Infectious Bronchitis Virus Research Articles

Characterization of predominant genotype (QX) of avian infectious bronchitis virus isolated from layer chickens in Bangladesh

Avian infectious bronchitis (AIB) is a highly transmissible infection that affects the poultry industry globally. This study aims to isolate and characterize emerging strains of infectious bronchitis virus (IBV) from field samples of layer chickens in Bangladesh. A total of 108 samples (trachea, lung, and kidney) were taken from dead and sick layer chickens from 18 farms in 4 areas detecting outbreaks in Bangladesh. The samples were processed and inoculated in embryonated chicken eggs (ECEs) and finally screened by the trypsin-induced hemagglutination (THA) test. Using various techniques such as hemagglutination inhibition (HI), agar gel immuno-diffusion (AGID), virus neutralization test (VNT), reverse transcription-polymerase chain reaction (RT-PCR), and nucleotide sequencing, we were able to identify and confirm the isolated IBV viruses. The study also determined the hemagglutination (HA) pattern of isolated virus using avian and mammalian red blood cells. The pathogenicity of the isolated IBV was determined using embryonated chicken eggs and day-old chicks. The study found that 8 samples were positive for IBV using ECEs, and 4 were positive by the THA test. These isolates were confirmed using HI, AGID, and VN tests. S1 gene-based RT-PCR confirmed all four isolates as IBV, with the recent isolates belonging to the genotype-QX and being similar to IBV isolates from Thailand, Saudi Arabia, and India. The HA pattern of the recent isolates showed that the isolated IBV was virulent. The pathogenicity test also revealed that the four isolates were highly pathogenic. The study indicated that the prevalent genotype (QX) of the IBV strain is present in the layer chicken population of Bangladesh.

The N545S and K717N substitution at the N-glycosylation sites of the S2 subunit of avian infectious bronchitis virus can significantly enhance viral pathogenicity

The S2 subunit of infectious bronchitis virus (IBV) is a heavily glycosylated protein that can impact various characteristics of the virus. It is currently known that N-glycosylation modifications are predominantly located on the S2 subunit. However, the exact role of their N-glycosylation modification remains undisclosed. To elucidate the function of these N-glycosylation sites, we identified 14 common sites distributed on the S2 subunit of the 5 genotypes of IBV in present study. Subsequently, we selected 7 sites to generate mutants and assessed their impact on viral virulence, replication ability, and antigenicity. Our finding revealed that only 2 substitutions, N545S and K717N, increased the viral replication titer and antigenicity, and ultimately the pathogenicity in chicks. To delve into the mechanisms underlying this increased pathogenicity, we discovered that K717N can change the structure of antigenic epitopes. The N545S substitution not only influenced antigenic epitope structure, but also enhanced the ability of the virus to enter CEKs during the early stages of viral replication. These results suggest that the enhanced viral pathogenicity associated with N545S and K717N substitutions is multifaceted, with acceleration of the viral membrane fusion process and alterations in epitope structure representing crucial factors in the capability of N-glycosylation modifications to boost viral virulence. These insights provide valuable guidance for the efficient development of live attenuated vaccines.

Co-infection of H9N2 subtype avian influenza virus and QX genotype live attenuated infectious bronchitis virus increase the pathogenicity in SPF chickens

