Interference between avian corona and influenza viruses: The role of the epithelial architecture of the chicken trachea.

Respiratory viral infections are among the major causes of disease in poultry. While viral dual infections are known to occur, viral interference in chicken airways is mechanistically hardly understood. The effects of infectious bronchitis virus (IBV) infection on tissue morphology, sialic acid (sia) expression and susceptibility of the chicken trachea for superinfection with IBV or avian influenza virus (AIV) were studied.

Wild and domestic animals variably display Neu5Ac and Neu5Gc sialic acids.

Sialic acids are used as a receptor by several viruses and variations in the linkage type or C-5 modifications affect the binding properties. A species barrier for multiple viruses is present due to α2,3- or α2,6-linked sialic acids. The C-5 position of the sialic acid can be modified to form N-acetylneuraminic acid (Neu5Ac) or N-glycolylneuraminic acid (Neu5Gc), which acts as a determinant for host susceptibility for pathogens such as influenza A virus, rotavirus, and transmissible gastroenteritis coronavirus.

Influenza D binding properties vary amongst the two major virus clades and wildlife species.

The influenza D virus (IDV) uses a trimeric hemagglutinin-esterase fusion protein (HEF) for attachment to 9-O-acetylated sialic acid receptors on the cell surface of host species. So far research has revealed that farm animals such as cattle, domestic pigs, goats, sheep and horses contain the necessary receptors on the epithelial surface of the respiratory tract to accommodate binding of the IDV HEF protein of both worldwide clades D/Oklahoma (D/OK) and D/Oklahoma/660 (D/660). More recently, seroprevalence studies have identified IDV-seropositive wildlife such as wild boar, deer, dromedaries, and small ruminants.

Pathology and Pathogenesis of Eurasian Blackbirds () Naturally Infected with Usutu Virus.

The Usutu virus (USUV) is a mosquito-borne zoonotic flavivirus. Despite its continuous circulation in Europe, knowledge on the pathology, cellular and tissue tropism and pathogenetic potential of different circulating viral lineages is still fragmentary. Here, macroscopic and microscopic evaluations are performed in association with the study of cell and tissue tropism and comparison of lesion severity of two circulating virus lineages (Europe 3; Africa 3) in 160 Eurasian blackbirds (Turdus merula) in the Netherlands.

The contribution of the immune response to enhanced colibacillosis upon preceding viral respiratory infection in broiler chicken in a dual infection model.

Colibacillosis in chickens caused by avian pathogenic Escherichia coli (APEC) is known to be aggravated by preceding infections with infectious bronchitis virus (IBV), Newcastle disease virus (NDV) and avian metapneumovirus (aMPV). The mechanism behind these virus-induced predispositions for secondary bacterial infections is poorly understood. Here we set out to investigate the immunopathogenesis of enhanced respiratory colibacillosis after preceding infections with these three viruses.

Tissue Microarrays to Visualize Influenza D Attachment to Host Receptors in the Respiratory Tract of Farm Animals.

The trimeric hemagglutinin-esterase fusion protein (HEF) of influenza D virus (IDV) binds 9-O-acetylated sialic acid receptors, which are expressed in various host species. While cattle are the main reservoir for IDV, the viral genome has also been detected in domestic pigs. In addition, antibodies against IDV have been detected in other farm animals such as sheep, goats, and horses, and even in farmers working with IDV positive animals.

N-glycosylation of infectious bronchitis virus M41 spike determines receptor specificity.

Infection of chicken coronavirus infectious bronchitis virus (IBV) is initiated by binding of the viral heavily N-glycosylated attachment protein spike to the alpha-2,3-linked sialic acid receptor Neu5Ac. Previously, we have shown that N-glycosylation of recombinantly expressed receptor binding domain (RBD) of the spike of IBV-M41 is of critical importance for binding to chicken trachea tissue. Here we investigated the role of N-glycosylation of the RBD on receptor specificity and virus replication in the context of the virus particle.

The Microbiota Contributes to the Control of Highly Pathogenic H5N9 Influenza Virus Replication in Ducks.

