termed pathogen-associated molecular patterns (PAMPs). Several TLRs have been detected in many cell subsets, such as in macrophages, heterophils and B cells, where they mediate host-responses to pathogens by promoting cellular activation and the production of cytokines. Importantly, TLR ligands help prime a robust adaptive immune response by promoting the maturation of professional antigen presenting cells. These properties make TLR ligands an attractive approach to enhance host-immunity to pathogens by administering them either prophylactically or in the context of a vaccine adjuvant. In this review, we discuss what is known about the immunostimulatory properties of TLR ligands in chickens, both at the cellular level as well as in vivo. Furthermore, we highlight previous successes in exploiting TLR ligands to protect against several pathogens including avian influenza virus, Salmonella, Escherichia coli, and Newcastle disease Virus.
Veterinary Immunology and Immunopathology 12/2012; · 2.08 Impact Factor
-
[show abstract]
[hide abstract]
ABSTRACT: BACKGROUND: Toll-like receptors (TLRs) are evolutionarily conserved pattern recognition receptors that mediate host responses to pathogens. To date, at least 10 different TLRs have been identified in chickens including TLR2, which binds lipopeptides and other similar ligands such as Pam3CSK4, TLR3, which binds double stranded RNA as well as synthetic molecules such as poly I:C, TLR4, which binds lipopolysaccharide (LPS), and TLR21 which binds CpG DNA motifs. In mammals, TLRs have been detected on CD4+ T cells, where they mediate cellular survival, proliferation and the production of cytokines. However, the TLR-mediated responses in chicken CD4+ T cells remain to be determined. As such, the objective of the present study was to elucidate the kinetics of cytokine response to several different TLR ligands in chicken CD4+ T cells. RESULTS: The results suggest that these cells express TLRs 2, 3, 4 and 21 at the transcript level, and treatment with ligands for these TLRs significantly influenced the expression of the cytokines interferon (IFN)-gamma and interleukin (IL)-17, but not IL-4, IL-10 and IL-13. Specifically, treatment with Pam3CSK4, poly I:C and LPS up-regulated IFN-gamma transcripts, while CpG ODN significantly down-regulated them. In contrast, at least one dose of each of the TLR ligands, except for Pam3CSK4, significantly down-regulated IL-17 transcripts. CONCLUSION: Chicken CD4+ T cells respond to ligands for TLRs 2, 3, 4 and 21 by up-regulating or down-regulating cytokine transcripts. Future studies may consider exploring how these TLR ligands may modulate other effector functions in chicken CD4+ T cells, as well as in other T cell subsets such as CD8+ T cells.
BMC Research Notes 11/2012; 5(1):616.
-
[show abstract]
[hide abstract]
ABSTRACT: Toll-like receptors (TLRs) play an important role in the induction of host responses to pathogens. Interactions between TLRs and their ligands result in the production of cytokines that modulate the adaptive immune response through polarizing CD4+ T cells into either T-helper (T(H))1 or T(H)2 phenotypes. In this regard, TLR2 and TLR5 ligands have been shown to induce responses in mammals that are biased toward T(H)1 or T(H)2 phenotypes. However, whether a similar phenomenon occurs in chickens remains to be elucidated. To this end, chicken splenocytes were stimulated with the TLR2 ligand Pam3CSK4 and the TLR5 ligand flagellin, and the relative expression of several cytokines and transcription factors was quantified at 1, 3, 8, and 18 h poststimulation. The results suggest that both TLR ligands induce a mixed T(H)1- and T(H)2-like response, as characterized by the upregulation of both the T(H)1-associated cytokine interferon-γ and the T(H)1-inducing cytokine interleukin (IL)-12, in addition to the T(H)2-associated cytokine IL-4, and in the case of flagellin, IL-13 as well. Future studies may be aimed at assessing the adjuvant potential of these ligands.