Avian influenza virus (AIV) infection and vaccination against live attenuated infectious bronchitis virus (aIBV) are frequent in poultry worldwide. Here, we evaluated the clinical effect of H9N2 subtype AIV and QX genotype aIBV co-infection in specific-pathogen-free (SPF) white leghorn chickens and explored the potential mechanisms underlying the observed effects using by 4D-FastDIA-based proteomics. The results showed that co-infection of H9N2 AIV and QX aIBV increased mortality and suppressed the growth of SPF chickens. In particular, severe lesions in the kidneys and slight respiratory signs similar to the symptoms of virulent QX IBV infection were observed in some co-infected chickens, with no such clinical signs observed in single-infected chickens. The replication of H9N2 AIV was significantly enhanced in both the trachea and kidneys, whereas there was only a slight effect on the replication of the QX aIBV. Proteomics analysis showed that the IL-17 signaling pathway was one of the unique pathways enriched in co-infected chickens compared to single infected-chickens. A series of metabolism and immune response-related pathways linked with co-infection were also significantly enriched. Moreover, co-infection of the two pathogens resulted in the enrichment of the negative regulation of telomerase activity. Collectively, our study supports the synergistic effect of the two pathogens, and pointed out that aIBV vaccines might increased IBV-associated lesions due to pathogenic co-infections. Exacerbation of the pathogenicity and mortality in H9N2 AIV and QX aIBV co-infected chickens possibly occurred because of an increase in H9N2 AIV replication, the regulation of telomerase activity, and the disturbance of cell metabolism and the immune system.

Adding yeast extract to culture medium enhances replication of the avian coronavirus infectious bronchitis virus in chicken embryo kidney cells

Infectious bronchitis virus (IBV), an avian coronavirus, can be isolated and cultured in tracheal organ cultures (TOCs), embryonated eggs and cell cultures, the first two of which are commonly used for viral isolation. Previous studies have suggested that foetal bovine serum (FBS) can inhibit coronavirus replication in cell cultures. In this study, the replication of IBV in chicken embryo kidney (CEK) cell cultures and the Leghorn hepatocellular carcinoma (LMH) cell line was assessed using two different cell culture media containing FBS or yeast extract (YE) and two different IBV strains. The highest concentrations of viral genomes were observed when the cell culture medium (CEK) contained YE. Similar results were observed in LMH cells. Examination of the infectivity by titration demonstrated that the cell lysate from CEK cell cultures in a medium including YE contained a higher median embryo infectious dose than that from CEK cell cultures in a medium containing FBS. These results indicate that improved replication of IBV in cell cultures can be achieved by replacing FBS with YE in the cell culture medium.

Glycerides of lauric acid supplementation in the chicken diet enhances the humoral and cellular immune response to infectious bronchitis virus

Controlling pathogenic infections while reducing antibiotic usage is an important challenge during poultry production. In addition to vaccination strategies, several solutions to enhance the immune response against pathogens are evaluated. In this study, we aim to determine the effects of the glycerides of lauric acid (GLA) supplementation in chickens’ diets on humoral and cellular immune response pathogenic infections, using an in vivo model of infectious bronchitis virus (IBV). One-day-old Ross 308 broilers were vaccinated with live attenuated IBV and fed diets supplemented with or without GLA at 3 kg/ton. The levels of early (day 7) specific anti-IBV in sera were significantly increased in broilers fed GLA, compared to the control groups (P<0.05), showing a stronger primary humoral response. The secretion levels of main cytokines remained similar in spleens of all the experimental groups. However, the splenocytes from broilers fed GLA showed higher activation and effector abilities when measured by IFN-γ ELISpot in presence of N-261–280 IBV peptide or Concanavalin A (Con A), a pan T lymphocytes mitogen. In response to N-261–280 peptide, GLA group showed a 2-fold increase of spot numbers (P < 0.05) and 3-fold increase of spot surfaces (P < 0.01) compared to the control groups. Similarly, Con A stimulation showed a 2-fold increases in spot surfaces and numbers in the GLA supplemented group compared to the control group (P < 0.01). In summary, GLA supplementation in chicken feed enhances the primary humoral immune response and strengthen the T lymphocytes mediated cellular immune response. These findings demonstrate how GLA can improve chicken resilience against pathogenic challenges by enhancing their immune responses.

Antiviral and cytotoxic activities and chemical profiles of two species of Abies nordmanniana from Türkiye.