Ducks usually show little or no clinical signs following highly pathogenic avian influenza virus infection. In order to analyze whether the microbiota could contribute to the control of influenza virus replication in ducks, we used a broad-spectrum oral antibiotic treatment to deplete the microbiota before infection with a highly pathogenic H5N9 avian influenza virus. Antibiotic-treated ducks and nontreated control ducks did not show any clinical signs following H5N9 virus infection.

miRNA repertoire and host immune factor regulation upon avian coronavirus infection in eggs.

Avian infectious bronchitis virus (IBV) is a coronavirus with great economic impact on the poultry industry, causing an acute and highly contagious disease in chickens that primarily affects the respiratory and reproductive systems. The cellular regulation of IBV pathogenesis and the host immune responses involved remain to be fully elucidated. MicroRNAs (miRNAs) have emerged as a class of crucial regulators of numerous cellular processes, including responses to viral infections.

Attenuated live infectious bronchitis virus QX vaccine disseminates slowly to target organs distant from the site of inoculation.

Infectious bronchitis (IB) is a highly contagious respiratory disease of poultry, caused by the avian coronavirus infectious bronchitis virus (IBV). Currently, one of the most relevant genotypes circulating worldwide is IBV-QX (GI-19), for which vaccines have been developed by passaging virulent QX strains in embryonated chicken eggs. Here we explored the attenuated phenotype of a commercially available QX live vaccine, IB Primo QX, in specific pathogens free broilers.

Three Amino Acid Changes in Avian Coronavirus Spike Protein Allow Binding to Kidney Tissue.

Infectious bronchitis virus (IBV) infects ciliated epithelial cells in the chicken respiratory tract. While some IBV strains replicate locally, others can disseminate to various organs, including the kidney. Here, we elucidate the determinants for kidney tropism by studying interactions between the receptor-binding domain (RBD) of the viral attachment protein spike from two IBV strains with different tropisms.

N-Glycolylneuraminic Acid as a Receptor for Influenza A Viruses.

A species barrier for the influenza A virus is the differential expression of sialic acid, which can either be α2,3-linked for avians or α2,6-linked for human viruses. The influenza A virus hosts also express other species-specific sialic acid derivatives. One major modification at C-5 is N-glycolyl (NeuGc), instead of N-acetyl (NeuAc).

Glycosylation of the viral attachment protein of avian coronavirus is essential for host cell and receptor binding.

Avian coronaviruses, including infectious bronchitis virus (IBV), are important respiratory pathogens of poultry. The heavily glycosylated IBV spike protein is responsible for binding to host tissues. Glycosylation sites in the spike protein are highly conserved across viral genotypes, suggesting an important role for this modification in the virus life cycle.

Guinea Fowl Coronavirus Diversity Has Phenotypic Consequences for Glycan and Tissue Binding.

Guinea fowl coronavirus (GfCoV) causes fulminating enteritis that can result in a daily death rate of 20% in guinea fowl flocks. Here, we studied GfCoV diversity and evaluated its phenotypic consequences. Over the period of 2014 to 2016, affected guinea fowl flocks were sampled in France, and avian coronavirus presence was confirmed by PCR on intestinal content and immunohistochemistry of intestinal tissue.

Fluorescent Trimeric Hemagglutinins Reveal Multivalent Receptor Binding Properties.

Influenza A virus carries hundreds of trimeric hemagglutinin (HA) proteins on its viral envelope that interact with various sialylated glycans on a host cell. This interaction represents a multivalent binding event that is present in all the current receptor binding assays, including those employing viruses or precomplexed HA trimers. To study the nature of such multivalent binding events, we fused a superfolder green fluorescent protein (sfGFP) to the C-terminus of trimeric HA to allow for direct visualization of HA-receptor interactions without the need for additional fluorescent antibodies.

Transmission Kinetics and histopathology induced by European Turkey Coronavirus during experimental infection of specific pathogen free turkeys.

Numerous viruses, mostly in mixed infections, have been associated worldwide with poult enteritis complex (PEC). In 2008 a coronavirus (Fr-TCoV 080385d) was isolated in France from turkey poults exhibiting clinical signs compatible with this syndrome. In the present study, the median infectious dose (ID ) transmission kinetics and pathogenicity of Fr-TCoV were investigated in 10-day-old SPF turkeys.

