Search Results (35)

Research on the immunological development of lymphoid organs in chicks has been extensive, yet a significant gap exists in our understanding of innate immunity during embryonic life within the intestinal tract. This study investigated the developmental trajectory of intestinal immunity in chick embryos by evaluating basal gene expression levels of key immune markers at embryonic days (ED) 14, 17, and 20. The results indicated variable expression levels of cytokines, antimicrobial peptides (AMPs), and Toll-like receptor (TLRs) genes throughout the intestinal tract. Most cytokines and chemokines exhibited elevated expression in the cecum, while AMPs, including avian-β-defensins (AvBDs) and cathelicidins (CATHs) genes, showed increased levels in the jejunum at ED20. The findings from the developmental trajectory analysis of these genes revealed elevated expression levels of cytokines, including interferon (IFN)-γ, interleukin (IL)-6, IL-13, and transforming-growth factor (TGF)-β in the cecum at ED20. However, no consistent patterns were observed for AvBDs, CATHs, and TLRs, as their expression varied across different developmental stages of the chick embryo. These findings significantly contribute to our understanding of intestinal immune system development in chick embryos and provide a foundation for further research aimed at enhancing immune capabilities, especially in segments with lower expression levels of immunomodulatory genes. Full article

Immunoglobulin Y (IgY) is the primary antibody found in the eggs of chicken (Gallus domesticus), allowing for large-scale antibody production with high titers, making them cost-effective antibody producers. IgY serves as a valuable alternative to mammalian antibodies typically used in immunodiagnostics and immunotherapy. Compared to mammalian antibodies, IgY offers several biochemical advantages, and its straightforward purification from egg yolk eliminates the need for invasive procedures like blood collection, reducing stress in animals. Due to the evolutionary differences between birds and mammals, chicken antibodies can bind to a broader range of epitopes on mammalian proteins than their mammalian counterparts. Studies have shown that chicken antibodies bind 3–5 times more effectively to rabbit IgG than swine antibodies, enhancing the signal in immunological assays. Additionally, IgY does not interact with rheumatoid factors or human anti-mouse IgG antibodies (HAMA), helping to minimize interference from these factors. IgY obtained from egg yolk of hens immunized against Pseudomonas aeruginosa has been used in patients suffering from cystic fibrosis and chronic pulmonary colonization with this bacterium. Furthermore, IgY has been used to counteract streptococcus mutans in the oral cavity and for the treatment of enteral infections in both humans and animals. However, the use of avian antibodies is limited to pulmonary, enteral, or topical application and should, due to immunogenicity, not be used for systemic administration. Thus, IgY expands the range of strategies available for combating pathogens in medicine, as a promising candidate both as an alternative to antibiotics and as a valuable tool in research and diagnostics. Full article

Wild waterfowl are considered to be the reservoir of avian influenza, but their distinct annual life cycle stages and their contribution to disease dynamics are not well understood. Studies of the highly pathogenic avian influenza (HPAI) virus have primarily focused on wintering grounds, where human and poultry densities are high year-round, compared with breeding grounds, where migratory waterfowl are more isolated. Few if any studies of avian influenza have focused on the molting stage where wild waterfowl congregate in a few selected wetlands and undergo the simultaneous molt of wing and tail feathers during a vulnerable flightless period. The molting stage may be one of the most important periods for the perpetuation of the disease in waterfowl, since during this stage, immunologically naïve young birds and adults freely intermix prior to the fall migration. Our study incorporated empirical data from virological field samplings and markings of Swan Geese (Anser cygnoides) on their breeding grounds in Mongolia in an integrated agent-based model (ABM) that included susceptible–exposed–infectious–recovered (SEIR) states. Our ABM results provided unique insights and indicated that individual movements between different molting wetlands and the transmission rate were the key predictors of HPAI perpetuation. While wetland extent was not a significant predictor of HPAI perpetuation, it had a large effect on the number of infections and associated death toll. Our results indicate that conserving undisturbed habitats for wild waterfowl during the molting stage of the breeding season could reduce the risk of HPAI transmission. Full article

