Deletion of the s2m RNA Structure in the Avian Coronavirus Infectious Bronchitis Virus and Human Astrovirus Results in Sequence Insertions.

Coronaviruses infect a wide variety of host species, resulting in a range of diseases in both humans and animals. The coronavirus genome consists of a large positive-sense single-stranded molecule of RNA containing many RNA structures. One structure, denoted s2m and consisting of 41 nucleotides, is located within the 3' untranslated region (3' UTR) and is shared between some coronavirus species, including infectious bronchitis virus (IBV), severe acute respiratory syndrome coronavirus (SARS-CoV), and SARS-CoV-2, as well as other pathogens, including human astrovirus. Using a reverse genetic system to generate recombinant viruses, we investigated the requirement of the s2m structure in the replication of IBV, a globally distributed economically important Gammacoronavirus that infects poultry causing respiratory disease. Deletion of three nucleotides predicted to destabilize the canonical structure of the s2m or the deletion of the nucleotides corresponding to s2m impacted viral replication in vitro. In vitro passaging of the recombinant IBV with the s2m sequence deleted resulted in a 36-nucleotide insertion in place of the deletion, which was identified to be composed of a duplication of flanking sequences. A similar result was observed following serial passage of human astrovirus with a deleted s2m sequence. RNA modeling indicated that deletion of the nucleotides corresponding to the s2m impacted other RNA structures present in the IBV 3' UTR. Our results indicated for both IBV and human astrovirus a preference for nucleotide occupation in the genome location corresponding to the s2m, which is independent of the specific s2m sequence. IMPORTANCE Coronaviruses infect many species, including humans and animals, with substantial effects on livestock, particularly with respect to poultry. The coronavirus RNA genome consists of structural elements involved in viral replication whose roles are poorly understood. We investigated the requirement of the RNA structural element s2m in the replication of the Gammacoronavirus infectious bronchitis virus, an economically important viral pathogen of poultry. Using reverse genetics to generate recombinant IBVs with either a disrupted or deleted s2m, we showed that the s2m is not required for viral replication in cell culture; however, replication is decreased in tracheal tissue, suggesting a role for the s2m in the natural host. Passaging of these viruses as well as human astrovirus lacking the s2m sequence demonstrated a preference for nucleotide occupation, independent of the s2m sequence. RNA modeling suggested deletion of the s2m may negatively impact other essential RNA structures.

MOLECULAR SIMILARLY BETWEEN INFECTIOUS BRONCHITIS VIRUSES AND COMMON VACCINES

Infectious bronchitis is an acute extremely infectious respiratory illness caused by the avian gamma-corona virus. Infection with infectious bronchitis virus predisposes the bird to subsequent bacterial infection, worsening the situation. Infection causes severe morbidity and variable mortality in broilers, as well as a significant decrease in layer production of eggs. Samples were collected from clinical cases submitted for necropsy at local veterinary clinics.This study was conducted to detect the molecular similarity in S1 gene sequence between field viruses and commonly used vaccines. In order to compare the sequences of field viruses with vaccinal viruses, two vaccines are chosen based on their popularity in veterinary clinics. These are MA5 strain and H120 strain. Molecular identification was done by using polymerase chain reaction (PCR) which was employed using primers target the S1 gene. Four positive field cases and two vaccine samples were sent to sequencing. The results of sequence alignment showed that vaccine viruses differ by more than 30% when compared to sequences of all the field viruses. The difference between genetic sequence leads to vaccine failure due to difference in the antigenic molecules on the spike protein of IBV © 2022, Revista Iberoamericana de Psicologia del Ejercicio y el Deporte.All Rights Reserved.

Genetic analysis of infectious bronchitis virus (IBV) in vaccinated poultry populations over a period of 10 years.