Ranavirus genotypes in the Netherlands and their potential association with virulence in water frogs (Pelophylax spp.).

Ranaviruses are pathogenic viruses for poikilothermic vertebrates worldwide. The identification of a common midwife toad virus (CMTV) associated with massive die-offs in water frogs (Pelophylax spp.) in the Netherlands has increased awareness for emerging viruses in amphibians in the country.

Enhanced Human-Type Receptor Binding by Ferret-Transmissible H5N1 with a K193T Mutation.

All human influenza pandemics have originated from avian influenza viruses. Although multiple changes are needed for an avian virus to be able to transmit between humans, binding to human-type receptors is essential. Several research groups have reported mutations in H5N1 viruses that exhibit specificity for human-type receptors and promote respiratory droplet transmission between ferrets.

Recombinant live attenuated avian coronavirus vaccines with deletions in the accessory genes 3ab and/or 5ab protect against infectious bronchitis in chickens.

Avian coronavirus infectious bronchitis virus (IBV) is a respiratory pathogen of chickens, causing severe economic losses in poultry industry worldwide. Live attenuated viruses are widely used in both the broiler and layer industry because of their efficacy and ability to be mass applied. Recently, we established a novel reverse genetics system based on targeted RNA recombination to manipulate the genome of IBV strain H52.

A single mutation in Taiwanese H6N1 influenza hemagglutinin switches binding to human-type receptors.

In June 2013, the first case of human infection with an avian H6N1 virus was reported in a Taiwanese woman. Although this was a single non-fatal case, the virus continues to circulate in Taiwanese poultry. As with any emerging avian virus that infects humans, there is concern that acquisition of human-type receptor specificity could enable transmission in the human population.

Chicken mannose binding lectin has antiviral activity towards infectious bronchitis virus.

Mannose binding lectin (MBL) is a collagenous C-type lectin, which plays an important role in innate immunity. It can bind to carbohydrates on the surface of a wide range of pathogens, including viruses. Here we studied the antiviral effect of recombinant chicken (rc)MBL against Infectious Bronchitis Virus (IBV), a highly contagious coronavirus of chicken.

Three mutations switch H7N9 influenza to human-type receptor specificity.

The avian H7N9 influenza outbreak in 2013 resulted from an unprecedented incidence of influenza transmission to humans from infected poultry. The majority of human H7N9 isolates contained a hemagglutinin (HA) mutation (Q226L) that has previously been associated with a switch in receptor specificity from avian-type (NeuAcα2-3Gal) to human-type (NeuAcα2-6Gal), as documented for the avian progenitors of the 1957 (H2N2) and 1968 (H3N2) human influenza pandemic viruses. While this raised concern that the H7N9 virus was adapting to humans, the mutation was not sufficient to switch the receptor specificity of H7N9, and has not resulted in sustained transmission in humans.

A reverse genetics system for avian coronavirus infectious bronchitis virus based on targeted RNA recombination.

Background: Avian coronavirus infectious bronchitis virus (IBV) is a respiratory pathogen of chickens that causes severe economic losses in the poultry industry worldwide. Major advances in the study of the molecular biology of IBV have resulted from the development of reverse genetics systems for the highly attenuated, cell culture-adapted, IBV strain Beaudette. However, most IBV strains, amongst them virulent field isolates, can only be propagated in embryonated chicken eggs, and not in continuous cell lines.

The 150-Loop Restricts the Host Specificity of Human H10N8 Influenza Virus.

Adaptation of influenza A viruses to new hosts are rare events but are the basis for emergence of new influenza pandemics in the human population. Thus, understanding the processes involved in such events is critical for anticipating potential pandemic threats. In 2013, the first case of human infection by an avian H10N8 virus was reported, yet the H10 hemagglutinin (HA) maintains avian receptor specificity.

A novel cetacean adenovirus in stranded harbour porpoises from the North Sea: detection and molecular characterization.

Harbour porpoises (Phocoena phocoena) are the most prevalent cetaceans in the North Sea. The fecal viral flora of 21 harbour porpoises stranded along the Dutch coastline was analyzed by a metagenomics approach. Sequences of a novel cetacean mastadenovirus, designated harbour porpoise adenovirus 1 (HpAdV-1), were detected.