Background: Two high primary-immunization doses of a wild-type E. tenella strain were assessed in healthy pullets (5K versus 10K sporulated oocysts/bird) to understand the effects of coccidia infection. Methods: Acquired immunity was evaluated following primary immunization and two booster doses with the homologous strain. Total oocyst shedding, clinical signs, and viability of every bird/group after each immunization/booster were recorded. Indirect ELISA measured the time course of humoral responses from each immunization group against sporozoite and second-generation merozoite of E. tenella. Antigen pattern recognition on these two asexual zoite stages of E. tenella was analyzed using Western blotting with antibodies from each immunization program. Afterwards, antigen recognition of specific life-cycle stages was performed using individual pullet serums from the best immunization program. Results: A primary-immunization dose of 1 × 10⁴ oocysts/bird reduced the oocyst output; however, all pullets exhibited severe clinical signs and low specific antibodies titers, with decreased polypeptide recognition on both E. tenella asexual zoite stages. In contrast, immunization with 5 × 10³ oocysts/bird yielded the best outcomes regarding increased oocyst collection and early development of sterilizing immunity. After the first booster dosage, this group’s antisera revealed a strong pattern of specific antigen recognition on the two assayed E. tenella life-cycle stages. Conclusions: The E. tenella-specific antibodies from the 5 × 10³ oocysts/bird immunization program can aid in passive immunization trials and further research to identify B-cell immunoprotective antigens, which could help in the development of a genetically modified anticoccidial vaccine. Full article

This study investigates the immunological factors underlying the differential susceptibility of two chicken strains, E- and M-lines, to avian leukosis virus subgroup J (ALV-J). During the eradication of avian leukosis at a chicken breeder farm in Guangdong, we observed strain-specific differences in susceptibility to ALV-J. Moreover, E-line chickens exhibited a slower antibody response to ALV-J compared to M-line chickens. As the T cell receptor (TCR) and B cell receptor (BCR) are critical for antigen recognition, their activation triggers specific immune responses, including antibody production. Using high-throughput sequencing, we characterized the T cell receptor beta (TCRβ) and immunoglobulin heavy chain (IGH) repertoires in spleen tissues from both chicken strains. The M-line demonstrated higher clonal diversity in both TCRβ and IGH repertoires under normal conditions compared to the E-line, suggesting a broader baseline antigen recognition capacity. Following ALV-J infection, the TCRβ repertoire diversity remained unchanged, while the IGH repertoire displayed distinct clonal expansion patterns and complementarity-determining region 3 (CDR3) length distributions between the two lines, potentially affecting their ability to recognize ALV-J antigens. Our study provides the first comprehensive comparison of TCRβ and IGH repertoire dynamics in chickens with different ALV-J susceptibilities, offering new insights into the molecular and immunological mechanisms underlying resistance to ALV-J. Full article

Avian leukosis virus (ALV) is an avian oncogenic retrovirus that can impair immunological function, stunt growth and decrease egg production in avian flocks. The capsid protein (P27) is an attractive candidate for ALV diagnostics. In the present study, a new hybridoma cell (1F8) stably secreting an anti-P27 monoclonal antibody (mAb) was developed. The mAb exhibited a high affinity constant (Ka) of 8.65 × 10^6.0 L/mol, and it could be used for the detection of ALV-A/B/J/K strains. Moreover, a total of eight truncated recombinant proteins and five synthetic polypeptides were utilized for the identification of the B-cell epitopes present on P27. The results revealed that ²¹⁸IIKYVLDRQK²²⁷ was the minimal epitope recognized by 1F8, which had never been reported before. Additionally, the epitopes could strongly react with different ALV subgroup’s specific positive serum and had a complete homology among all the ALV subgroups strains. Finally, a new sandwich ELISA method was created for the detection of ALV antigens, demonstrating increased sensitivity compared to a commercially available ELISA kit. These results offer essential knowledge for further characterizing the antigenic composition of ALV P27 and will facilitate the development of diagnostic reagents for ALV. Full article

Avian coccidiosis, despite advancements in management, nutrition, genetics, and immunology, still remains the most impactful disease, imposing substantial economic losses to the poultry industry. Coccidiosis may strike any avian species, and it may be mild to severe, depending on the pathogenicity of Eimeria spp. and the number of oocysts ingested by the bird. Unlike broilers, low emphasis has been given to laying hens. Coccidiosis in laying hens damages the gastrointestinal tract and causes physiological changes, including oxidative stress, immunosuppression, and inflammatory changes, leading to reduced feed intake and a drastic drop in egg production. Several countries around the world have large numbers of hens raised in cage-free/free-range facilities, and coccidiosis has already become one of the many problems that producers have to face in the future. However, limited research has been conducted on egg-laying hens, and our understanding of the physiological changes following coccidiosis in hens relies heavily on studies conducted on broilers. The aim of this review is to summarize the effect of coccidiosis in laying hens to an extent and correlate it with the physiological changes that occur in broilers following coccidiosis. Additionally, this review tries to explore the nutritional strategies successfully used in broilers to mitigate the negative effects of coccidiosis in improving the gut health and performance of broilers and if they can be used in laying hens. Full article

