miR-17195 promotes infectious bronchitis virus proliferation and macrophage-mediated inflammation via the PLCβ2-TAK1 axis.

Research note: Virome of Alectoris chukars by metagenomic analysis in Guangdong, southern China.

Insights into antiviral activity of chlorpromazine against RNA viruses: Molecular docking, ADME profile, and semi-in vivo study.

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

Research progress and applications of reverse genetics systems for infectious bronchitis virus.

Infectious bronchitis virus (IBV) causes a highly contagious disease in chickens. The prevalence of GVI-1 is increasing; however, the genomic characteristics and antigenic properties of this genotype strain remain insufficiently characterized. In this study, the genome characteristics and antigenic properties of a naturally attenuated CK/CH/SC/YC_GVI-1-DK/LMB20210104 (abbreviated as YC_GVI-1) strain were systematically analyzed. YC_GVI-1 occupies a distinct phylogenetic lineage and shares a similarity of 98.2%, the highest nucleotide sequence homology, with the reference strain CK/CH/FJ/202005 (accession number: MW791835.1). This strain was likely originated through a genetic recombination event between two major parental strains, CK/CH/FJ/202005 and CK/CH/GX/HX (accession number: PP817796.1). However, its S protein harbors ten unique amino acid substitutions, compared to the same protein in the other two virulent strains in the same genotype. AlphaFold3-based structural prediction reveals that one of these substitutions, methionine 485 to valine substitution, may induce a conformational change in the adjacent phenylalanine residue at position 431, resulting in a shift in the local secondary structure from β-sheet to random coil. Characterization of its antigenicity showed that this strain induces a strong humoral immune response, with neutralizing antibody titers of 26.40 against homologous strain YC_GVI-1 and 24.00 against heterologous strain JS96_GI-19. Furthermore, vaccination of chickens with this strain conferred complete protection (100%) against JS96_GI-19. The findings provide novel insights into the molecular evolution and antigenicity of YC_GVI-1, offering key information for improving IBV surveillance and vaccine development.

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.

The rapid evolution of coronaviruses (CoVs) requires researchers to develop specific yet broad-spectrum detection methods to monitor their constant genomic changes. The goal of the present study was to establish a current pan-coronavirus RT-PCR system capable of detecting a wide variety of CoVs and useful for the investigation of virus diversity and host spectrum. For optimization, one-step and two-step nested RT-PCRs with three RT enzymes were examined, amplifying a ~600 bp long product of the RNA-dependent RNA polymerase. As templates, the in vitro transcribed RNA of ten pathogenic CoVs (SARS-CoV, SARS-CoV-2, NL-63, OC43, feline CoV, porcine epidemic diarrhea virus or PEDV, transmissible gastroenteritis virus or TGEV, canine CoV, bat CoV, and infectious bronchitis virus) were applied instead of the often-used DNA standards. A limit of detection of 5–50 copies/reaction was achieved with a random hexamer-primed two-step RT-PCR and a touchdown cycling profile, representing a lower detection limit and higher specificity compared to previously published primer sets. Swine origin pooled samples (n = 121), collected from apparently healthy herds in Hungary, were tested with the novel RT-PCR system. Sequences of porcine respiratory CoV/TGEV and porcine hemagglutinating encephalomyelitis virus were identified in 24 oral fluid and nasal swab pools, demonstrating the circulation of these viruses in this country, as well as the suitability of the new PCR for their detection. The results highlighted the importance of adequate RT enzyme selection and the use of RNase inhibitors in sample preparation and conservation.

Infectious Bronchitis Virus is one of several major viral infections in poultry, affecting the respiratory, reproductive, and renal systems and causing significant economic losses worldwide. Current vaccines, including the H120 strain, provide limited cross-protection against emerging variants, underscoring the need for improved vaccine strategies. In this study, the complete genome of IBV H120 was divided into 12 fragments, synthesized, and assembled using the Golden Gate Assembly (GGA) method. The recombinant virus (rH120) was successfully rescued in chicken fibroblast cells and propagated in embryonated specific-pathogen-free (SPF) chicken eggs. Growth kinetics in embryonated SPF chicken eggs revealed similar replication patterns between rH120 and the original H120 strain. In broiler chickens, rH120 replicated efficiently, as confirmed by viral RNA detection in throat and cloacal swabs, and induced a stronger antibody response by 14 days post-infection. The rH120 virus proved to be genetically stable, infectious, and immunogenic, indicating that GGA-based reverse genetics is an effective system for IBV vaccine development.