Journal of interferon & cytokine research: the official journal of the International Society for Interferon and Cytokine Research 10/2012; · 1.63 Impact Factor
-
Payvand Parvizi,
Amirul Islam Mallick,
Kamran Haq,
Hamid R Haghighi,
Shahriar Orouji,
Niroshan Thanthrige-Don,
Michael St Paul,
Jennifer T Brisbin,
Leah R Read,
Shahriar Behboudi, Shayan Sharif
[show abstract]
[hide abstract]
ABSTRACT: Abstract Marek's disease (MD) is caused by Marek's disease virus (MDV). Various vaccines including herpesvirus of turkeys (HVT) have been used to control this disease. However, HVT is not able to completely protect against very virulent strains of MDV. The objective of this study was to determine whether a vaccination protocol consisting of HVT and a Toll-like receptor (TLR) ligand could enhance protective efficacy of vaccination against MD. Hence, chickens were immunized with HVT and subsequently treated with synthetic double-stranded RNA polyriboinosinic polyribocytidylic [poly(I:C)], a TLR3 ligand, before or after being infected with a very virulent strain of MDV. Among the groups that were HVT-vaccinated and challenged with MDV, the lowest incidence of tumors was observed in the group that received poly(I:C) before and after MDV infection. Moreover, the groups that received a single poly(I:C) treatment either before or after MDV infection were better protected against MD tumors compared to the group that only received HVT. No association was observed between viral load, as determined by MDV genome copy number, and the reduction in tumor formation. Overall, the results presented here indicate that poly(I:C) treatment, especially when it is administered prior to and after HVT vaccination, enhances the efficacy of HVT vaccine and improves protection against MDV.
Viral immunology 08/2012; 25(5):394-401. · 1.78 Impact Factor
-
[show abstract]
[hide abstract]
ABSTRACT: Toll-like receptors (TLRs) are an evolutionarily conserved group of pattern recognition receptors that play an important role in mediating host-responses to pathogens. Several TLRs have been identified in chickens and their expression has been detected in many immune cell subsets including in B cells. However, the mechanisms through which TLRs modulate B cell responses have not been well characterized in chickens. The aim of the present study was to elucidate the responses mounted by cells of the bursa of Fabricius to treatment with the TLR 3, 4 and 21 ligands, poly I:C, lipopolysaccharide (LPS) and CpG oligodeoxynucleotides (ODN), respectively. The relative expression of several immune system genes was quantified at 1, 3, 8 and 18h post-treatment. The results show that all three ligands induced the up-regulation of interferon (IFN)-γ and interleukin (IL)-10 transcripts and promoted the up-regulation of transcripts associated with antigen presentation, namely CD80 and major histocompatibility complex (MHC) class II. Furthermore, the results indicated that LPS and poly I:C induced the greatest IFN-γ and IL-10 responses, respectively, while CpG ODN was the most efficacious inducer of CD80 and MHC-II expression. Future studies may be aimed at elucidating the mechanisms of TLR-mediated activation of chicken B cells. These mechanisms may be then exploited for the development of adjuvants with enhanced ability to stimulate B cell responses.
Veterinary Immunology and Immunopathology 07/2012; 149(3-4):237-44. · 2.08 Impact Factor
-
[show abstract]
[hide abstract]
ABSTRACT: Invariant NKT (iNKT) cells are glycolipid-reactive lymphocytes with anti-microbial properties. Toll-like receptor (TLR)-primed antigen-presenting cells are known to activate iNKT cells, however, the expression and function of TLRs in iNKT cells remain largely unknown. Here, we show that TCR-activation of murine iNKT cells by α-GalactosylCeramide (α-GalCer) or anti-CD3 antibodies can result in increased expression of TLR genes. TLR3, 5 and 9-mediated costimulation of TCR-preactivated iNKT cells resulted in enhancement of iNKT cell activation, as determined by their cytokine production. Expression of TLR3 and 9 at protein level was also confirmed in TCR-activated iNKT cells. Furthermore, TCR-preactivation followed by TLR9-costimulation of iNKT cells increased their ability to induce maturation of dendritic cells. Thus, our findings show that iNKT cells can up-regulate their TLR expression upon TCR activation and a subsequent TLR-signaling in these cells can lead to their enhanced activation, suggesting a new possible mode of iNKT cell activation.
