Avian Infectious Bronchitis Virus (IBV) is a highly contagious Gammacoronavirus that poses a significant threat to the global poultry industry. Despite its worldwide prevalence, a critical knowledge gap exists regarding the genetic diversity of IBV in Central Asia, particularly in Uzbekistan. This study is the first comprehensive molecular characterization of IBV in Uzbekistan. This study also provides a unique and informative bioinformatic analysis of the detected strains. Three IBV strains were isolated and identified from chickens suspected of IBV infection. The isolates were identified and subjected to S1 gene sequencing, phylogenetic analysis, recombination screening, selective pressure mapping, and in silico structural and antigenic profiling. Phylogenetic inference revealed that the isolates clustered within the established genotypes GI-1, GI-13, and GI-23. Comparative alignments revealed distinct nucleotide and amino acid substitutions relative to global reference strains. The evolutionary patterns are consistent with a predominantly clonal mode of evolution. Structural modeling and B-cell epitope prediction revealed pronounced antigenic and topological divergence among the Uzbek isolates. Genotype-specific substitutions, particularly in solvent-exposed regions of the spike protein, were associated with altered epitope profiles, implying potential impacts on vaccine cross-protection. These findings contribute to current knowledge of IBV molecular characterization and provide the first reference framework for the Central Asian region. The study highlights the importance of continuous molecular surveillance, region-specific vaccination strategies, and integrated genomic monitoring for novel IBV variants.

Molecular Detection and Phylogenetic Characterization of Avian Infectious Bronchitis Virus (IBV) in Vaccinated Commercial Chicken Flocks Experiencing Outbreaks in Faisalabad, Pakistan.

Forsythoside A inhibits avian infectious bronchitis virus infection by binding the S1 subunit.

Coronaviruses evolve rapidly, with recombination and mutation fostering the emergence of variant strains. The avian coronavirus infectious bronchitis virus (IBV) is an important poultry pathogen and a valuable natural model for studying coronaviruses. Australian strains have evolved independently of those infecting chickens elsewhere in the world, so understanding the biology and evolution of these strains can further our understanding of factors driving the emergence of novel coronaviruses. We infected groups of specific pathogen-free Leghorn chickens with six Australian IBVs (from five distinct genotypes) isolated between 1962 and 2013. All six affected the respiratory tract, but only one was nephropathogenic (N1/62). All six induced significant lesions and actively replicated in the upper respiratory tract, but they had lower levels of replication and induced less severe lesions in the middle and lower trachea. There were significant differences between the six strains in the severity of the lesions they induced and in their tissue tropism and effect on tracheal ciliary motility. Strains N1/62 (strain T) and N1/03 caused the most severe tracheal ciliostasis and replicated to the highest levels in tissues. Strain N1/03 caused the most severe lesions at 9 days post-infection. Only strain N1/03 caused lesions in the lower trachea. Overall, strains N1/03 and N1/62 were the most virulent. This study is the first to characterize the histological changes induced by the recently isolated Australian IBVs and compare them directly with older strains. Recombination between field and vaccine strains of IBV has yielded emergent IBVs in Australia that appear to have enhanced virulence for the respiratory tract.

ABSTRACT Avian infectious bronchitis virus (IBV) belongs to the genus Gammacoronavirus (family Coronaviridae), causes severe multi-system disease in chickens, inflicting major global economic losses. The molecular interplay between IBV and host metabolic networks remains poorly understood. Through integrated transcriptomic, metabolomic, and lipidomic profiling of oviduct tissues from specific-pathogen-free (SPF) chickens infected with the IBV QXL strain, we demonstrate tripartite metabolic reprogramming: 1) redirected glucose flux through the pentose phosphate pathway (PPP) to fuel nucleotide synthesis, 2) rewired lipid metabolism to prioritize de novo membrane biogenesis over fatty acid β-oxidation, and 3) orchestrated glycerophospholipid remodeling. This integrated analysis revealed a coordinated upregulation of fatty-acid biosynthesis genes and accumulation of specific glycerophospholipids and eicosanoids. Mechanistically, IBV co-opts the Warburg effect and PPP activation while uniquely suppressing fatty acid β-oxidation to channel fatty acids toward lipid droplets (LDs) biogenesis. Phosphatidylserine (PS) overproduction (e.g. 2.55-fold increase in PS(22:0/22:6)) and phospholipase A2 (PLA2)-mediated lysophospholipids (Lyso-PLs) and eicosanoids generation (e.g. 7.09-fold increase in prostaglandin E2 (PGE2)) emerged as critical regulators of membrane dynamics and inflammatory signaling. This process was centrally coordinated by the significant activation of peroxisome proliferator-activated receptor (PPAR) (e.g. 1.74-fold increase in ACSL1) and transforming growth factor-beta (TGF-β) (e.g. significant increase in p-SMAD2) signaling pathways, directly linking lipid remodeling to immunomodulation. Functionally, targeting acetyl-CoA carboxylase (ACC) or glucose-6-phosphate dehydrogenase (G6PD), alongside TGF-β pathway modulation, synergistically curtailed viral replication in vitro. Our findings delineate a critical PPAR-TGF-β cross-talk that governs lipid remodeling during infection and identify host metabolic nodes that are potentially targetable for antiviral intervention.