Avian influenza, caused by the avian influenza A virus (IAV), threatens poultry and public health. H6 subtype avian IAV is a low-pathogenic virus with hosts ranging from poultry and wild birds to mammals. H6 persists latently in poultry, which enables silent transmission and cross-species risk. The few fluorescence quantification assays that exist for H6 are mostly multiplexed. We developed a rapid, sensitive, efficient, monoplex fluorescence reverse-transcription qPCR (RT-qPCR) assay for H6 IAV. Specific primers and a TaqMan-MGB probe were designed based on the conserved hemagglutinin (HA) gene region of H6 IAVs from the GISAID database. The reaction components and conditions were optimized, and the assay was evaluated for specificity, sensitivity, and reproducibility. The optimized assay had excellent specificity, with no cross-reactivity with other avian viruses, including IAV subtypes H1-5, H7, H9, and H10, Newcastle disease virus, infectious bronchitis virus, fowl adenovirus, infectious laryngotracheitis virus, chicken anemia virus, Mycoplasmopsis (Mycoplasma) gallisepticum, and M. synoviae. Our method had a detection limit of 8.2 × 100 copies/μL, which is 1,000 times more sensitive than conventional RT-PCR. The intra- and inter-assay CVs for all tested concentrations were both <1.5%, indicating good reproducibility. When applied to clinical swab samples, the sensitivity of our fluorescence RT-qPCR assay was 98.8% and specificity was 96.2% compared with traditional virus isolation. Our method could provide strong technical support for the early detection, monitoring, and prevention of H6 subtype IAV infection.

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.

Enhanced oral bioavailability and antiviral efficacy of phillygenin via a self-nanoemulsifying drug delivery system in IBV-infected broilers

Infectious bronchitis virus is one of the most important economic viral diseases of poultry that is spreading worldwide, affects both gallinaceous and non-gallinaceous birds. Avian Pathogenic Escherichia coli (APEC), classified under the extra-intestinal pathogenic E. coli (ExPEC) category which causes various syndromes in poultry including systemic and localized infections. Infectious bronchitis and E. coli diseases caused by pathogens are considered infectious or contagious because they can be transmitted from poultry to poultry through direct and indirect routes. According to their pathogenic microorganism, they can be biologically classified into viruses, bacteria, fungi, parasites and protozoa. There was total of “Ross strain” chicks used in this study was 21000, (1.523) chickens died resulting in an overall mortality rate of (7.5%) chicken. There were changes in clinical symptoms that occur in broiler chickens aged 10-15 days. These changes include respiratory signs such as difficulty breathing, cough, depression, and decreased appetite. There were changes in post mortem that occur in broiler chickens aged 12, 16 and 31 days. Those changes include mild congestion in the trachea at (12 day of age), congestion in the lung at (16 days of age), nodules and thick surface in the proventriculus and mild congestion in the ileocecal junction at (31 days of age), the lesions that appear were suspected of the infectious bronchitis disease. The study was conducted to determine the prevalence and incidence of an Infectious bronchitis and E. coli pathogens of significant economic importance in broiler farm at Kirkuk City, Iraq. At the end, the results obtained from this work also confirm the suitability of postmortem changes in infectious bronchitis virus and E. coli bacteria included mild congestion in the trachea and proventiculus, also fibrinous peri-hepatitis and pericarditis in broiler chicks.

Influence of drinking water quality on immune responses to viral vaccines in layer chickens.

An epidemiological study on the prevalence and associated risk factors of infectious bronchitis virus in poultry farms in northern Vietnam.

The epidemiological situation in Poland for IBV GII (formerly known as D1466) has seemed stable over the years, but an increase in such infections has been recently reported. In this study, genetic characterization of the representatives of this genotype was performed in order to determine whether the new epidemic wave of GII IBV was responsible for changes in this status quo. Genotyping based on the complete S1 coding region of eight Polish IBV field strains from 2011 to 2021 confirmed that they belonged to genotype II, with two of them clustered in the two previously identified GII-1 and GII-2 lineages. In turn, the S1 coding region sequences of the next six Polish strains are very different from the previous ones and form a separate group on the phylogenetic tree. However, comprehensive analysis of all complete S1 coding regions of GII strains did not fulfill all parameters needed to create the separate GII lineage, and they all seem to belong to the GII-1 lineage. Further analysis of the partial S1 sequence of 15 IBV GII strains showed their genetic distinctiveness and indicates the ongoing evolution of this virus genotype. Considering the results of our study and the recent outbreaks of GII-2 in Western Europe, it appears that infections with GII virus strains mainly affect egg-producing, long-lived chickens, commercial layers, and breeders. Furthermore, due to the high diversity of these viruses, their circulation in the poultry population may remain undetected, and for this reason, the observed production problems in laying flocks may be attributed to other, unrelated factors.

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., &amp; 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.

In vivo studies in chickens demonstrate that the activation of the NLRP3 inflammasome is a key driver of renal injury during infectious bronchitis virus (IBV) infection. Pharmacological inhibition of NLRP3 significantly alleviates renal inflammation and tissue damage without affecting viral replication, highlighting the central role of host inflammatory responses in disease progression. Importantly, we report for the first time that NLRP3 activation is predominantly localized to AQP2-positive collecting ducts, a nephron segment essential for uric acid excretion and electrolyte balance. IBV infection reprograms these epithelial cells into a pro-inflammatory, metabolically dysregulated state, promoting urate crystal formation and amplifying tissue injury. These findings reveal a spatially confined epithelial-immune axis of coronavirus-induced renal pathology and suggest new avenues for targeted intervention.