Cellular Immunology 06/2012; 277(1-2):33-43. · 1.97 Impact Factor
-
Payvand. Parvizi,
A. I. Mallick,
Kamran Haq,
Hamid Haghighi,
Shahriar Oruji,
Niroshan Thanthrige-Don,
Michael St Paul,
Jennifer Brisbin,
Leah Read,
Shahriar,
Behboudi, Shayan Sharif
Viral Immunology 05/2012; · 1.97 Impact Factor
-
[show abstract]
[hide abstract]
ABSTRACT: Avian influenza viruses (AIV) pose a threat towards the health of both poultry and humans. To interrupt the transmission of the virus, novel prophylactic strategies must be considered which may reduce the shedding of AIV. One potential is the prophylactic use of Toll-like receptor (TLR) ligands. Many cells of the immune system express TLRs, and cellular responses to TLR stimulation include activation and the production of cytokines. TLR ligands have been employed as prophylactic treatments to enhance host resistance to pathogens both in mammals and chickens. Therefore, the present study was conducted to determine whether TLR ligands may be used prophylactically in chickens to enhance host immunity to AIV. Chickens received intramuscular injections of either low or high doses of the TLR ligands poly I:C, lipopolysaccharide (LPS) and CpG ODN. Twenty-four hours post-treatment, chickens were infected with the low pathogenic avian influenza virus H4N6, and both oropharyngeal and cloacal virus shedding were assessed on days 4 and 7 post-infection. To identify potential correlates of immunity, spleen and lungs were collected on days 2, 4 and 7 post-infection for RNA extraction. The results suggested that all of the TLR ligand treatments induced a significant reduction in virus shedding, with the TLR3 ligand poly I:C conferring the greatest AIV immunity compared to control birds, followed by CpG ODN and LPS. Furthermore, transcriptional analysis of gene expression in the spleen and lungs suggest IFN-α and IL-8 as correlates of immunity conferred by poly I:C, and IFN-γ for CpG ODN and LPS. In conclusion, TLR ligands, have the ability to enhance host immunity against AIV, and future studies should consider exploring the combinatory effects of poly I:C and CpG ODN prophylaxis in conjunction with AIV vaccination.
Vaccine 04/2012; 30(30):4524-31. · 3.77 Impact Factor
-
[show abstract]
[hide abstract]
ABSTRACT: The use of virosomes as a vaccine platform has proven successful against several viruses. Here we examined the protective efficacy of a virosome-based vaccine consisting of avian influenza virus (AIV) A/Duck/Czech/56/H4N6 in chickens against a homologous AIV challenge. Virosomes adjuvanted with CpG-ODN or recombinant chicken interferon (IFN)-γ significantly reduced virus shedding after virus challenge. Furthermore, immunization with virosomes adjuvanted with CpG-ODN increased hemagglutination inhibition (HI) and virus-specific neutralizing serum antibodies, as well as virus-specific serum IgG and mucosal IgA responses. We also found a significant increase in the expression of type I and II interferon genes in the protected birds following virus challenge. In summary, this study demonstrated the ability of virosomes adjuvanted with CpG-ODN to reduce AIV shedding, and elicit virus-specific protective antibody responses in vaccinated birds.
Viral immunology 04/2012; 25(3):226-31. · 1.78 Impact Factor
-
Vaccine 04/2012; · 3.77 Impact Factor
-
Viral Immunology 03/2012; · 1.97 Impact Factor
-
Vaccine. 03/2012;
-
[show abstract]
[hide abstract]
ABSTRACT: Several highly efficacious vaccines are currently available for control of Marek's disease, a lymphoproliferative disease in chickens. However, these vaccines are unable to prevent infection with Marek's disease virus (MDV) in vaccinated birds. This leads to shedding of virulent MDV from feather follicle epithelium and skin epithelial cells of vaccinated and infected chickens. The objective of the present study was to study the interactions between a vaccine strain (CVI988/Rispens) and a very virulent strain of MDV (RB1B) in feathers. We examined genome load and replication of CVI988 and MDV-RB1B strains at various time points post infection. Moreover, we evaluated cytokine expression in feathers as indicators of immunity generated in response to vaccines against MDV. Analysis of feathers collected between 4 and 21 days post infection (d.p.i.) revealed a steady level of CVI988 genome load in the presence or absence of RB1B. Infection with MDV resulted in a significant increase in RB1B genome load peaking at 14 d.p.i. Importantly, vaccination with CVI988 resulted in a significant reduction in accumulation of MDV-RB1B in feathers. RB1B genome accumulation in feather tips was associated with increased expression of interferon-α at 14 d.p.i. and interferon-Sγ at earlier time points, 4 and 7 d.p.i. compared with 10 and 14 d.p.i. Interleukin-10 and interleukin-6 were up-regulated at 14 d.p.i. in the infected groups. This study expands our understanding of the dynamics of replication of vaccine and virulent MDV strains in the feathers and illuminates mechanisms associated with immunity to Marek's disease.
