Search Results (171)

Coronaviruses, including avian infectious bronchitis virus (IBV), utilize host cellular pathways to evade the host immune response. The aryl hydrocarbon receptor (AhR), a key antiviral regulator exploited by mammalian coronaviruses like SARS-CoV-2, remains unclear in avian coronavirus pathogenesis. This study examined AhR’s involvement during IBV infection using H1299 and Vero cells with pharmacological modulation (AhR antagonist CH223191/agonist kynurenine) and shRNA-mediated silencing. Viral replication was quantified through plaque assays, qRT-PCR, and Western blot. The results reveal IBV-induced AhR activation, driving downstream CYP1A1 expression and pro-inflammatory cytokine production. CH223191 treatment reduced IBV titers, RNA loads, and N protein expression dose-dependently, while kynurenine showed no effect. AhR knockdown similarly reduced N protein expression, confirming its proviral role. An IBV-encoded noncoding RNA was identified as a modulator of AhR activation, suggesting viral balancing of immune evasion and replication efficiency. These results establish AhR as a conserved host factor co-opted by IBV, and highlight AhR antagonism as a promising therapeutic strategy. By bridging insights from avian and mammalian coronaviruses, this work informs strategies to address IBV’s genetic variability and supports development of broad-spectrum antiviral therapies. Full article

Efficient control measures for respiratory diseases in humans and farm animals require accurate, specific, and rapid diagnostics. Traditional PCR-based molecular diagnostics are restricted to centralized laboratories, which results in significant, potentially catastrophic delays in test results. A case in point is the recent avian flu outbreak, which has culled more than 280 million poultry birds worldwide (over 157 million in the USA alone) since 2022; has spread to other farm animals, such as cattle; has further heightened the risk of a human pandemic; and threatens food security. To enable molecular diagnosis of bird respiratory diseases at the point of need, we employ loop-mediated isothermal amplification (LAMP) in two platforms: (A) portable devices linked to a smartphone and (B) an inexpensive, disposable, electricity-free, instrument-free device with closed-tube, colorimetric detection that can be produced with minimal resources. Smartphone integration offers an unexplored opportunity for spatiotemporal disease mapping, equipping policymakers with critical data for outbreak control. Our assays demonstrated 100% sensitivity and specificity compared to the gold standard, lab-based, quantitative PCR (qPCR). We tested contrived samples of the avian flu H5N1 virus, laryngotracheitis virus (ILTV), and infectious bronchitis virus (IBV) spiked into clinical samples, achieving a detection sensitivity adequate for early infection diagnosis in under 45 min. The test is simple, requires minimal training, and can be performed without refrigeration, making it well-suited for resource-limited settings. Full article

Newcastle disease (ND) is a highly contagious and economically significant viral infection that affects poultry globally, with recurrent outbreaks occurring even among vaccinated flocks in Egypt. Caused by the Newcastle disease virus (NDV), the disease results in substantial losses due to high mortality rates, decreased productivity, and the imposition of trade restrictions. This study aimed to develop a rapid, sensitive, and field-deployable diagnostic assay based on real-time reverse transcription recombinase-aided amplification (RT-RAA) for the detection of all NDV genotypes in clinical avian specimens. Primers and an exo-probe were designed based on the most conserved region of the NDV matrix gene. After testing ten primer combinations, the pair NDV RAA-F1 and RAA-R5 demonstrated the highest sensitivity, detecting as low as 6.89 EID₅₀/mL (95% CI). The RT-RAA assay showed excellent clinical sensitivity and specificity, with no cross-reactivity to other common respiratory pathogens such as avian influenza virus, infectious bronchitis virus, Mycoplasma gallisepticum or infectious laryngotracheitis virus. All 25 field samples that were tested positive by real-time RT-PCR, including those with high CT values (~35), were detected by RT-RAA in 2–11 min, indicating superior sensitivity and speed. The assay requires only basic equipment and can be performed under isothermal conditions, making it highly suitable for on-site detection in resource-limited or rural settings. The successful implementation of RT-RAA can improve NDV outbreak response, support timely vaccination strategies, and enhance disease control efforts. Overall, the assay presents a promising alternative to conventional diagnostic methods, contributing to the sustainability and productivity of the poultry sector in endemic regions. Full article