At the turn of the 21st century, the importance of maintaining a balanced microbiome was brought to the forefront of the microbiology, immunology, and physiology research fields. Exploring the complex interactions between vaccine administration, mucosal microbiome, oral tolerance, and enteric inflammation in health and disease is challenging since environmental factors (such as diet and sanitation) have major influences on gut microbiota composition. High enteric pathogen load has been shown to contribute to dampened cell-mediated and humoral immune responses to vaccines in human case studies, either through elevated enteric inflammation or increased tolerance to environmental microbes. Although antibiotic and probiotic interventions have been evaluated in human health as well as research animal models, effective measures to mediate vaccine hyporesponsiveness are still ill-defined. Research in this field is becoming increasingly important for managing flock health in commercial poultry production, especially as antibiotic-free production is more prevalent and vaccination programs remain extensive during the first weeks of a bird’s life. By understanding the cellular interactions between commensal microbiota, vaccine antigens, and the host immune system (particularly in avian models), advancements in bacterial and viral vaccine immunogenicity could lead to improved flock health in meat-type and egg-type chickens in the future. Full article

Diverse immune responses in different chicken lines can result in varying clinical consequences following avian influenza virus (AIV) infection. We compared two widely used layer breeds, Lohmann Brown (LB) and Lohmann White (LW), to examine virus replication and immune responses against H9N2 AIV infection. The transcription profile in the spleen of H9N2-infected chickens was compared using a microarray. Confirmatory real-time RT-PCR was used to measure the expression of C-type lectin, OASL, and MX1 genes. Additionally, to investigate the role of chicken lectin receptors in vitro, two C-type lectin receptors (CLRs) were expressed in DF-1 cells, and the early growth of the H9N2 virus was evaluated. The LB chickens shed a lower amount of virus from the cloaca compared with the LW chickens. Different expression levels of C-type lectin-like genes were observed in the transcription profile, with no significant differences in OASL or MX gene expression. Real-time RT-PCR indicated a sharp decrease in C-type lectin levels in the spleen of H9N2-infected LW chickens. In vitro studies demonstrated that cells overexpressing CLR exhibited lower virus replication, while silencing of homeostatic CLR had no effect on AIV replication. This study demonstrated distinct immune responses to H9N2 avian influenza in LB and LW chickens, particularly with differences in C-type lectin expression, potentially leading to lower virus shedding in LB chickens. Full article

Four mutants varying the length of the G and SH genes, including a G-truncated mutant (ΔG) and three G/SH-truncated mutants (ΔSH/G-1, ΔSH/G-2, and ΔSH/G-3), were generated via serially passaging the avian metapneumovirus strain SNU21004 into the cell lines Vero E6 and DF-1 and into embryonated chicken eggs. The mutant ΔG particles resembled parental virus particles except for the variance in the density of their surface projections. G and G/SH truncation significantly affected the viral replication in chickens’ tracheal ring culture and in infected chickens but not in the Vero E6 cells. In experimentally infected chickens, mutant ΔG resulted in the restriction of viral replication and the attenuation of the virulence. The mutants ΔG and ΔSH/G-1 upregulated three interleukins (IL-6, IL-12, and IL-18) and three interferons (IFNα, IFNβ, and IFNγ) in infected chickens. In addition, the expression levels of innate immunity-related genes such as Mda5, Rig-I, and Lgp2, in BALB/c mice were also upregulated when compared to the parental virus. Immunologically, the mutant ΔG induced a strong, delayed humoral immune response, while the mutant ΔSH/G-1 induced no humoral immune response. Our findings indicate the potential of the mutant ΔG but not the mutant ΔSH/G-1 as a live attenuated vaccine candidate. Full article

Avian influenza is caused by avian influenza virus infection; the H5N1 avian influenza virus is a highly pathogenic subtype, affecting poultry and human health. Since the discovery of the highly pathogenic subtype of the H5N1 avian influenza virus, it has caused enormous losses to the poultry farming industry. It was recently found that the H5N1 avian influenza virus tends to spread among mammals. Therefore, early rapid detection methods are highly significant for effectively preventing the spread of H5N1. This paper discusses the detection technologies used in the detection of the H5N1 avian influenza virus, including serological detection technology, immunological detection technology, molecular biology detection technology, genetic detection technology, and biosensors. Comparisons of these detection technologies were analyzed, aiming to provide some recommendations for the detection of the H5N1 avian influenza virus. Full article

Among the respiratory pathogens of birds, the Avian Metapneumovirus (aMPV) is one of the most relevant, as it is responsible for causing infections of the upper respiratory tract and may induce respiratory syndromes. aMPV is capable of affecting the reproductive system of birds, directly impacting shell quality and decreasing egg production. Consequently, this infection can cause disorders related to animal welfare and zootechnical losses. The first cases of respiratory syndromes caused by aMPV were described in the 1970s, and today six subtypes (A, B, C, D, and two more new subtypes) have been identified and are widespread in all chicken and turkey-producing countries in the world, causing enormous economic losses for the poultry industry. Conventionally, immunological techniques are used to demonstrate aMPV infection in poultry, however, the identification of aMPV through molecular techniques helped in establishing the traceability of the virus. This review compiles data on the main aMPV subtypes present in different countries; aMPV and bacteria co-infection; vaccination against aMPV and viral selective pressure, highlighting the strategies used to prevent and control respiratory disease; and addresses tools for viral diagnosis and virus genome studies aiming at improving and streamlining pathogen detection and corroborating the development of new vaccines that can effectively protect herds, preventing viral escapes. Full article