Abstract Avian infectious bronchitis virus (IBV), a gammacoronavirus with substantial agricultural impact, offers a tractable model for dissecting coronavirus evolution. Here, we integrated 20 years of epidemiological surveillance with whole‐genome sequence analysis of 624 IBV strains, including 136 newly isolated field samples, to investigate the evolutionary and structural dynamics of N‐linked glycosylation at the spike protein. We identified three dominant glycosylation haplotypes defined by residues 51 and 77 of spike protein, which correlate with receptor‐binding interfaces, clinical phenotypes, and spatiotemporal transmission patterns. Molecular modeling and docking analyses provided insights into potential mechanistic links between glycan positioning and Neu5Acα2‐3Galβ1‐3GlcNAc receptor engagement. Complementing these findings, we developed a proof‐of‐concept machine learning model that shows potential for predicting clinical serotypes directly from the spike protein sequence, achieving high accuracy on a preliminary independent validation set. These findings support the use of glycosylation motifs as structural‐genomic markers and highlight the potential of sequence‐based serotype prediction. Our work establishes a scalable genomic‐structural framework that leverages glycosylation motifs and sequence features as evolutionary markers, providing a powerful approach for forecasting coronavirus adaptation and informing vaccine design and outbreak preparedness.

Avian infectious bronchitis virus (IBV) is a major pathogen impacting the global poultry industry. The QX genotype (GI-19 lineage) of IBV has rapidly spread worldwide and is now the dominant genotype in Asia and Europe. In this study, three QX-type field strains (JS/773, JS/774, and SD/783) were isolated from diseased chicken flocks in eastern China, which had been vaccinated with IBV live attenuated vaccines (H120 or QXL87) between December 2024 and January 2025. Notably, the JS/773 strain showed an H536P mutation at the S protein cleavage site, marking the first identification of a PRRRR cleavage motif in this lineage and highlighting the diversity of cleavage sites among QX-type strains. Recombination analysis showed that these isolates are recombinant variants from vaccine strains 4/91, H120, and QXL87, as well as circulating field strains, with recombination occurring in the ORF1a/ORF1b, ORF5a/ORF5b and M regions. Pathogenicity testing in SPF chickens demonstrated that the isolates induced marked lesions in the respiratory and urinary systems; however, JS/773 caused the most severe tissue damage and resulted in the highest mortality rate among the groups. Cross-neutralization assays revealed substantial antigenic differences between the isolates and the H120 strain, and with reduced antigenic relatedness to the QXL87 strain. Seven amino acid mutations occurred in the isolates S1 subunit neutralizing epitope region, altering protein conformation and potentially contributing to antigenic variation and immune evasion. In conclusion, the genetic traits and pathogenicity of these isolates highlight the evolving QX-type strains in China, that offers new insights into the molecular evolution of QX-type IBV antigenicity.Supplementary InformationThe online version contains supplementary material available at 10.1186/s12917-025-05224-7.

Background/Objective: The poultry industry requires extensive vaccination of chickens against IBV in an effort to prevent the disease in animals and significant economic losses. Current vaccination strategies often lack effectiveness, and the continual emergence of new IBV variants makes disease control increasingly challenging. We have developed an inactivated vaccine for poultry containing nine different antigens (Nobilis Multriva), including two IBDV strains, two ARV strains, one NDV strain, one AMPV strain, one EDSV strain and two IBV strains: M41 (genotype GI-1) and 4–91 (genotype GI-13). In this study, the IB efficacy of this novel inactivated vaccine was investigated against homologous and heterologous IBV strains. Methods: Inactivated IBV vaccine containing the M41 and 4–91 strains (Nobilis Multriva) was administered intramuscularly, either alone or following vaccine priming, in SPF and commercial chickens. Birds were challenged with homologous and heterologous IBV strains at defined ages (peak of lay, mid-lay and end of lay). Vaccine efficacy was evaluated through serological assays, clinical observations, and monitoring of egg production post-challenge. Results: This vaccine provided excellent broad protection against different IBV strains circulating in different parts of the world, including IBV M41, 4–91, QX, Q1 and Var2. Furthermore, the vaccine provided long-lasting IBV serological response against IB M41 and IB 4–91 until at least 96 weeks of age in SPF and commercial layers and breeder birds. This vaccine will allow farmers to reduce the number of vaccination moments, thereby minimizing stress to the birds, while also decreasing labor demands and the risk of human error, ultimately contributing to lower overall vaccination costs. Conclusions: Given its demonstrated broad cross-protection and sustained serological responses, this nine-valent inactivated vaccine (Nobilis Multriva) represents a key component of an effective vaccination regimen for controlling IBV infections in the poultry industry.