Avian Pathology 02/2012; 41(1):69-75. · 1.71 Impact Factor
-
[show abstract]
[hide abstract]
ABSTRACT: Thrombocytes are the avian equivalent to mammalian platelets. In addition to their hemostatic effects, mammalian platelets rely in part on pattern recognition receptors, such as the Toll-like receptors (TLR), to detect the presence of pathogens and signal the release of certain cytokines. Ligands for TLRs include lipopolysaccharide (LPS), which is bound by TLR4, as well as unmethylated CpG DNA motifs, which are bound by TLR9 in mammals and TLR21 in chickens. Similar to mammalian platelets, avian thrombocytes have been shown to express TLR4 and secrete some pro-inflammatory cytokines in response to LPS treatment. However, the full extent of the contributions made by thrombocytes to host immunity has yet to be elucidated. Importantly, the mechanisms by which TLR stimulation may modulate thrombocyte effector functions have not been well characterized. As such, the objective of the present study was to gain further insight into the immunological role of thrombocytes by analyzing their responses to treatment with ligands for TLR4 and TLR21. To this end, we quantified the relative expression of several immune system genes at 1, 3, 8 and 18 hours post-treatment using real-time RT-PCR. Furthermore, production of nitric oxide and phagocytic activity of thrombocytes was measured after their activation with TLR ligands. We found that thrombocytes constitutively express transcripts for both pro- and anti-inflammatory cytokines, in addition to those associated with anti-viral responses and antigen presentation. Moreover, we found that both LPS and CpG oligodeoxynucleotides (ODN) induced robust pro-inflammatory responses in thrombocytes, as characterized by more than 100 fold increase in interleukin (IL)-1β, IL-6 and IL-8 transcripts, while only LPS enhanced nitric oxide production and phagocytic capabilities. Future studies may be aimed at examining the responses of thrombocytes to other TLR ligands.
PLoS ONE 01/2012; 7(8):e43381. · 4.09 Impact Factor
-
[show abstract]
[hide abstract]
ABSTRACT: Toll-like receptors (TLRs) are a group of conserved proteins that play an important role in pathogen recognition in addition to the initiation and regulation of innate and adaptive immune responses. To date, several TLRs have been identified in chickens, each recognizing different ligands. TLR stimulation in chickens has been shown to play a role in host-responses to pathogens. However, the mechanisms through which TLRs modulate the chicken immune system have not been well examined. The present study was conducted to characterize the kinetics of responses to TLR4 and TLR21 stimulation in chickens following intramuscular injections of their corresponding ligands, lipopolysaccharide (LPS) and CpG oligodeoxynucleotides (ODNs), respectively. To this end, relative expression of cytokine genes in the spleen was determined at 2, 6, 12 and 24 h after injection of TLR ligands. The results indicated that LPS strongly induced the up-regulation of some immune system genes early on in the response to treatment, including interferon (IFN)-γ, interleukin (IL)-10, and IL-1β. Furthermore, treatment with CpG ODN promoted the up-regulation of major histocompatibility complex (MHC)-II, IFN-γ and IL-10. The response to CpG ODN appeared to be somewhat delayed compared to the response to LPS. Moreover, we found a significant increase in IFN-α gene expression in response to LPS but not CpG ODNs. Future studies may be aimed to further characterize the molecular mechanisms of TLR activation in chickens or to exploit TLR agonists as vaccine adjuvants.
Veterinary Immunology and Immunopathology 12/2011; 144(3-4):228-37. · 2.08 Impact Factor
