Effects of IBDV infection on expression of chTLRs in chicken bursa

Expression of Toll-like receptors and host defence peptides in the cecum of chicken challenged with Eimeria tenella

Chicken coccidiosis, caused by Eimeria protozoa, affects poultry farming. Toll-like receptors (TLRs) and host defence peptides (HDPs) help host innate immune responses to eliminate invading pathogens, but their roles in Eimeria tenella infection remain poorly understood. Herein, 14-day-old chickens were treated orally with 50,000 E. tenella oocysts and the cecum was dissected at different timepoints. mRNA expression of 10 chicken TLRs (chTLRs) and five HDPs was measured by quantitative real-time PCR. chTLR7 and chTLR15 were upregulated significantly at 3 h post-infection while other chTLRs were downregulated (p < .05). chTLR1a, chTLR1b, chTLR2b and chTLR4 peaked at 36 h post-infection, chTLR3, chTLR5 and chTLR15 peaked at 72 h post-infection and chTLR21 expression was highest among chTLRs, peaking at 48 h post-infection (p < 0.05). For HDPs, cathelicidin (CATH) 1 to 3 and B1 peaked at 48 h post-infection, liver-expressed antimicrobial peptide 2 peaked at 96 h post-infection, and CATH 2 expression was highest among HDPs. CATH2 and CATH3 were markedly upregulated at 3 h post-infection (p < .05). The results provide insight into innate immune molecules during E. tenella infection in chicken, and indicate that innate immune responses may mediate resistance to chicken coccidiosis.

Effect of Bacillus subtilis Supplemented Diet on Broiler's Intestinal Microbiota and TLRs Gene Expression

This study aimed to investigate the effects of dietary Bacillus subtilis supplementation on gut microbiota diversity, digestive enzyme activity, and Toll-like receptor (TLR) expression in broiler chickens. A total of 240 "817" crossbred broiler chickens were randomly assigned to four groups: control (basal diet, BD), group I (BD + 300 g/d B. subtilis at 1.08 × 107 CFU/kg), group II (BD + 600 g/d B. subtilis at 2.16 × 107 CFU/kg), and group III (BD + 900 g/d B. subtilis at 3.24 × 107 CFU/kg). Gut microbiota analysis revealed significant improvements in the abundance of specific microorganisms in the treatment groups, with distinct variations in the core microorganisms between the groups. Notably, protease activity in the ileum was significantly increased in groups II (22.59%; p < 0.01) and III (14.49%; p < 0.05) compared to that in the control group. Moreover, significant up-regulation of TLR1A and TLR7 expression was observed in jejunum and cecum of the treated groups. Additionally, the TLR1B expression in the ileum was significantly increased. Furthermore, TLR2A and MyD88 transcription levels were significantly elevated in the jejunum, liver, spleen, and kidneys of experimental groups. Modulations in the expression of various TLR's (TLR2B, TLR3, TLR4, TLR15, and TLR21) were also observed in different organs. The spleen and kidney of B. subtilis-supplemented chickens exhibited upregulated expression of the proinflammatory cytokine IL-1β. Dietary supplementation with B. subtilis in broiler chickens improved the gut microbiota diversity and significantly upregulated TLR's expression in various organs. B. subtilis could be a valuable feed additive, contributing to improved disease management and overall health in broiler chickens.

Effects of Salmonella Enteritidis infection on TLRs gene expression and microbial diversity in cecum of laying hens

Salmonella Enteritidis (SE) is an important foodborne pathogen primarily causing human disease through contaminated food and water. In the current study, to assess the effect of Salmonella Enteritidis infection on the immune system and the microbial diversity of cecum and oviduct in chickens, twelve 24-week-old SE-negative White Leghorn layers were randomly selected and divided into 2 groups. Chickens in the challenge group were orally inoculated with SE, and chickens in the control group received an equal amount of sterilized Phosphate Buffered Saline solution. Serum and tissue samples (cecum, oviduct, ovary, liver, spleen, and pancreas) were collected at 7 days and 14 days post-infection (dpi). Quantitative PCR was used to detect the expression of Toll-like receptors (TLRs) in the cecum, oviduct and ovary. To understand the influence of SE infection on the microbial profile of the cecum and oviduct, microbial community composition of the cecal contents and oviducal contents were analyzed through 16S rRNA sequencing. Results showed that SE infection caused damage to the digestive organs, reproductive organs, and immune organs in laying hens. The expression of TLR1a, TLR1b, TLR2, TLR4, TLR5, TLR7 and TLR15 in the cecum were induced, and the content of IFN-γ, TNF-α, IL-2 and IL-18 in serum increased after SE infection. The composition of the microbial community significantly changed in cecal content, the dominant phylum of Firmicutes increased, and Bacteroidetes decreased significantly. In the oviduct, the microbial diversity became complicated, the dominant bacteria Faecalibacterium was significantly increased, and Bacteroides was significantly decreased. This study investigated the effects of SE infection in laying hens, including host innate immunity, the expression of TLRs, and changes in the composition of microbes in the cecum and reproductive tract. Our results may provide a scientific basis for the Salmonella Enteritidis control in chicken, the maintenance of oviduct function, and the guarantee of clean egg production.