Infectious bronchitis virus (IBV) is an avian pathogen from the Coronavirus family causing major health issues in poultry flocks worldwide. Because of its negative impact on health, performance, and bird welfare, commercial poultry are routinely vaccinated by administering live attenuated virus. However, field strains are capable of rapid adaptation and may evade vaccine-induced immunity. We set out to describe dynamics within and between lineages and assess potential escape from vaccine-induced immunity. We investigated a large nucleotide sequence database of over 1700 partial sequences of the S1 spike protein gene collected from clinical samples of Dutch chickens submitted to the laboratory of Royal GD between 2011 and 2020. Relative frequencies of the two major lineages GI-13 (793B) and GI-19 (QX) did not change in the investigated period, but we found a succession of distinct GI-19 sublineages. Analysis of dN/dS ratio over all sequences demonstrated episodic diversifying selection acting on multiple sites, some of which overlap predicted N-glycosylation motifs. We assessed several measures that would indicate divergence from vaccine strains, both in the overall database and in the two major lineages. However, the frequency of vaccine-homologous lineages did not decrease, no increase in genetic variation with time was detected, and the sequences did not grow more divergent from vaccine sequences in the examined time window. Concluding, our results show sublineage turnover within the GI-19 lineage and we demonstrate episodic diversifying selection acting on the partial sequence, but we cannot confirm nor rule out escape from vaccine-induced immunity. RESEARCH HIGHLIGHTSSuccession of GI-19 IBV variants in broiler populations.IBV lineages overrepresented in either broiler, or layer production chickens.Ongoing episodic selection at the IBV S1 spike protein gene sequence.Several positively selected codons coincident with N-glycosylation motifs.

Guanylate-binding protein 1 restricts avian coronavirus infectious bronchitis virus-infected HD11 cells.

The Infectious Bronchitis Virus (IBV), a coronavirus, is a key avian pathogen that causes acute and highly infectious viral respiratory diseases. IBV is an enveloped, positive-sense RNA virus, and the host factors that restrict infection and replication of the virus remain poorly understood. Guanylate-binding protein 1 (GBP1), an interferon-gamma (IFN-γ)-inducible guanosine triphosphatase (GTPase), is a major player in host immunity and provides defense against viral replication. However, the role of chicken GBP1 (chGBP1) in the IBV-life cycle is not well understood. Therefore, this study aimed to reveal the potential role of IFN-γ-induced chGBP1 in mediating host anti-IBV infection responses. We identified the host restriction factor, chGBP1, in IBV-infected chicken macrophages HD11 cell lines. We showed that chGBP1 was upregulated by treatment with both IFN-γ and IBV in HD11 cells. chGBP1 inhibited IBV replication in a dose-dependent manner and enhanced IFN-γ anti-IBV activity. Importantly, the GTPase domain of chGBP1 played a pivotal role in its anti-IBV activity. Furthermore, chGBP1 interacts with IBV Nucleocapsids protein to degrade IBV-N protein through the autophagy pathway. Taken together, our results demonstrate a critical role of chGBP1 in anti-IBV in macrophages HD11 cells.

Synthesis of Novel 1,3,4-Oxadiazole-Derived α-Aminophosphonates/α-Aminophosphonic Acids and Evaluation of Their In Vitro Antiviral Activity against the Avian Coronavirus Infectious Bronchitis Virus.

An efficient and simple approach has been developed for the synthesis of eight dialkyl/aryl[(5-phenyl-1,3,4-oxadiazol-2-ylamino)(aryl)methyl]phosphonates through the Pudovik-type reaction of dialkyl/arylphosphite with imines, obtained from 5-phenyl-1,3,4-oxadiazol-2-amine and aromatic aldehydes, under microwave irradiation. Five of them were hydrolyzed to lead to the corresponding phosphonic acids. Selected synthesized compounds were screened for their in vitro antiviral activity against the avian bronchitis virus (IBV). In the MTT cytotoxicity assay, the dose-response curve showed that all test compounds were safe in the range concentration of 540-1599 µM. The direct contact of novel synthesized compounds with IBV showed that the diethyl[(5-phenyl-1,3,4-oxadiazol-2-ylamino)(4-trifluoromethoxyphenyl)methyl]phosphonate (5f) (at 33 µM) and the [(5-phenyl-1,3,4-oxadiazol-2-ylamino)(4-trifluoromethylphenyl)methyl] phosphonic acid (6a) (at 1.23 µM) strongly inhibited the IBV infectivity, indicating their high virucidal activity. However, virus titers from IBV-infected Vero cells remained unchanged in response to treatment with the lowest non-cytotoxic concentrations of synthesized compounds suggesting their incapacity to inhibit the virus replication inside the host cell. Lack of antiviral activity might presumably be ascribed to their polarity that hampers their diffusion across the lipophilic cytoplasmic membrane. Therefore, the interactions of 5f and 6a were analyzed against the main coronavirus protease, papain-like protease, and nucleocapsid protein by molecular docking methods. Nevertheless, the novel 1,3,4-oxadiazole-based α-aminophosphonic acids and α-amino-phosphonates hold potential for developing new hygienic virucidal products for domestic, chemical, and medical uses.