Abies is an important genus of the family Pinaceae, with about 50 species found in the highlands of Asia, Europe, North Africa, and North and Central America. The principal aim of the present work was to investigate the chemical content and biological potential of the resin and cone from Abies nordmanniana subsp. bornmulleriana and Abies nordmanniana subsp. equi-trojani, respectively. The flavonoid and phenolic contents of the resin and cones were evaluated using liquid chromatography-high resolution mass spectrometry (LC-HRMS). Additionally, the essential oil and fatty acid compositions were analyzed using gas chromatography-mass spectrometry (GC-MS) and gas chromatography-flame ionization detector (GC-FID), respectively. Cytotoxicity of the extracts and essential oils were screened against certain cancer cell lines, namely, human prostate adenocarcinoma cell line (PC3), human lung adenocarcinoma cell line (A549), human pancreatic cancer cell line (PANC-1), human hepatocellular carcinoma cell line (HepG2), human breast cancer cell line (MDA-MB231), and normal human lung fibroblast cell line (CCD-34-LU), with MTT [3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyl-2H-tetrazolium bromide] assay. According to the MTT results, hexane extracts of both cone (CH) and resin (RH), ethanol-water (CEW), dichloromethane (CD), and acetone (CA) extracts of the cone mostly inflict cytotoxicity in HepG2 cell line. Antiviral activities of Abies nordmanniana subsp. extracts at doses of 5 μg/g and 10 μg/g were also evaluated in ovo for their virucidal activity against avian coronavirus. Abies nordmanniana subsp. extracts exhibited concentration-dependent antiviral activity on specific pathogen-free embryonated chicken eggs. Significantly, cone acetone extract (CA), cone ethanol extract (CE), and cone dichloromethane extract (CD) of Abies nordmanniana subsp. exhibited strong inhibition of the virus at a concentration of 10 μg/g. The most potent virucidal activity was observed with ethanol-water extract of conifer form (CEW). According to these results, it was proved that Abies nordmanniana species could be a potential, sustainable, and renewable drug source, especially considering the impressive antiviral and significant cytotoxic activity potentials.

Experimental co–infection of infectious bronchitis and low pathogenic avian influenza viruses (H9N2) aggravates morbidity and mortality in commercial broiler chickens

Experimental co–infection of infectious bronchitis and low pathogenic avian influenza viruses (H9N2) aggravates morbidity and mortality in commercial broiler chickens

Prevalence, Genotype Diversity, and Distinct Pathogenicity of 205 Gammacoronavirus Infectious Bronchitis Virus Isolates in China during 2019-2023.

Gammacoronavirus infectious bronchitis virus (IBV) causes a highly contagious disease in chickens and seriously endangers the poultry industry. The emergence and co-circulation of diverse IBV serotypes and genotypes with distinct pathogenicity worldwide pose a serious challenge to the development of effective intervention measures. In this study, we report the epidemic trends of IBV in China from 2019 to 2023 and a comparative analysis on the antigenic characteristics and pathogenicity of isolates among major prevalent lineages. Phylogenetic and recombination analyses based on the nucleotide sequences of the spike (S) 1 gene clustered a total of 205 isolates into twelve distinct lineages, with GI-19 as a predominant lineage (61.77 ± 4.56%) exhibiting an overall increasing trend over the past five years, and demonstrated that a majority of the variants were derived from gene recombination events. Further characterization of the growth and pathogenic properties of six representative isolates from different lineages classified four out of the six isolates as nephropathogenic types with mortality rates in one-day-old SPF chickens varying from 20-60%, one as a respiratory type with weak virulence, and one as a naturally occurring avirulent strain. Taken together, our findings illuminate the epidemic trends, prevalence, recombination, and pathogenicity of current IBV strains in China, providing key information for further strengthening the surveillance and pathogenicity studies of IBV.