Marek’s disease virus (MDV) causes a deadly lymphoproliferative disease in chickens, resulting in huge economic losses in the poultry industry. It has been suggested that MDV suppresses the induction of type I interferons and thus escapes immune control. Cholesterol 25-hydroxylase (CH25H), a gene that encodes an enzyme that catalyses cholesterol to 25-hydroxycholesterol (25-HC), is an interferon-stimulating gene (ISG) known to exert antiviral activities. Other oxysterols, such as 27-hydroxycholesterols (27-HC), have also been shown to exert antiviral activities, and 27-HC is synthesised by the catalysis of cholesterol via the cytochrome P450 enzyme oxidase sterol 27-hydroxylase A1 (CYP27A1). At 24 h post infection (hpi), MDV stimulated a type I interferon (IFN-α) response, which was significantly reduced at 48 and 72 hpi, as detected using the luciferase assay for chicken type I IFNs. Then, using RT-PCR, we demonstrated that chicken type I IFN (IFN-α) upregulates chicken CH25H and CYP27A1 genes in chicken embryo fibroblast (CEF) cells. In parallel, our results demonstrate a moderate and transient upregulation of CH25H at 48 hpi and CYP27A1 at 72hpi in MDV-infected CEF cells. A significant reduction in MDV titer and plaque sizes was observed in CEFs treated with 25-HC or 27-HC in vitro, as demonstrated using a standard plaque assay for MDV. Taken together, our results suggest that 25-HC and 27-HC may be useful antiviral agents to control MDV replication and spread. Full article

Chronic wounds and their treatment present a significant burden to patients and healthcare systems alike, with their management further complicated by bacterial infection. Historically, antibiotics have been deployed to prevent and treat infections, but the emergence of bacterial antimicrobial resistance and the frequent development of biofilms within the wound area necessitates the identification of novel treatment strategies for use within infected chronic wounds. Here, several non-antibiotic compounds, polyhexamethylene biguanide (PHMB), curcumin, retinol, polysorbate 40, ethanol, and D-α-tocopheryl polyethylene glycol succinate 1000 (TPGS) were screened for their antibacterial and antibiofilm capabilities. The minimum inhibitory concentration (MIC) and crystal violet (CV) biofilm clearance against two bacteria frequently associated with infected chronic wounds, Staphylococcus aureus and Pseudomonas aeruginosa, were determined. PHMB was observed to have highly effective antibacterial activity against both bacteria, but its ability to disperse biofilms at MIC levels was variable. Meanwhile, TPGS had limited inhibitory activity but demonstrated potent antibiofilm properties. The subsequent combination of these two compounds in a formulation resulted in a synergistic enhancement of their capability to kill both S. aureus and P. aeruginosa and disperse their biofilms. Collectively, this work highlights the utility of combinatory approaches to the treatment of infected chronic wounds where bacterial colonization and biofilm formation remains significant issues. Full article

Emerging RNA virus infections are a growing concern among domestic poultry industries due to the severe impact they can have on flock health and economic livelihoods. Avian paramyxoviruses (APMV; avulaviruses, AaV) are pathogenic, negative-sense RNA viruses that cause serious infections in the respiratory and central nervous systems. APMV was detected in multiple avian species during the 2017 wild bird migration season in Ukraine and studied using PCR, virus isolation, and sequencing. Of 4090 wild bird samples collected, mostly from southern Ukraine, eleven isolates were grown in ovo and identified for APMV serotype by hemagglutinin inhibition test as: APMV-1, APMV-4, APMV-6, and APMV-7. To build One Health’s capacity to characterize APMV virulence and analyze the potential risks of spillover to immunologically naïve populations, we sequenced virus genomes in veterinary research labs in Ukraine using a nanopore (MinION) platform. RNA was extracted and amplified using a multiplex tiling primer approach to specifically capture full-length APMV-1 (n = 5) and APMV-6 (n = 2) genomes at high read depth. All APMV-1 and APMV-6 fusion (F) proteins possessed a monobasic cleavage site, suggesting these APMVs were likely low virulence, annually circulating strains. Utilization of this low-cost method will identify gaps in viral evolution and circulation in this understudied but important critical region for Eurasia. Full article