MOLECULAR SIMILARLY BETWEEN INFECTIOUS BRONCHITIS VIRUSES AND COMMON VACCINES

Infectious bronchitis is an acute extremely infectious respiratory illness caused by the avian gamma-corona virus. Infection with infectious bronchitis virus predisposes the bird to subsequent bacterial infection, worsening the situation. Infection causes severe morbidity and variable mortality in broilers, as well as a significant decrease in layer production of eggs. Samples were collected from clinical cases submitted for necropsy at local veterinary clinics.This study was conducted to detect the molecular similarity in S1 gene sequence between field viruses and commonly used vaccines. In order to compare the sequences of field viruses with vaccinal viruses, two vaccines are chosen based on their popularity in veterinary clinics. These are MA5 strain and H120 strain. Molecular identification was done by using polymerase chain reaction (PCR) which was employed using primers target the S1 gene. Four positive field cases and two vaccine samples were sent to sequencing. The results of sequence alignment showed that vaccine viruses differ by more than 30% when compared to sequences of all the field viruses. The difference between genetic sequence leads to vaccine failure due to difference in the antigenic molecules on the spike protein of IBV © 2022, Revista Iberoamericana de Psicologia del Ejercicio y el Deporte.All Rights Reserved.

Development of SYBR green RT-qPCR assay for titrating bivalent live infectious bronchitis vaccines.

Infectious bronchitis (IB) is a highly contagious viral disease of chickens caused by IB virus (IBV) that can cause substantial economic losses in the poultry industry. IBV variant infections have been continuously reported since the initial description in the 1930s. QX-like IBVs are the predominant circulating genotype globally. A homologous QX vaccine has superior protection efficacy compared with that of other available vaccines, and the combination of Massachusetts (Mass)-like and QX-like strains is being used to combat QX-like IBV infections. Inoculation of embryonated chicken eggs is the standard method for the titration of IBV, and the titer is expressed as 50% egg infectious dose (EID50). However, this method cannot effectively distinguish or quantify different genotypic strains in a mixture of different viruses, especially in the absence of neutralizing monoclonal antibodies. In this study, quantitative real-time PCR (RT-qPCR) was applied using specific primers for the QX- and Mass-like strains to quantitate IBV infection and for comparison with the conventional virus titration quantitative method. A strong positive correlation was observed between RT-qPCR cycle threshold values and the different EID50 concentrations. This method was further used to titrate bivalent IB vaccines, and the amount of individual genotype virus was determined based on specific primers. Thus, this RT-qPCR assay may be used as a highly specific, sensitive, and rapid alternative to the EID50 assay for titering IBVs.

A Multiplex Polymerase Chain Reaction for Differential Detection of Turkey Coronavirus from Chicken Infectious Bronchitis Virus and Bovine Coronavirus

A multiplex polymerase chain reaction (PCR) method for differential detection of turkey coronavirus (TCoV), infectious bronchitis virus (IBV), and bovine coronavirus (BCoV) is presented in this chapter. Primers are designed from the conserved or variable regions of nucleocapsid (N) or spike (S) protein genes of TCoV, IBV, and BCoV and used in the same PCR reaction. Reverse transcription followed by PCR reaction is used to amplify a portion of N or S gene of the corresponding coronaviruses. Two PCR products, a 356-bp band corresponding to N gene and a 727-bp band corresponding to S gene, are obtained for TCoV. In contrast, one PCR product of 356 bp corresponding to a fragment of N gene is obtained for IBV strains and one PCR product of 568 bp corresponding to a fragment of S gene is obtained for BCoV. Copyright © Springer Science+Business Media New York 2016.