The infectious bronchitis virus (IBV) causes a severe infectious disease in poultry, leading to significant financial losses. The prevention and treatment of this disease are extremely challenging due to the virus’s rapid mutation. Therefore, quick diagnosis of IBV infections is crucial for controlling the disease. This study aimed to develop a real-time reverse transcription recombinase-aided amplification (RT-RAA) method for IBV. The most effective primer combination was selected for further validation. To determine the assay’s analytical sensitivity, a serial dilution from 10⁵ to 10⁰ EID₅₀/mL was used, and the limit of detection was calculated. The assay could detect down to 10² EID₅₀/mL. The limit of detection (95% Confidence Interval) was 67 EID₅₀ per reaction. There was no cross-reaction with common poultry diseases. When analyzing 39 clinical samples, RT-RAA and RT-PCR showed 100% diagnostic sensitivity and specificity. In conclusion, the IBV RT-RAA detection method is rapid, sensitive, and specific. This approach can be used to improve IBV diagnosis at the point of need. Full article

The molecular basis for the distinct intestinal tropism of infectious bronchitis virus (IBV) strains remains poorly understood. This study identifies the S2 subunit of the spike glycoprotein as the critical determinant conferring duodenal tropism to the IBV CSL strain. Comparative pathogenesis in specific-pathogen-free (SPF) chicks revealed that the CSL strain achieved significantly higher viral titers in the duodenum compared to strains D90, PYG QX1, and XXX QX5. This duodenal replication was associated with severe epithelial inflammation, characterized by upregulation of pro-inflammatory cytokines (IL-6, IL-17A, IL-22, TNF-α, IFN-β, IFN-γ) and disruption of barrier integrity via downregulation of tight junction proteins (Occludin, Claudin-1, ZO-1). Crucially, reverse genetics using the non-enterotropic D90 backbone demonstrated that recombinant viruses carrying the CSL-S2 gene (rD90-ΔS/CSL and rD90-ΔS2/CSL), but not those carrying CSL-S1 (rD90-ΔS1/CSL), replicated efficiently and induced inflammation in the duodenum, phenocopying wild-type CSL. In contrast, renal tropism was independent of the S2 subunit. These findings establish the S2 subunit as both necessary and sufficient for IBV duodenal tropism, uncoupling it from renal pathogenicity. This identifies S2 as a prime molecular target for developing next-generation vaccines against intestinal IBV pathotypes. Full article

IBV is a key pathogenic agent in poultry, causing significant respiratory and renal diseases. This study investigated NLRP3 inflammasome and pyroptosis involvement in IBV-infected chicken macrophage HD11 cells. IBV infection triggered a time-dependent increase in the release of IL-1β/IL-18, along with the upregulation of inflammasome-related genes. MCC950 treatment, an NLRP3 inhibitor, notably decreased inflammatory markers while enhancing viral replication, highlighting the NLRP3 inflammasome’s function in restricting viral proliferation and mediating immunopathology. Experiments with UV-inactivated IBV demonstrated that active viral replication was essential for inflammasome activation. Pyroptosis was confirmed in IBV-infected HD11 cells through increased LDH release, characteristic ultrastructural damage, and upregulation of pyroptosis-related genes. Additionally, transfection with the IBV nucleocapsid (N) gene alone induced inflammasome activation and pyroptosis, indicating that the N protein is a key viral factor in this process. Our study offers a new understanding of IBV pathogenesis mechanisms and indicates that targeting the NLRP3 inflammasome may serve as a therapeutic approach. Full article

Infectious bronchitis virus (IBV) remains a major threat to poultry health worldwide due to frequent genetic changes mainly driven by recombination and limited cross-protection between genotypes. In this study, we analyzed IBV strains collected from clinical outbreaks in Chile between 1986 and 2021 to assess the long-term impacts of live-attenuated vaccines (Massachusetts and 4/91) on viral evolution. Phylogenetic analysis of the S1 and N genes revealed four major lineages circulating in Chile—GI-1, GI-13, GI-16, and a novel monophyletic clade we propose as GI-31. The latter, identified in isolates from 1986 to 1988, is highly divergent (22–24%) from other known lineages, representing a previously unreported South American IBV variant. Despite widespread Mass vaccination, genetically distinct field strains circulated during the 1980s, facilitating potential recombination with GI-1 vaccine-derived strains, including evidence of shared ancestry with GI-11, an endemic lineage from Brazil. Non-recombinant GI-16, likely introduced from Asia, was detected in isolates from 2009. Notably, a recombinant strain emerged in 2015, four years after 4/91 vaccine introduction, indicating vaccine–field-strain genetic exchange. By 2017, isolates with >99% identity to the 4/91 strain were recovered, suggesting vaccine-derived variants. In 2021, GI-1 re-emerged, showing recombination signatures between GI-1 and GI-13 (4/91-derived) strains, likely reflecting suboptimal or inconsistent vaccination strategies. Selection analyses showed strong purifying selection across most of the S1 gene, with limited sites under positive selection in the receptor-binding domain. Phylodynamic reconstruction revealed time-structured evolution and multiple introduction events over 35 years, with lineage-specific tMRCA estimates. Collectively, these findings highlight the emergence of a novel lineage in South America and demonstrate that vaccine use, while mitigating disease, has significantly shaped the evolution of IBV in Chile. Our results underscore the importance of continuous genomic surveillance to inform vaccine strategies and limit recombinant emergence. Full article