Molecular epidemiology of infectious bronchitis virus in eastern and southern China during 2021–2023

As a highly infectious and contagious pathogen in chickens, infectious bronchitis virus (IBV) is currently grouped into nine genotypes (GI to GIX). However, the classification of serotypes of IBV is still not clear. In this study, 270 field strains of IBV were isolated from dead or diseased chicken flocks in eastern and southern China during Jan. 2021-Apr. 2023. These isolated IBV strains could be classified into two genotypes, GI (including five lineages GI-1, GI-13, GI-19, GI-22 and GI-28) and GVI based on the complete S1 sequence. Further analysis showed that the GI-19, GI-13, GI-22, GI-28 and GVI were the dominant genotypes with the proportions of 61.48%, 8.89%, 8.89%, 7.78% and 8.89% respectively, and the homology of S1 protein of these isolates ranged from 86.85% to 100% in GI-19, 92.22% to 100% in GI-13, 83.1% to 100% in GI-22, 94.81% to 100% in GI-28 and 90.0% to 99.8% in GVI, respectively. Moreover, cross-neutralization test with sera revealed that these isolates in GI-19 lineage could be classified into at least three serotypes according to the antigenic relationship. In addition, structure assay using PyMOL indicated that one mutation such as S120 in receptor binding site (RBD) of GI-19 might alter the antigenicity and conformation of S protein of IBV. Overall, our data demonstrate that not only multiple genotypes, but also multiple serotypes in a single genotype or lineage have been co-circulated in eastern and southern China, providing novel insights into the molecular evolution of the antigenicity of IBV and highlighting the significance of the selection of the dominant isolate for vaccine development in IBV endemic region.

Complete S1 glycoprotein analysis of two distinct groups of GI-19 (QX) infectious bronchitis virus from Indonesia: Molecular phylogenetic and in-silico approaches

Infectious bronchitis (IB) is an important viral disease that impacts poultry productivity, according to many studies. The main important infectious bronchitis virus (IBV) protein, spike glycoprotein subunit 1 (S1), plays a role in pathogenicity and immunogenicity. Conventional molecular detection and analysis of the S1 gene still face many challenges due to its hypervariability. In Indonesia, there were only a few reports on partial S1 gene analysis of IBVs; thus far, there have been no phylogenetic or in-silico approaches to their S1 complete gene. This study aims to reveal molecular pathogenicity and immunogenicity features on the S1 complete gene of IBVs from Indonesia. We analyzed fourteen IBV isolates using conventional RT-PCR and Sanger sequencing and then aligned their verified S1 complete sequences with other Indonesian GI-19 IBVs from Genbank for molecular phylogenetic and in-silico analysis. Phylogenetic analysis consisted of amino acid polymorphism and identity, as well as phylogenetic tree construction. As part of the in-silico analysis, we used proteins that have homology and immunoinformatic predictions (B-cell epitope and N-glycosylation). Molecular phylogenetic analysis revealed the division of the Indonesian GI-19 IBVs into two distinct groups. These groups had different amino acid variations at receptor binding sites, hypervariable antigenic sites, and cleavage sites. We also calculated the amino acid identity at 95.4–98.3%. In-silico studies revealed significant similarities in B-cell epitopes, distinct N-glycosylation sites, and the suggestion of a homotrimer protein structure. We found that the S1 full gene of two different groups of GI-19 IBVs (QX strain) from Indonesia predicted changes in their pathogenicity and immunogenicity.

Genetic evolution and phylogenetic analysis of Infectious Bronchitis Virus circulating in broiler flocks in New Valley Governorate, Egypt

Genetic evolution and phylogenetic analysis of Infectious Bronchitis Virus circulating in broiler flocks in New Valley Governorate, Egypt

Heterologous maternal antibodies derived from infectious bronchitis vaccines prevent the development of lesions associated with false layer syndrome