Infectious bursal disease virus' interferences with host immune cells: What do we know?

AbstractInfectious bursal disease virus (IBDV) induces one of the most important immunosuppressive diseases in chickens leading to high economic losses due increased mortality and condemnation rates, secondary infections and the need for antibiotic treatment. Over 400 publications have been listed in PubMed.gov in the last five years pointing out the research interest in this disease and the development of improved preventive measures. While B cells are the main target cells of the virus, also other immune and non-immune cell populations are affected leading a multifaceted impact on the normally well orchestrated immune system in IBDV-infected birds. Recent studies clearly revealed the contribution of innate immune cells as well as T cells to a cytokine storm and subsequent death of affected birds in the acute phase of the disease. Transcriptomics identified differential regulation of immune related genes between different chicken genotypes as well as virus strains, which may be associated with a variable disease outcome. The recent availability of primary B cell culture systems allowed a closer look into virus-host interactions during IBDV-infection. The new emerging field of research with transgenic chickens will open up new opportunities to understand the impact of IBDV on the host also under in vivo conditions, which will help to understand the complex virus-host interactions further.

Melanocytes in black-boned chicken have immune contribution under infectious bursal disease virus infection

In black-boned chicken, melanocytes are widely distributed in their inner organs. However, the roles of these cells are not fully elucidated. In this study, we used 3-wk-old female Silky Fowl to investigate the functions of melanocytes under infection with infectious bursal disease virus (IBDV). We found the melanocytes in the bursa of Fabricius involved in IBDV infection shown as abundant melanin were transported into the nodule and lamina propria where obvious apoptotic cells and higher expression of BAX were detected. Genes related to the toll-like receptor (TLR) signaling pathway were highly detected by quantitative PCR, including TLR1, TLR3, TLR4, TLR15, myeloid differential protein-88, interferon-α, and interferon-β. We then isolated and infected primary melanocytes with IBDV in vitro and found that higher expressions of immune genes were detected at 24 and 48 h after infection; the upregulated innate and adaptive immune genes were involved in the pathogenesis of IBDV infection, including TLR3, TLR7, interleukin 15 (IL15), IL18, IL1rap, CD7, BG2, ERAP1, and SLA2. These changes in gene expression were highly associated with microtubule-based movement, antigen processing and presentation, defense against viruses, and innate immune responses. Our results indicated that the widely distributed melanocytes in Silky Fowl could migrate to play important innate immune roles during virus infection.

Effects of infectious bursal disease virus infection on interferon and antiviral gene expression in layer chicken bursa

Layer chickens were artificially challenged with infectious bursal disease virus (IBDV), and the kinetics of IFN-λ and antiviral genes in the bursa were explored using quantitative real-time PCR. Data showed that after the chickens were infected with IBDV, the virus load in the bursa of the Fabricius peaked at 96 h and gradually decreased. The relative mRNA expression levels of IFN-λ and antiviral genes (zinc-finger antiviral protein [ZAP], interferon alpha-inducible protein 6 [IFI6], laboratory of genetics and physiology 2 [LGP2], virus inhibitory protein [Viperin], and Mx) of the infected group dramatically increased at 24-168 h compared with those of the negative-infected group. Furthermore, the ZAP mRNA expression peaked at 24 h (3.97-fold). The Viperin mRNA transcript level was highest at 48 h (384.60-fold). The mRNA expression levels of IFI6 (96.31-fold), LGP2 (18.29-fold), and Mx (88.85-fold) peaked at 72 h, and that of IFN-λ was most remarkable at 96 h (2978.81-fold). Furthermore, the ZAP change rule was significantly positively correlated with the change rule of the IBDV load. The mRNA expression levels of IFN-λ and antiviral genes (ZAP, IFI6, LGP2, Viperin, and Mx) increased as the virus expression increased and then decreased. These results further corroborated that the IBDV infection seriously interfered with the chicken's innate immune response.