Newcastle disease (ND) and avian infectious bronchitis (IB) continue to be a major problem for the poultry industry but can be controlled with effective vaccination programs. Vaccination of 1-day-old chicks with Newcastle disease and IB vaccines plays an important role in the immunization of flocks, and the immune response is one of the most interesting discussions in avian immunology that could be carried out with monovalent or polyvalent vaccines. Eighty 1-day-old specific pathogen-free chicks were divided into four groups (n = 20 per group) and immunized via eye drops with Newcastle disease, Newcastle disease/infectious bronchitis, and Newcastle disease + infectious bronchitis vaccines. The fourth group, the control group, received no vaccine. Forty-eight hours after vaccination, samples were taken from the Harderian’s gland and RNA was extracted. The expression level of eight cytokines (interleukin-1, 6, 8, 10, 12, 15, 18, and interferon) was analyzed by quantitative real-time polymerase chain reaction. According to the results, the highest gene expression in response to the Newcastle disease vaccine was observed for interleukins 10, 12, and 15. The expression of interleukins 1, 6, 8, 18, and interferon-alpha also increased against the Newcastle disease/infectious bronchitis vaccine. According to the results, the commercial Newcastle disease/infectious bronchitis vaccine, a factory-mixed vaccine of two viruses, was able to induce a stronger local and inflammatory cytokine response than the separate vaccination with Newcastle disease and Newcastle disease + infectious bronchitis, resulting in higher innate immunity. Cite this article as: Hajitabar, A., Shayegh, J., Hosseini, H., Hosseinzadeh, S., & Ghalyanchilangeroudi, A. (2025). Evaluation of innate immune response of mono and polyvalent newcastle disease vaccines with infectious bronchitis vaccines in day-old chickens. Acta Veterinaria Eurasia, 2025, 51, 0084, doi:10.5152/actavet.2025.25084.

Avian infectious bronchitis virus (IBV) is one of the most prevalent viral diseases in industrial poultry farming and is characterized by high genetic variability of the pathogen. Due to its ability to rapidly mutate and recombine, the virus constantly generates new genetic variants, complicating diagnosis, prevention, epizootic control, and classification. Representatives of different IBV genotypes are important in veterinary virology, vaccination strategies, and epidemiological monitoring. The aim of this review article is to describe the classification of IBV genetic lineages based on genetic and phylogenetic studies, to examine the global and Ukrainian distribution of the main genotypes, and to substantiate the need for monitoring circulating strains in poultry farms. The study systematizes data on known IBV lineages, including the newly identified genotypes GVII, GVIII, and GIX. Current data indicate that IBV strains are classified into nine major genotypes (GI–GIX), comprising a total of 41 genetic lineages. The largest genotype, GI, includes 31 lineages, while others such as GII, GIII, and GIV are represented by one or two lineages each. Literature analysis revealed that the most widespread genetic lineages are Massachusetts (GI-1), 793B (GI-13), QX (GI-19), and Variant 2 (GI-23), which dominate in different regions of the world. In Ukraine, the circulation of strains 4/91 (793B), Variant 2, QX, Mass, and D274 has been confirmed. The article highlights the considerable genetic variability of IBV and its global distribution. The implementation of an IBV monitoring and control system is essential for effective disease prevention and minimizing economic losses.

The online version contains supplementary material available at 10.1007/s13337-025-00945-7.