An RT-PCR Assay for Detection of Infectious Bronchitis Coronavirus Serotypes

Avian infectious bronchitis virus (IBV), a chicken Gammacoronavirus, is a major poultry pathogen, and is probably endemic in all regions with intensive poultry production. Since IBV was first described in 1936, many serotypes and variants of IBV have been isolated worldwide. IBV isolates are capable of infecting a large range of epithelial surfaces of the chicken, involving the respiratory, renal, and reproductive systems;however, the clinical signs are usually not specific for differential diagnoses. Virus isolation is commonly used for diagnosis of IBV infection, which was achieved through passage of clinical materials via the allantoic route of embryos. Currently, more sensitive molecular approaches for the detection of avian pathogens have been developed, including reverse-transcriptase polymerase chain reaction (RT-PCR) and real-time RT-PCR, which are more suitable for use in diagnostic laboratories. In this chapter, we describe a one-step RT-PCR which can be used for detecting most of IBV serotypes in the IBV-infected allantoic fluid and has been used routinely in our laboratories for detection of IBVs. Copyright © Springer Science+Business Media New York 2016.

Reverse Genetics of Avian Coronavirus Infectious Bronchitis Virus

We have developed a reverse genetics system for the avian coronavirus infectious bronchitis virus (IBV) in which a full-length cDNA corresponding to the IBV genome is inserted into the vaccinia virus genome under the control of a T7 promoter sequence. Vaccinia virus as a vector for the full-length IBV cDNA has the advantage that modifications can be introduced into the IBV cDNA using homologous recombination, a method frequently used to insert and delete sequences from the vaccinia virus genome. Here, we describe the use of transient dominant selection as a method for introducing modifications into the IBV cDNA;that has been successfully used for the substitution of specific nucleotides, deletion of genomic regions, and the exchange of complete genes. Infectious recombinant IBVs are generated in situ following the transfection of vaccinia virus DNA, containing the modified IBV cDNA, into cells infected with a recombinant fowlpox virus expressing T7 DNA dependant RNA polymerase. Copyright © Springer Science+Business Media New York 2016.

Antibody-Capture Enzyme-Linked Immunosorbent Assay for Detection of Antibody to Turkey Coronavirus Using Infectious Bronchitis Virus or Recombinant Nucleocapsid Protein as Coating Antigen

Turkey coronavirus (TCoV) infection continues to threaten turkey industry. Because specific treatment and effective vaccination program are not available, rapid and cost-effective detection of antibodies to TCoV infection is an important control measure to monitor the disease status in the fields. Two antibody-capture enzyme-linked immunosorbent assay (ELISA) procedures for detection of antibodies to TCoV are outlined in this chapter. One ELISA method uses chicken infectious bronchitis coronavirus (IBV) as the coating antigen based on antigenic cross-reactivity between TCoV and IBV. The other method relies on a recombinant TCoV nucleocapsid protein. Both methods are useful for serological diagnosis of TCoV infection in the turkey flocks. Copyright © Springer Science+Business Media New York 2016.

