A Temperature-Sensitive Recombinant of Avian Coronavirus Infectious Bronchitis Virus Provides Complete Protection against Homologous Challenge

Avian coronavirus infectious bronchitis virus (IBV) is the etiological agent of infectious bronchitis, an acute highly contagious economically relevant respiratory disease of poultry. Vaccination is used to control IBV infections, with live-attenuated vaccines generated via serial passage of a virulent field isolate through embryonated hens' eggs. A fine balance must be achieved between attenuation and the retention of immunogenicity. The exact molecular mechanism of attenuation is unknown, and vaccines produced in this manner present a risk of reversion to virulence as few consensus level changes are acquired. Our previous research resulted in the generation of a recombinant IBV (rIBV) known as M41-R, based on a pathogenic strain M41-CK. M41-R was attenuated in vivo by two amino acid changes, Nsp10-Pro85Leu and Nsp14-Val393Leu; however, the mechanism of attenuation was not determined. Pro85 and Val393 were found to be conserved among not only IBV strains but members of the wider coronavirus family. This study demonstrates that the same changes are associated with a temperature-sensitive (ts) replication phenotype at 41°C in vitro, suggesting that the two phenotypes may be linked. Vaccination of specific-pathogen-free chickens with M41-R induced 100% protection against clinical disease, tracheal ciliary damage, and challenge virus replication following homologous challenge with virulent M41-CK. Temperature sensitivity has been used to rationally attenuate other viral pathogens, including influenza, and the identification of amino acid changes that impart both a ts and an attenuated phenotype may therefore offer an avenue for future coronavirus vaccine development. IMPORTANCE Infectious bronchitis virus is a pathogen of economic and welfare concern for the global poultry industry. Live-attenuated vaccines against are generated by serial passage of a virulent isolate in embryonated eggs until attenuation is achieved. The exact mechanisms of attenuation are unknown, and vaccines produced have a risk of reversion to virulence. Reverse genetics provides a method to generate vaccines that are rationally attenuated and are more stable with respect to back selection due to their clonal origin. Genetic populations resulting from molecular clones are more homogeneous and lack the presence of parental pathogenic viruses, which generation by multiple passage does not. In this study, we identified two amino acids that impart a temperature-sensitive replication phenotype. Immunogenicity is retained and vaccination results in 100% protection against homologous challenge. Temperature sensitivity, used for the development of vaccines against other viruses, presents a method for the development of coronavirus vaccines

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.publishedVersio

Identification of Amino Acids within Nonstructural Proteins 10 and 14 of the Avian Coronavirus Infectious Bronchitis Virus That Result in Attenuation In Vivo and In Ovo

The Gammacoronavirus infectious bronchitis virus (IBV) is a highly contagious global pathogen prevalent in all types of poultry flocks. IBV is responsible for economic losses and welfare issues in domestic poultry, resulting in a significant risk to food security. IBV vaccines are currently generated by serial passage of virulent IBV field isolates through embryonated hens' eggs. The different patterns of genomic variation accumulated during this process means that the exact mechanism of attenuation is unknown and presents a risk of reversion to virulence. Additionally, the passaging process adapts the virus to replicate in chicken embryos, increasing embryo lethality. Vaccines produced in this manner are therefore unsuitable for in ovo application. We have developed a reverse genetics system, based on the pathogenic IBV strain M41, to identify genes which can be targeted for rational attenuation. During the development of this reverse genetics system, we identified four amino acids, located in nonstructural proteins (nsps) 10, 14, 15, and 16, which resulted in attenuation both in vivo and in ovo. Further investigation highlighted a role of amino acid changes, Pro85Leu in nsp 10 and Val393Leu in nsp 14, in the attenuated in vivo phenotype observed. This study provides evidence that mutations in nsps offer a promising mechanism for the development of rationally attenuated live vaccines against IBV, which have the potential for in ovo application. IMPORTANCE The Gammacoronavirus infectious bronchitis virus (IBV) is the etiological agent of infectious bronchitis, an acute, highly contagious, economically important disease of poultry. Vaccination is achieved using a mixture of live attenuated vaccines for young chicks and inactivated vaccines as boosters for laying hens. Live attenuated vaccines are generated through serial passage in embryonated hens' eggs, an empirical process which achieves attenuation but retains immunogenicity. However, these vaccines have a risk of reversion to virulence, and they are lethal to the embryo. In this study, we identified amino acids in the replicase gene which attenuated IBV strain M41, both in vivo and in ovo. Stability assays indicate that the attenuating amino acids are stable and unlikely to revert. The data in this study provide evidence that specific modifications in the replicase gene offer a promising direction for IBV live attenuated vaccine development, with the potential for in ovo application

Manipulation of the unfolded protein response: A pharmacological strategy against coronavirus infection.