Background: As infectious bronchitis virus (IBV) strains similar to the IBV S95 live attenuated vaccine strain have been occasionally detected in poultry farms in Japan, we investigated the suspicion that outbreaks of the disease were related to the S95 vaccine. Methods: We isolated ten S95 vaccine-like strains, classified in the JP-I genotype of S1, the VIb (Y-4) genogroup of S2, and the GI-18 lineage, from IBV-affected chickens in Japan between 2020 and 2024. The whole-genome sequence and adaptation to embryonated chicken eggs were investigated. We developed a method for distinguishing the S95 vaccine strain from S95-like wild-type strains using specific primer sets having either the S95 vaccine or S95 parent-specific nucleotide at the 3′ termini of primers on the ORF2 gene. Results: Nine of ten S95 vaccine-like strains lacked identical mutations to the ORF1ab, ORF2, and ORF5a genes that the S95 vaccine strain acquired during attenuation. The remaining S95-like strain, B3389, had identical mutations to the S95 vaccine strain in the ORF1ab and ORF5a genes. The B3389 strain, however, had strain-specific nucleotides that were not found in the S95 vaccine or S95 parent strains, and produced fewer embryonated egg-adapted phenotypes than the S95 vaccine strain. Conclusions: The ten S95-like strains appear not to have emerged from the S95 vaccine strain. Instead, sporadic outbreaks of S95 vaccine-like IBV strains in Japan were indicated. A method for distinguishing and excluding the S95-like wild-type strains as suspected revertants of the S95 vaccine may be utilized for comprehensive IBV surveillance to facilitate development of a vaccination strategy.

Avian infectious bronchitis virus (IBV) is a globally prevalent and highly contagious avian pathogen that imposes significant disease burden and economic losses on the poultry industry. Given the challenges associated with current vaccine-based immunization strategies, there is an urgent need to develop novel therapeutic approaches for the prevention and treatment of IBV infection. In this study, a newly synthesized compound, N-phenethylphenazine-1-carboxamide (SQXA-12), was evaluated for its potent inhibitory effects on IBV replication. The cytotoxicity assay revealed CC50 values of 151.2 µM in H1299 cells, 147.0 µM in Vero cells, 96.83 µM in DF-1 cells, 166.6 µM in HeLa cells, and 136.7 µM in Mac-145 cells, while the EC50 value of SQXA-12 was determined to be 12.25 µM. Sensitivity tests against a panel of viruses, including vesicular stomatitis virus (VSV), human coronavirus OC43 (HCoV-OC43), porcine epidemic diarrhea virus (PEDV), Newcastle disease virus (NDV), porcine reproductive and respiratory syndrome virus (PRRSV), and avian influenza virus H9N2 (AIV-H9N2), demonstrated that SQXA-12 exhibits potential broad-spectrum antiviral activity against both positive- and negative-sense RNA viruses. Collectively, these findings underscore the promising therapeutic potential of SQXA-12 for the treatment of IBV infection.

Infectious diseases caused by pathogenic microorganisms have caused serious economic losses to animal husbandry, and the use of appropriate disinfectants is crucial for eliminating these pathogens. Plant essential oils (PEOs), as natural bioproducts, have the characteristics of safety, non-toxicity, and broad spectrum. In this study, the inhibition efficacies against bacteria, viruses, and mycoplasmas of a compound PEO disinfectant (designated as Lei-Huo-Fu) were evaluated through determination of minimum inhibitory concentration (MIC) and bactericidal rate against Escherichia coli, Staphylococcus aureus, and Salmonella spp.; inactivation rate of avian infectious bronchitis virus (IBV); as well as determination of MIC of Mycoplasma gallisepticum (MG) and Mycoplasma synoviae (MS). The results showed that the MIC values of the PEO disinfectant against Escherichia coli, Staphylococcus, and Salmonella spp. were as low as 0.00375 µg/mL to 0.03 µg/mL. The bactericidal rates against Escherichia coli, Staphylococcus aureus, and Salmonella spp. reached over 95% within 30 min at a concentration of 0.03 µg/mL. For three dominant prevalent genotype strains of LX4-type, Mass-type, and Taiwan-type of IBV, the inactivation rates achieved by the PEO disinfectant at a concentration of 0.015 µg/mL and a disinfection time of 30 min were all above 99.9%. The MIC of the PEO disinfectant against MG and MS was 0.001875 µg/mL and 0.00375 µg/mL, respectively. In conclusion, the compound PEO disinfectant (Lei-Huo-Fu) has significant inhibitory effects on bacteria, viruses, and mycoplasmas, and possesses broad-spectrum antimicrobial activity. However, it is important to note that these findings are based on laboratory assays, and the efficacy in practical settings, along with the exact mechanisms of action, require further investigation. In this study, the compound PEO disinfectant demonstrates promising in vitro efficacy, suggesting its potential as a candidate for development into a safe, efficient, and natural disinfectant, pending further validation.