Geographic distribution of IBV lineages

Infectious bronchitis virus (IBV) is a leading cause of economic losses within the poultry industry, affecting both meat-type birds and layers. The highly contagious viral disease caused by Avian coronavirus was first described in the 1930s and still remains a global problem for the poultry industry. Infection by Avian coronavirus causes respiratory disease, nephritis, decreased egg production depending on the viral pathotype and the age of the affected flocks. Live attenuated and inactivated vaccines are used to control the disease, but poor cross-protection between different serotypes complicates control efforts. IBV exists in a wide variety of genetically distinct types and new variants are identified relatively frequently. As the emergence of new IBV variants may impede the efficacy of the vaccines, monitoring the prevalence and genetic characteristics of IBV is of utmost importance. Currently, a phylogeny-based classification system defined by Valastro and coworkers is used for the classification of IBV strains. At present, IBV strains are divided into 8 genotypes (GI-GVIII) and 39 distinct lineages (GI-1 to GI-31, GII-1, GII-2, GIII-1, GIV-1, GV-1, GVI-1, GVII-1 and GVIII-1) and a huge number of unclassified inter-lineage recombinants. Most IBV lineages are confined to specific geographic regions, and some countries report the circulation of unique lineages. In contrast, the GI-1, GI-13, GI-16 and GI-19 lineages are widely distributed. The aim of this review is to summarize the most recent knowledge about the distribution of the genetic groups of Avian coronavirus.

Antiviral and Anti-SARS-CoV-2 Activity of Natural Chlorogenic Acid and Its Synthetic Derivatives

Since the dawn of time, several viral epidemics have swept the globe, among them the current COVID-19 outbreak. The ongoing emergence and propagation of novel viral illnesses have compelled researchers to seek new therapeutic approaches that can get beyond the drawbacks of antivirals that are available right now. Medicinal plants have historically offered treatments for a range of illnesses. These bioactive compounds serve as the foundation for many "modern" pharmaceuticals. One of the essential polyphenols in various medicinal plants is Chlorogenic acid (CA), an ester of caffeic and quinic acid. Extensive research has revealed that CA possesses anti-inflammatory, anticarcinogenic, and antioxidant properties. This review aims to briefly summarise CA and its derivative's antiviral properties on various human viral diseases and their ability to fight the current COVID-19 disease. This review summarises CA antiviral action on the following viruses: influenza A virus (H1N1/H3N2/H7N9), hepatitis C virus (HCV) and hepatitis B virus (HBV), human immunodeficiency virus (HIV), infectious bronchitis virus (IBV), porcine reproductive and respiratory syndrome virus (PRRSV), herpes simplex virus (HSV)-1, enterovirus 71 (Ent 71), adenoviruses (AdenV), and severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2). This review will open the way for developing and designing potentially effective and broad-spectrum CA-based antiviral medicines.

The conserved L1089 in the S2 subunit of avian infectious bronchitis virus determines viral kidney tropism by disrupting virus-cell fusion.

The virulence of avian gamma-coronavirus infectious bronchitis viruses (IBV) for the kidney has led to high mortality in dominant-genotype isolations, but the key sites of viral protein that determine kidney tropism are still not fully clear. In this study, the amino acid sequences of the S2 subunit of IBVs with opposing adaptivity to chicken embryonic kidney cells (CEKs) were aligned to identify putative sites associated with differences in viral adaptability. The S2 gene and the putative sites of the non-adapted CN strain were introduced into the CEKs-adapted SczyC30 strain to rescue seven mutants. Analysis of growth characteristics showed that the replacement of the entire S2 subunit and the L1089I substitution in the S2 subunit entirely abolished the proliferation of recombinant IBV in CEKs as well as in primary chicken oviduct epithelial cells. Pathogenicity assays also support the decisive role of this L1089 for viral nephrotropism, and this non-nephrotropic L1089I substitution significantly attenuates pathogenicity. Analysis of the putative cause of proliferation inhibition in CEKs suggests that the L1089I substitution affects neither virus attachment nor endocytosis, but instead fails to form double-membrane vesicles to initiate the viral replication and translation. Position 1089 of the IBV S2 subunit is conservative and predicted to lie in heptad repeat 2 domains. It is therefore reasonable to conclude that the L1089I substitution alters the nephrotropism of parent strain by affecting virus-cell fusion. These findings provide crucial insights into the adaptive mechanisms of IBV and have applications in the development of vaccines and drugs against IB.