Coronavirus infection induces the unfolded protein response (UPR), a cellular signalling pathway composed of three branches, triggered by unfolded proteins in the endoplasmic reticulum (ER) due to high ER load. We have used RNA sequencing and ribosome profiling to investigate holistically the transcriptional and translational response to cellular infection by murine hepatitis virus (MHV), often used as a model for the Betacoronavirus genus to which the recently emerged SARS-CoV-2 also belongs. We found the UPR to be amongst the most significantly up-regulated pathways in response to MHV infection. To confirm and extend these observations, we show experimentally the induction of all three branches of the UPR in both MHV- and SARS-CoV-2-infected cells. Over-expression of the SARS-CoV-2 ORF8 or S proteins alone is itself sufficient to induce the UPR. Remarkably, pharmacological inhibition of the UPR greatly reduced the replication of both MHV and SARS-CoV-2, revealing the importance of this pathway for successful coronavirus replication. This was particularly striking when both IRE1α and ATF6 branches of the UPR were inhibited, reducing SARS-CoV-2 virion release (~1,000-fold). Together, these data highlight the UPR as a promising antiviral target to combat coronavirus infection

Commercial Immunoglobulin Products Contain Neutralizing Antibodies Against Severe Acute Respiratory Syndrome Coronavirus 2 Spike Protein

BACKGROUND: Patients with antibody deficiency respond poorly to COVID-19 vaccination and are at risk of severe or prolonged infection. They are given long-term immunoglobulin replacement therapy (IRT) prepared from healthy donor plasma to confer passive immunity against infection. Following widespread COVID-19 vaccination alongside natural exposure, we hypothesised that immunoglobulin preparations will now contain neutralising SARS-CoV-2 spike antibodies which confer protection against COVID-19 disease and may help to treat chronic infection. METHODS: We evaluated anti-SARS-CoV-2 spike antibody in a cohort of patients before and after immunoglobulin infusion. Neutralising capacity of patient samples and immunoglobulin products was assessed using in vitro pseudo-virus and live-virus neutralisation assays, the latter investigating multiple batches against current circulating omicron variants. We describe the clinical course of nine patients started on IRT during treatment of COVID-19. RESULTS: In 35 individuals with antibody deficiency established on IRT, median anti-spike antibody titre increased from 2123 to 10600 U/ml post-infusion, with corresponding increase in pseudo-virus neutralisation titres to levels comparable to healthy donors. Testing immunoglobulin products directly in the live-virus assay confirmed neutralisation, including of BQ1.1 and XBB variants, but with variation between immunoglobulin products and batches.Initiation of IRT alongside Remdesivir in patients with antibody deficiency and prolonged COVID-19 infection (median 189 days, maximum over 900 days with an ancestral viral strain) resulted in clearance of SARS-CoV-2 virus at a median of 20 days. CONCLUSIONS: Immunoglobulin preparations now contain neutralising anti-SARS-CoV-2 antibodies which are transmitted to patients and help to treat COVID-19 in individuals with failure of humoral immunity

Neutralising immunity to omicron sublineages BQ.1.1, XBB, and XBB.1.5 in healthy adults is boosted by bivalent BA.1-containing mRNA vaccination and previous Omicron infection

The global COVID-19 landscape is increasingly complex; emerging new variants rapidly cause waves of infection in people with variably induced immunity. Most individuals now have so-called hybrid immunity from both infection and vaccination. However, sequential infecting variants, induction of immunity, and subsequent waning are interlinked, and immune protection against new variants is unclear

PREVALENCE AND PHYLOGENETIC ANALYSIS OF BARTONELLA HENSELAE AND BARTONELLA CLARRIDGEIAE IN WESTERN SICILY

Cats from western Sicily were tested for Bartonella spp. by blood culture and PCR assays. B. henselae (18%) and B. clarridgeiae (3%) were detected in cats highly flea infested (P value= 0,031). 15% of the samples were identified as B..henselae belonging to genogroup II, whereas 3% was characterised as genogroup I, mainly associated with CSD in humans. Finally, we report the circulation of bacteria belonging to genus Bartonella in feline population of western Sicily, with high risk of infection to humans

Identification of Pantropic Canine Coronavirus in a Wolf (Canis lupus italicus) in Italy

We report a case in an Italian wolf (Canis lupus italicus) of pantropic canine coronavirus infection, which has previously been detected only in dogs. The wolf was coinfected by canine parvovirus type 2b and canine adenovirus type 2, which highlighted the crucial role of epidemiologic surveys in European wild carnivores

Full-genome sequence of pantropic canine coronavirus

Pantropic canine coronavirus (CCoV) was first detected in young dogs in Italy in 2005, but the complete genome sequence of this virus had not yet been determined. Here, we report the full-length genome sequence of the prototype strain CB/05, which showed that this virus is genetically similar to CCoV-IIa viruses

Full-length genome analysis of canine coronavirus type I

Canine coronavirus types I (CCoV-I) and II (CCoV-II) are usually responsible for mild enteritis in dogs. While the CCoV-II genome has been completely sequenced, to date there are no complete genomic sequence data available publicly for CCoV-I. Thus, the aim of the present study was to analyze the full-length genome of a CCoV-I prototype strain that had been recovered from a dog with diarrhea in Italy. CCoV-I strain 23/03 has a genome of 30,000 nucleotides, excluding the 3' poly(A) tail, displaying the typical Alphacoronavirus-1 organization and the highest genetic relatedness to CCoV-II. However, two distinct features were observed in the CCoV-I genome: (i) the presence of an additional ORF between the spike (S) protein gene and ORF3a; (ii) the diversity of the S protein, which is more closely related to that of feline coronavirus type I and presents a furin cleavage site. The present study may contribute to a better understanding of the Alphacoronavirus-1 evolutionary pattern and may be paradigmatic of how coronaviruses evolve through gene losses, acquisition and exchanges among different members