Backyard production systems (BPSs) are common in Chile and play an important role in food access and local trade. However, these systems often lack basic biosecurity and disease prevention practices, which increases the risk of disease spreading. In this study, we evaluated the presence of two major avian respiratory viruses, infectious bronchitis virus (IBV) and infectious laryngotracheitis virus (ILTV), in BPSs located near wetlands in central Chile. These areas are known as the country’s main poultry production zones. We collected 449 poultry serum samples from 88 BPSs and performed serological tests using ELISA. Additionally, we analyzed 250 poultry tracheal swabs from 31 BPSs using qPCR. The results showed high seroprevalence levels: 95.5% of BPSs tested positive for IBV and 85.2% for ILTV. At the animal level, 82.2% were positive for IBV and 57.2% for ILTV. Most birds had antibodies to both viruses. However, active infections were less frequent, with 4.3% of tracheal swabs testing positive for IBV and 14.1% for ILTV during 2021 and 0.6% and 3.8% for IBV and ILTV, respectively, during 2024. This is the first serological and molecular evidence of IBV and ILTV circulation in backyard poultry in central Chile. Since this region includes most of the country’s poultry industry, these findings raise concern about the risk of virus transmission to commercial farms. The high circulation rates suggest that backyard poultry could act as reservoirs and may contribute to decreased productivity. Our results highlight the need for improved disease surveillance and enhancement of biosecurity in BPSs in Chile. Full article

Background: Infectious bronchitis virus (IBV) is a gammacoronavirus that causes a highly contagious disease in chickens and seriously endangers the poultry industry. The GI-19 is a predominant lineage. However, no effective commercially available vaccines against this virus are available. Methods: In this present study, the CHO eukaryotic and the E.coli prokaryotic expression system were used to express S1-SpyTag and AP205-SpyCatcher, respectively. Subsequently, the purified S1-SpyTag and AP205-SpyCatcher were coupled to form the nanoparticles AP205-S1 (nAP205-S1) in PBS buffer at 4 °C for 48 h. S1-SpyTag and nAP205-S1 were formulated into vaccines with white oil adjuvant and employed to immunize 1-day-old SPF chickens for the comparative evaluation of their immune efficacy. Results: The nAP205-S1 vaccine in chickens induced robust IBV-specific humoral and cellular immune responses in vivo. Importantly, the humoral and cellular immune responses elicited by the nAP205-S1 vaccine were more robust than those induced by the IBV S1-SpyTag vaccine at both the same dose and double the dose, with a notably significant difference observed in the cellular immune response. Furthermore, experimental data revealed that chicken flocks vaccinated with nAP205-S1 achieved 100% group protection following a challenge, exhibiting a potent protective immune response and effectively inhibiting viral shedding. Conclusions: These results reveal the potential of developing a novel nanoparticle vaccine with broadly protective immunity against GI-19 IBV. Full article