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.

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.

Infectious bronchitis (IB) is an acute and highly contagious respiratory, renal, and reproductive organ infection of chickens. Infectious bronchitis virus (IBV) that replicates in epithelial cells of the trachea resulting in respiratory signs (sneezing, cough, tracheal rales, gasping and nasal discharge. This study was carried out to monitor Infectious bronchitis virus (IBV) infection in local disease outbreaks in Khyber Pakhtunkhwa (KP), Pakistan. A total of 57 chickens (broilers & layers) were examined for the presence of IBV. Tissue samples were screened through reverse transcriptase PCR (RT-PCR) to detect IBV S- glycoprotein gene (surface glycoprotein gene) and to amplify the hypervariable region of the S1-glycoprotein gene. Ten samples were found to be positive for the infectious bronchitis virus (IBV) after the initial PCR screening from the original 57 samples. An expected approximately 298bp band was noticed in detection of RT-PCRs. The samples found to be positive by the detection of PCR were further processed for the genotyping RT-PCR of the S1 gene. An approximately 700 bp band was seen in all the 10 cases. The bands were gel-purified and then sent for DNA sequencing. HKY model for Neighbour joining with 1000 bootstrap replicates in Program Geneious (10.2.3 version) was used to construct a phylogenetic tree. Next, we performed amino acid sequence alignment of these positive samples with the amino acid sequences of the previously reported two sequences of the S-1 gene of M41(Massachusetts 41) strain in Pakistan which were used in Phylogenetic analysis. This revealed that 4 sample amino acid sequences were closely related (93-100%) with Pakistan reported IBV sequences (KY588135 and KU145467). Our current study of IBV isolates revealed an identity of 60% with the isolates reported from China, 30% identity with the isolates reported in Pakistan and 10% identity with the isolates reported from India

A new method for testing avian metapneumovirus vaccine efficacy: Evaluation of tracheal ciliary activity after a challenge.

Currently, the study of coronavirus infections, including those in birds, is relevant. The virus mainly replicates in the epithelial cells of the respiratory tract, causing lower respiratory tract infections in chickens. At the same time, virus replication in the intestine plays a key role in the development of coronavirus infection. In this study, the localization of preferential replication of the avian infectious bronchitis virus was studied based on the assessment of the ratio of genomic and subgenomic RNA of the AIB virus in the lungs, thymus and intestine. To model the avian infectious bronchitis, 14-day-old Shaver cross chickens were inoculated with a 10-fold dose of the vaccine strain of the avian infectious bronchitis (strain Ma5, serotype Massachusetts). During pathological examination, the thymus, intestine and lungs were collected for polymerase chain reaction (RT-PCR). The ratio of genomic and subgenomic RNA in the thymus, lungs and intestine was estimated as the ratio of threshold cycles in PCR for genomic RNA to threshold cycles for subgenomic RNA. Subgenomic RNA is formed directly in the infected cells. If there is more subgenomic RNA in the studied organ than genomic RNA, this may indicate active replication of the virus in this place. It has been proven that the source of the virus in the thymus is the replication process, and not hematogenous transport. A statistically significant prevalence of subgenomic RNA in the intestine (p ≤ 0.05) has been established, which indicates active replication of the coronavirus in the intestine and the predominant formation of a pool of viral particles in the lungs by the hematogenous and lymphogenous pathways.

Lipid nanoparticles-mRNA play important roles in SARS-CoV-2 infection control. Avian coronavirus infectious bronchitis virus (IBV) comprises eight genotypes with a lack of cross-protection, causing severe economic losses to the poultry industry. Using immunoinformatics methods, five consensus sequence antigens against prevalent IBV strains were designed. Four monovalent lipid nanoparticles-mRNA (GI-19, GI-13, GI-7, GVI-1) and one quadrivalent lipid nanoparticles-mRNA were constructed to develop a broad-spectrum IBV vaccine. The safety and biodistribution of the lipid nanoparticles-mRNA were evaluated in SPF chickens and confirmed that it induced a strong and durable immune response. The lipid nanoparticles-mRNA efficacy in SPF chickens was verified in infection assays with four genotypes of IBV strains, the results showed that immunization with a 10 µg dose provided complete protection for the chickens, while immunization with a 5 µg dose reduced disease severity, organ damage, and mortality, and inhibited viral replication and shedding. Our results indicate that these Lipid nanoparticles-mRNA are immunogenic and protective in preclinical animal models. These data can provide a basis for IBV prevention and control and the development of mRNA vaccines against other prevalent viruses.Graphical abstract