A surveillance for avian coronavirus infectious bronchitis virus, infectious laryngotracheitis virus, avian metapneumovirus, and avian reovirus in poultry fllocks with respiratory signs in Turkiye

In this study, avian coronavirus infectious bronchitis virus (IBV), infectious laryngotracheitis virus (ILTV), avian metapneumovirus (AMPV), and avian reovirus (ARV) were evaluated in broiler and layer flocks. For this purpose, tracheal swabs from 48 broiler and 45 layer flocks with respiratory signs were inoculated SPF embryonated chicken eggs for virus isolation. The viruses were identified by real-time PCR. Results showed that the most common virus in both broiler and layer farms was IBV with incidence rates of 58.33% and 46.67%, respectively. ILTV, AMPV, and ARV incidences in the samples were found to be 22.22%, 13.33%, and 4.44% in layer flocks while 2.08%, 8.33%, and 20.83% in broilers, respectively. The numbers of IBV+AMPV and IBV+ARV coinfections were 5 (11.11%) and 1 (2.22%) in layers, whereas, 1 (2.08%) and 5 (10.42%) broilers, respectively. In addition, 2 broiler flocks (4.17%) had triple infection with IBV, AMPV, and ARV. ILTV was detected always alone from the samples of layer and broiler flocks. Sequencing of S1 gene of selected IBV TR/L45 and TR/B42 isolates showed similarities with IS/1494/06 (HM131453) at the rates of 98.98% and 99.69%, respectively, while TR/L37, TR/L38, and TR/L39 isolates were identical to 4/91 (KF377577) vaccine strain at the rates of 99.01%, 99.01%, and 98.76%, respectively. Sequencing analysis of the ICP4 and TK genes of ILTV isolates revealed that they were all field strains with low virulence. The present data represent actual information on the genotypes of IBV and ILTV circulating in poultry flocks in Turkiye.

Diversity of coronaviruses in wild and domestic birds in Vietnam

Objective: To investigate the genetic diversity of coronaviruses in wild and domestic birds in the bird park and live poultry markets of Ca Mau province in Vietnam in 2020. Methods: A total of 228 samples (121 from wild birds and 107 from poultry) were collected in the territory of Ca Mau province of Vietnam in 2020. The avian samples were tested for the presence of the four genera of coronaviruses using reverse transcription and nested PCR. Molecular genetic analysis using targeted NGS sequencing of RdRp gene was performed for 29 representative samples (12 samples from wild birds and 17 from poultry). Phylogenetic analysis was performed using the neighbour joininig method with 1000 bootstrap replications using MEGA X software. Results: Among wild birds, 21.5% samples were positive for the genetic material of coronaviruses and 38.3% samples were positive for coronaviruses among poultry. Genetic analysis of the partial sequence of RdRp gene from representative samples revealed that wild birds were carriers of gammacoronaviruses and deltacoronaviruses. Among poultry, three genotypes of infectious bronchitis virus (QX, Mass and Q1) were detected in chickens, with QX genotypes being predominant, and viruses of DCoV group were detected in domestic ducks. There was no detection of alphacoronaviruses or betacoronaviruses in the studied birds. Conclusions: Coronaviruses of genera Gammacoronavirus and Deltacoronavirus were detected in wild birds. A high percentage of infectious bronchitis virus was detected in poultry. Thus, there is a need for broader surveillance of coronaviruses in birds, which can be used for evaluation of diversity, evolution and distribution of coronaviruses in Vietnam. Continuous surveillance of coronaviruses circulation in wild and domestic animals is necessary for implementing strategic measures for poultry and domestic animal protection and for evaluation of possible risk of circulating coronaviruses to human health.

Detection and isolation of QX-like infectious bronchitis virus in Japan.

The antigenic variant QX-like infectious bronchitis virus (IBV) is endemic in several countries. In Japan, the QX-like genotype is classified as the JP-III genotype based on the partial S1 gene and as the GI-19 genotype based on the complete S1 gene. This study showed that QX-like IBVs and JP-III IBVs can be identified based on the amino acid polymorphism of the S1 glycoprotein. Furthermore, genetic analysis of several IBV field strains detected in commercial broiler farms across the Kyushu area in 2020 revealed Japanese QX-like IBVs, which are highly homologous to the QX-like IBVs recently detected in China and South Korea. Herein, QX-like IBV field strains were isolated for evaluating commercial vaccine efficacy in our future studies.