Objectives: Our objective was to investigate the clinical characteristics, complications, and treatment outcomes of Epstein–Barr virus (EBV)-related infectious mononucleosis (IM) in children and to identify risk factors associated with prolonged fever and abnormal liver function. Methods: This retrospective study included 3006 children admitted to Shenzhen Children’s Hospital from May 2009 to April 2024 with suspected EBV-related IM. After excluding cases without etiological evidence and those with underlying diseases, 2660 cases were analyzed. Data on demographics, clinical manifestations, laboratory findings, complications, and treatment outcomes were collected. Logistic regression was used to identify risk factors for prolonged fever and abnormal liver function. Results: Among the 2660 confirmed cases, patients ranged from 8 months to 17 years of age, with a median age of 4 years and a male-to-female ratio of 1.46:1. Co-infections were identified in 369 (13.9%) patients, predominantly with Group A Streptococcus. Complications occurred in 560 (24.46%) of the 2289 patients without co-infections, with bronchitis being the most common (42.68%). Elevated ferritin and atypical lymphocyte percentage were associated with prolonged fever (p < 0.001), while elevated lactate dehydrogenase (LDH) and a lower CD4% predicted abnormal liver function (p < 0.001). Antiviral therapy did not shorten fever duration or hospital stay but prolonged both when combined with corticosteroids or intravenous immunoglobulin (IVIG) (p < 0.001). Conclusions: Specific laboratory markers such as ferritin, atypical lymphocyte percentage, LDH, and CD4% are important predictors of prolonged fever or liver dysfunction in EBV-IM. Our findings suggest that antiviral therapy may not be beneficial in uncomplicated cases and highlight the need for tailored treatment strategies to optimize patient outcomes. Full article

Avian infectious bronchitis virus (IBV) infection has caused significant economic losses to the poultry industry. Unfortunately, there is currently no effective cure for this disease. Understanding the pathogenic mechanism is crucial for the treatment of the disease. Studying the pathogenic mechanism of IBV based on metabolomics analysis is helpful for identifying antiviral drugs. However, studies on metabolomics analysis of IBV infection have been relatively limited, particularly without metabolomics analysis in sera after IBV infection. In this study, 17-day-old SPF chicks were infected with the IBV GX-YL5 strain, and serum samples were collected 7 days post-infection (DPI) for metabolomics analysis using ultraperformance liquid chromatography tandem mass spectrometry (UPLC-MS/MS). A total of 143 differential metabolites were identified across 20 metabolic pathways, with the phenylalanine pathway showing the most significant changes. The level of cinnamic acid (CA), an upstream metabolite in the phenylalanine pathway, was notably increased following IBV infection. To investigate the antiviral effects of CA, chicken embryo kidney (CEK) cells and SPF chicks infected with IBV were treated with different concentrations of CA to assess its effect on viral replication. The results demonstrated that CA at 25 μg/mL effectively inhibited IBV replication in vitro; meanwhile, CA at 50 μg/mL and 25 μg/mL effectively inhibited IBV replication in vivo. Molecular docking and molecular dynamics simulation studies showed that CA interacts with the N domains of the IBV nucleocapsid (N) protein. In conclusion, the serum metabolite CA is significantly elevated following IBV infection and demonstrates remarkable antiviral effects both in vitro and in vivo, providing a promising avenue for the development of antiviral therapies to combat IBV infection. Full article

Infectious bronchitis virus (IBV) and low-pathogenic avian influenza virus (LPAIV) H9N2 are commonly identified in poultry, individually or in association with other pathogens. This study monitored 183 broiler farms affected by respiratory diseases across seven regions of Morocco from January 2021 to December 2023. Among these farms, 87.98% were vaccinated against IBV, while 57.92% were against AI H9N2. Abnormally high mortality rates were observed in 44.26% of the farms, with 24.69% of cases attributed to IBV, 50.62% to LPAI H9N2, and 13.58% due to coinfection with both IBV and H9N2. RT-PCR analysis of tissue samples and cloacal and tracheal swabs collected from 183 broiler farms revealed that 33.33% were positive for IBV and 34.97% for H9N2. Coinfection by IBV and H9N2 was detected in 12.57% of cases, peaking at 17% in 2022. Co-infected flocks exhibited severe clinical signs and lesions, such as reduced food consumption, diarrhea, and renal issues. The predominant lesions were in the respiratory tract, affecting 91.26% of infected broilers. Additionally, among the 183 flocks, 50 farms that tested positive for IBV infection were randomly selected from the seven regions of Morocco for further investigation of other respiratory pathogens, including Mycoplasma gallisepticum (MG), Mycoplasma synoviae (MS), and infectious laryngotracheitis (ILT), using real-time RT-PCR. Detection rates for these pathogens were 26% for MG, 30% for MS, 4% for ILTv (vaccine strain), and 18% for ILTw (wild strain). Detection rates for single, dual, triple, and quadruple infections were 34%, 42%, 18%, and 4%, respectively. The most common dual and triple coinfections were IBV + H9N2 (14%) and IBV + MG + MS (10%). Phylogenetic analysis of the S gene identified two main IBV genotypes, namely, 793B and D181, with the latter being a strain circulating for the first time in Moroccan poultry. This underscores the urgent need to establish surveillance systems to track pathogen circulation and implement strategies to control virus spread, ensuring the protection of animals and public health. Full article