Infectious bronchitis virus (IBV) strains of the Delmarva (DMV)/1639 genotype have been causing false layer syndrome (FLS) in the Eastern Canadian layer operations since the end of 2015. FLS is characterized by the development of cystic oviducts in layer pullets infected at an early age. Currently, there are no homologous vaccines for the control of this IBV genotype. Our previous research showed that a heterologous vaccination regimen incorporating Massachusetts (Mass) and Connecticut (Conn) IBV types protects layers against DMV/1639 genotype IBV. The aim of this study was to investigate the role of maternal antibodies conferred by breeders received the same vaccination regimen in the protection against the development of DMV/1639-induced FLS in pullets. Maternal antibody-positive (MA+) and maternal antibody-negative (MA−) female progeny chicks were challenged at 1 day of age and kept under observation for 16 weeks. Oviductal cystic formations were observed in 3 of 14 birds (21.4 %) in the MA− pullets, while the lesions were notably absent in the MA+ pullets. Milder histopathological lesions were observed in the examined tissues of the MA+ pullets. However, the maternal derived immunity failed to demonstrate protection against the damage to the tracheal ciliary activity, viral shedding, and viral tissue distribution. Overall, this study underscores the limitations of maternal derived immunity in preventing certain aspects of viral pathogenesis, emphasizing the need for comprehensive strategies to address different aspects of IBV infection.

Synergistic effects of oral inoculation with a recombinant Lactobacillus plantarum NC8 strain co-expressing interleukin-2 and interleukin-17B on the efficacy of the infectious bronchitis vaccine in chickens

Mucosal vaccination strategies are easier to implement than others in large-scale poultry farming. However, the adjuvants that are approved for veterinary use, which are predominantly aluminum- and oil-emulsion-based adjuvants, are not suitable for mucosal vaccination and carry a risk of adverse reactions. In this study, we engineered a novel Lactobacillus plantarum NC8 strain that co-expresses chicken interleukin-2 (IL-2) and IL-17B, which we designated NC8-ChIL2-17B, and evaluated its potential as an oral immunoadjuvant. The immunomodulatory properties of NC8-ChIL2-17B were evidenced by its ability to activate macrophages and inhibit the proliferation of infectious bronchitis virus (IBV) in vitro. We then confirmed its immunoadjuvant activity in vivo by orally administering NC8-ChIL2-17B along with a commercial IBV vaccine to chicks. The results indicated that NC8-ChIL2-17B enhanced the immune response elicited by the IBV vaccine and increased the levels of IBV-specific IgG and sIgA antibodies produced in response to IBV infection. Additionally, administration of NC8-ChIL2-17B promoted weight gain and beneficially modulated the gut microbiota, resulting in improved chicken performance. These findings suggest that oral administration of NC8-ChIL2-17B is a promising strategy to enhance the immune efficacy of the IBV vaccine in chickens, offering an efficacious alternative adjuvant.

Designing and Evaluation of a Multiepitope Vaccine against Avian Newcastle Disease Virus, Influenza Virus and Infectious Bronchitis Virus

<b>Designing and Evaluation of a Multiepitope Vaccine against Avian Newcastle Disease Virus, Influenza Virus and Infectious Bronchitis Virus</b>

Development and application of a cycleave dual-probe fluorescence quantitative PCR method for simultaneous detection of Mycoplasma gallisepticum ts-11 vaccine strain and non-ts-11 strains

An attenuated vaccine against the Mycoplasma gallisepticum ts-11 strain has become an effective prevention and control method against MG infection. However, the ts-11 strain is usually difficult to distinguish from the non-ts-11 strain (including field isolates and other vaccine strains (F and 6/85)). Therefore, it is critical to establish a rapid and effective method to distinguish ts-11 strains from non-ts-11 strains. The gene sequences of the ts-11 strain (CP044225.1) and the non-ts-11 strain (including the wild-type (CP006916.3), 6/85 (CP044224.1), and F strains (NC_017503.1) were used to construct a conserved region containing a single point mutation in the potC gene in the ts-11 strain, after which a primer-probe combination method was designed. The primer-probe method was able to accurately and efficiently identify the ts-11 and non-ts-11 strains with minimum detection limits of 2.43 copies/μL and 1.65 copies/μL, respectively. Moreover, it could simultaneously distinguish the ts-11 strain from a non-ts-11 strain, and amplifications of avian influenza virus, infectious bronchitis virus, Newcastle disease virus, fowl adenovirus, infectious laryngotracheitis virus, infectious bursal disease virus, chicken anemia virus, Marek's disease virus, Mycoplasma synoviae, and Ornithobacter rhinotracheale were negative. The detection of clinical samples revealed that the established dual-probe fluorescence quantitative PCR method could be used to screen for mixed and single infections of the ts-11 strain and non-ts-11 strains effectively, with lower variation coefficients for intra- and interbatch repetition. The established cycleave dual-probe fluorescence quantitative PCR method showed good specificity, sensitivity, and repeatability and provides powerful technical support for the rapid and efficient differential diagnosis of the MG ts-11 strain from non-ts-11 strains.