Antiviral Properties of Pennisetum purpureum Extract against Coronaviruses and Enteroviruses.

Many severe epidemics are caused by enteroviruses (EVs) and coronaviruses (CoVs), including feline coronavirus (FCoV) in cats, epidemic diarrhea disease virus (PEDV) in pigs, infectious bronchitis virus (IBV) in chickens, and EV71 in human. Vaccines and antiviral drugs are used to prevent and treat the infection of EVs and CoVs, but the effectiveness is affected due to rapidly changing RNA viruses. Many plant extracts have been proven to have antiviral properties despite the continuous mutations of viruses. Napier grass (Pennisetum purpureum) has high phenolic content and has been used as healthy food materials, livestock feed, biofuels, and more. This study tested the antiviral properties of P. purpureum extract against FCoV, PEDV, IBV, and EV71 by in vitro cytotoxicity assay, TCID50 virus infection assay, and chicken embryo infection assay. The findings showed that P. purpureum extract has the potential of being disinfectant to limit the spread of CoVs and EVs because the extract can inhibit the infection of EV71, FCoV, and PEDV in cells, and significantly reduce the severity of symptoms caused by IBV in chicken embryos.

Origin of New Lineages by Recombination and Mutation in Avian Infectious Bronchitis Virus from South America.

The gammacoronavirus avian infectious bronchitis virus (IBV) is a highly contagious respiratory pathogen of primary economic importance to the global poultry industry. Two IBV lineages (GI-11 and GI-16) have been widely circulating for decades in South America. GI-11 is endemic to South America, and the GI-16 is globally distributed. We obtained full-length IBV genomes from Argentine and Uruguayan farms using Illumina sequencing. Genomes of the GI-11 and GI-16 lineages from Argentina and Uruguay differ in part of the spike coding region. The remaining genome regions are similar to the Chinese and Italian strains of the GI-16 lineage that emerged in Asia or Europe in the 1970s. Our findings support that the indigenous GI-11 strains recombine extensively with the invasive GI-16 strains. During the recombination process, GI-11 acquired most of the sequences of the GI-16, retaining the original S1 sequence. GI-11 strains with recombinant genomes are circulating forms that underwent further local evolution. The current IBV scenario in South America includes the GI-16 lineage, recombinant GI-11 strains sharing high similarity with GI-16 outside S1, and Brazilian GI-11 strains with a divergent genomic background. There is also sporadic recombinant in the GI-11 and GI-16 lineages among vaccine and field strains. Our findings exemplified the ability of IBV to generate emergent lineage by using the S gene in different genomic backgrounds. This unique example of recombinational microevolution underscores the genomic plasticity of IBV in South America.

Apigenin inhibits infectious bronchitis virus replication in ovo

OBJECTIVE: Infectious bronchi-tis virus (IBV), for which no effective drugs are available, is among the most important causes of economic loss within the poultry industry. Apigenin is a flavonoid that can be isolated from plants. Apigenin has low toxicity with anti-viral activity. However, the effects of apigenin against IBV remain unclear. MATERIALS AND METHODS: Thus, here we investigate the anti-viral effect of apigenin on IBV using 10 day-old embryonated eggs by determining the virus titer by embryo infective doses50 (EID50/mL) and determining IBV genomes copy number (per mu L) of allantoic fluid. RESULTS: We found that apigenin protected embryonated eggs from IBV. Additionally, apigenin reduced the log titer of the IBV with a significant correlation of up to 9.4 times at 2 mu g/ egg. Also, apigenin appears to significantly re-duce IBV genomes copy number (per mu L) in the allantoic fluid. CONCLUSIONS: Apigenin may be a promising approach for the treatment of IBV, since it protects embryonated eggs from IBV in ovo and suppresses viral replication.