Infectious bronchitis virus (IBV) is a coronavirus first isolated in the 1930s infecting chickens. IBV causes great economic losses to the global poultry industry, as it affects egg production and causes mortality by leaving the host susceptible to secondary bacterial infections. Even though vaccines are available, they are poorly cross-protective against new variants of the virus, which are always on the cusp of emerging. Effective antiviral therapies, or possibly the production of transgenic animals immune to IBV infection, are therefore sorely needed. As the papain-like protease (PLpro) of IBV has deubiquitinating activity besides its crucial ability to cleave the viral polyprotein, we have applied a novel strategy of selecting ubiquitin variants (UbVs) from a phage-displayed library that have high affinity to this viral protease. These UbVs were found to inhibit the deubiquitinating activity of PLpro and consequently obstruct the virus’s ability to evade the innate immune response in the host cell. By obstructing the proteolytic activity of PLpro, these UbVs were seemingly able to inhibit viral infection as assessed using immunofluorescence microscopy. Whilst virus infection was detected in around 5% of UbV-expressing cells, the virus was present in around 30–40% of GFP (control)-expressing cells. This suggests that the expression of UbVs indeed seems to inhibit IBV infection, making UbVs a potentially potent and innovative antiviral strategy in the quest for control of IBV infections. Full article

Background: Live attenuated and inactivated virus vaccines are commonly used against infectious bronchitis virus (IBV) in chickens, but they have limitations such as mutation risks and short efficacy. This study explores cationic bovine serum albumin (BSA) polyamine nanoparticles (NPs) for delivering IBV spike protein mRNA, aiming to develop a safer and more effective vaccine. Methods: A BSA-based nanoparticle system was designed with positive surface charges and characterized using dynamic light scattering (DLS), Zetasizer, and transmission electron microscopy (TEM). Its cytotoxicity, cellular uptake, and ability to deliver IBV spike protein mRNA were evaluated in macrophage-like chicken cell lines (HD11), followed by immunogenicity studies in SPF chickens to assess immune responses. Results: The study demonstrated successful binding and transfection efficiency of the in vitro transcription (IVT)-mRNA complexed with the NPs, which was enhanced with chloroquine. Immunogenicity studies in SPF chickens showed a significant increase in antibody titers in chickens vaccinated with the mRNA vaccine compared to the PBS control, indicating an effective immune response against the IBV S protein. Furthermore, the neutralization index doubled after a higher-dose mRNA booster with chloroquine, and PBMCs from immunized chickens exhibited a threefold higher stimulation index than the PBS control. Conclusions: BSA-based NPs effectively deliver IBV spike protein mRNA, enhancing immune responses and offering a promising strategy for a safer, more effective IBV vaccine. Full article

Infectious bronchitis virus (IBV) is a chicken pathogen present in commercial poultry farms worldwide. It is classified within the species Avian coronavirus, genus Gammacoronavirus. As with other members of the family Coronaviridae, it has a single positive-sense RNA genome with 27.6 Kb and presents viral particles with a typical crown-like aspect due to the spike (S) transmembrane glycoprotein. IBV has a remarkable capacity for genetic recombination and mutation, resulting in many genotypes and antigenic variants over evolutionary time. Currently, it is classified into nine genetic types (GI to GIX) and 41 (1 to 41) lineages disseminated worldwide. In South America, IBV was first identified in early commercial poultry production ventures in Brazil in the 1950s. Since then, this virus has been frequently detected in commercial South American poultry farms, being classified into serotypes in the first decades and genotypes more recently. IBVs of the Massachusetts (Mass) serotype were initially detected and vaccine strains of this serotype were used extensively on commercial poultry farms. Other serotypes/genotypes were identified later, with almost all of them classified in the current genetic type I (GI). In addition, five GI lineages (GI-1, -11, -13, -16, and -23) have been associated with the main infectious bronchitis outbreaks in the continent, with some variations in the occurrence according to the countries and the period of time. Molecular epidemiological surveillance of IBV genetic types and lineages is necessary to anticipate potential outbreaks, revealing patterns of viral evolution and dissemination, as well as to guide the selection of appropriate vaccine strains and immunization programs. Full article