A novel highly virulent nephropathogenic QX-like infectious bronchitis virus originating from recombination of GI-13 and GI-19 genotype strains in China

Infectious bronchitis virus (IBV) is one of the most widely spread RNA viruses, causing respiratory, renal, and intestinal damage, as well as decreased reproductive performance in hens, leading to significant economic losses in the poultry industry. In this study, a new IBV strain designated as CK/CH/GX/LA/071423 was successfully isolated from the 60-day-old Three-Yellow chicken vaccinated with H120 and QXL87 vaccines. The complete genome sequence analysis revealed that the CK/CH/GX/LA/071423 strain shared a high similarity of 96.7% with the YX10 strain belonging to the GI-19 genotype. Genetic evolution analysis based on the IBV S1 gene showed that the CK/CH/GX/LA/071423 isolate belonged to the GI-19 genotype. Recombination analysis of the virus genome using RDP and Simplot software indicated that CK/CH/GX/LA/071423 was derived from recombination events between the YX10 and 4/91 vaccine strains, which was supported by phylogenetic analysis using gene sequences from the 3 regions. Furthermore, the S1 protein tertiary structure differences were observed between the CK/CH/GX/LA/071423 and the QXL87 and H120 vaccine strains. Pathogenicity studies revealed that the CK/CH/GX/LA/071423 caused death and led to pale and enlarged kidneys with abundant urate deposits, indicative of a nephropathogenic IBV strain. High virus titers were detected in the trachea, kidneys, and cecal tonsils, demonstrating broad tissue tropism. Throughout the experimental period, the virus positive rate in throat swabs of the infected group reached to 100%. These findings highlight the continued predominance of the QX genotype IBV in Guangxi of China and the ongoing evolution of different genotypes through genetic recombination, raising concerns about the efficacy of current IBV vaccines in providing effective protection to poultry.

Infectious bronchitis virus: an overview of the "chicken coronavirus".

Infectious bronchitis virus (IBV) is a highly contagious avian Gammacoronavirus that affects mainly chickens (Gallus gallus) but can circulate in other avian species. IBV constitutes a significant threat to the poultry industry, causing reduced egg yield, growth and mortality levels that can vary in impact. The virus can be transmitted horizontally by inhalation or direct/indirect contact with infected birds or contaminated fomites, vehicles, farm personnel and litter (Figure 1). The error-prone viral polymerase and recombination mechanisms mean diverse viral population results, with multiple genotypes, serotypes, pathotypes and protectotypes. This significantly complicates control and mitigation strategies based on vigilance in biosecurity and the deployment of vaccination.

Establishment of a rapid real-time fluorescence-based recombinase-aided amplification method for detection of avian infectious bronchitis virus

Infectious bronchitis (IB) is an acute, highly contagious contact respiratory disease of chickens caused by infectious bronchitis virus (IBV). IBV is very prone to mutation, which brings great difficulties to the prevention and control of the disease. Therefore, there is a pressing need for a method that is fast, sensitive, specific, and convenient for detecting IBV. In this study, a real-time fluorescence-based recombinase-aided amplification (RF-RAA) method was established. Primers and probe were designed based on the conserved regions of the IBV M gene and the reaction concentrations were optimized, then the specificity, sensitivity, and reproducibility of this assay were tested. The results showed that the RF-RAA method could be completed at 39℃ within 20 min, during which the results could be interpreted visually in real-time. The RF-RAA method had good specificity, no cross-reaction with common poultry pathogens, and it detected a minimum concentration of template of 2 copies/μL for IBV. Besides, its reproducibility was stable. A total of 144 clinical samples were tested by RF-RAA and real-time quantitative PCR (qPCR), 132 samples of which were positive and 12 samples were negative, and the coincidence rate of the two methods was 100 %. In conclusion, the developed RF-RAA detection method is rapid, specific, sensitive, reproducible, and convenient, which can be utilized for laboratory detection and clinical diagnosis of IBV.

Characterisation of the tracheal transcriptional response of chickens to chronic infection with Mycoplasma synoviae

Mycoplasma synoviae causes infectious synovitis and respiratory tract infections in chickens and is responsible for significant economic losses in the poultry industry. Effective attachment and colonisation of the trachea is critical for the persistence of the organism and progression of the disease it causes. The respiratory tract infection is usually sub-clinical, but concurrent infection with infectious bronchitis virus (IBV) is known to enhance the pathogenicity of M. synoviae. This study aimed to explore differentially expressed genes in the tracheal mucosa, and their functional categories, during chronic infection with M. synoviae, using a M. synoviae-IBV infection model. The transcriptional profiles of the trachea were assessed 2 weeks after infection using RNA sequencing. In chickens infected with M. synoviae or IBV, only 1 or 8 genes were differentially expressed compared to uninfected chickens, respectively. In contrast, the M. synoviae-IBV infected chickens had 621 upregulated and 206 downregulated genes compared to uninfected chickens. Upregulated genes and their functional categories were suggestive of uncontrolled lymphoid cell proliferation and an ongoing pro-inflammatory response. Genes associated with anti-inflammatory effects, pathogen removal, apoptosis, regulation of the immune response, airway homoeostasis, cell adhesion and tissue regeneration were downregulated. Overall, transcriptional changes in the trachea, 2 weeks after infection with M. synoviae and IBV, indicate immune dysregulation, robust inflammation and a lack of cytotoxic damage during chronic infection. This model provides insights into the pathogenesis of chronic infection with M. synoviae.

Deciphering infected cell types, hub gene networks and cell-cell communication in infectious bronchitis virus via single-cell RNA sequencing.

Infectious bronchitis virus (IBV) is a coronavirus that infects chickens, which exhibits a broad tropism for epithelial cells, infecting the tracheal mucosal epithelium, intestinal mucosal epithelium, and renal tubular epithelial cells. Utilizing single-cell RNA sequencing (scRNA-seq), we systematically examined cells in renal, bursal, and tracheal tissues following IBV infection and identified tissue-specific molecular markers expressed in distinct cell types. We evaluated the expression of viral RNA in diverse cellular populations and subsequently ascertained that distal tubules and collecting ducts within the kidney, bursal mucosal epithelial cells, and follicle-associated epithelial cells exhibit susceptibility to IBV infection through immunofluorescence. Furthermore, our findings revealed an upregulation in the transcription of proinflammatory cytokines IL18 and IL1B in renal macrophages as well as increased expression of apoptosis-related gene STAT in distal tubules and collecting duct cells upon IBV infection leading to renal damage. Cell-to-cell communication unveiled potential interactions between diverse cell types, as well as upregulated signaling pathways and key sender-receiver cell populations after IBV infection. Integrating single-cell data from all tissues, we applied weighted gene co-expression network analysis (WGCNA) to identify gene modules that are specifically expressed in different cell populations. Based on the WGCNA results, we identified seven immune-related gene modules and determined the differential expression pattern of module genes, as well as the hub genes within these modules. Our comprehensive data provides valuable insights into the pathogenesis of IBV as well as avian antiviral immunology.