Samantha Sives

Infectious bronchitis virus (IBV), a Gammacoronavirus , causes the economically damaging disease of poultry, infectious bronchitis. Development of IBV live attenuated vaccines (LAVs) is dependent on the supply of embryonated hens’ eggs and attenuation through serial passaging, upwards of 80 times. Vaccine development needs to keep pace with IBV evolution; an issue compounded as cross protection between individual IBV serotypes is unpredictable and often limited. Rational attenuation alongside the ability to propagate LAVs in cell culture offers significant advantages in terms of adaptability, cost, and speed. Most field IBV strains exhibit restricted in vitro tropism, being unable to replicate in primary or continuous cells without serial passage and adaptation. Beaudette, an attenuated IBV strain, is capable of replication in Vero cells, an ability conferred by the spike (S) glycoprotein. In this study, utilizing a recombinant IBV based on the nephropathogenic IBV strain D388, in which the S sequence is replaced with the equivalent sequence derived from Beaudette, we determine that the Beaudette spike can confer the ability to replicate in Vero cells and Beaudette’s associated attenuated in vivo phenotype to a distantly related IBV strain. Assessment of infectious progeny and viral RNA in vivo suggests that attenuation was conferred by a tissue tropism-independent molecular mechanism. Analysis of innate immune responses revealed a lower intensity and less inflammatory profile. Our findings support the use of the Beaudette S protein as an avenue for the development of rationally attenuated, cell culture-propagated rIBV vaccines and identify the S protein as a contributor to nephropathogenicity. IMPORTANCE: Infectious bronchitis virus (IBV), a Gammacoronavirus of chickens, causes significant economic losses worldwide. Current live attenuated vaccines (LAVs) are generated through extensive serial passage of virulent IBV strains in specific-pathogen-free (SPF) embryonated hen’s eggs, upwards of 80 passages. This process is slow, dependent on the availability of SPF embryonated eggs, and the molecular basis of attenuation remains poorly understood. Development of rationally attenuated, cell-culture-based IBV vaccines would enable more rapid responses to emerging viral variants/strains. Using a recombinant IBV, we demonstrated the spike glycoprotein from the attenuated IBV strain Beaudette can confer attenuation and the ability to replicate in Vero cells to a distantly related virulent IBV strain. Attenuation was not linked to changes in tissue tropism but was associated with altered host responses. Our research provides new insights into IBV pathogenesis and presents an avenue for rational attenuation that can be exploited for future development of cell-based IBV vaccines.

The avian coronavirus, infectious bronchitis virus (IBV), is an economically important infectious disease affecting chickens, with a diverse range of serotypes found globally. The major surface protein, spike (S), has high diversity between serotypes, and amino acid differences in the S1 sub-unit are thought to be responsible for poor cross-protection afforded by vaccination. Here, we attempt to address this, by using epitope mapping technology to identify shared and serotype-specific immunogenic epitopes of the S glycoprotein of three major circulating strains of IBV, M41, QX, and 4/91, via CLIPS peptide arrays based on peptides from the S1 sub-units. The arrays were screened with sera from chickens immunised with recombinant IBV, based on Beau-R backbone expressing heterologous S, generated in two independent vaccination/challenge trials. The screening of sera from rIBV vaccination experiments led to the identification of 52 immunogenic epitopes on the S1 of M41, QX, and 4/91. The epitopes were assigned into six overlapping epitope binding regions. Based on accessibility and location in the hypervariable regions of S, three sequences, ²⁵YVYYYQSAFRPPNGWHLQGGAYAVVNSTN⁵⁴, ⁶⁷TVGVIKDVYNQSVASI⁸², and ⁸³AMTVPPAGMSWSVS⁹⁶, were selected for further investigation, and synthetic peptide mimics were recognised by polyclonal sera. These epitopes may have the potential to contribute towards a broader cross-protective IBV vaccine.

Throughout the global coronavirus pandemic, we have seen an unprecedented volume of COVID-19 researchpublications. This vast body of evidence continues to grow, making it difficult for research users to keep up with the pace of evolving research findings. To enable the synthesis of this evidence for timely use by researchers, policymakers, and other stakeholders, we developed an automated workflow to collect, categorise, and visualise the evidence from primary COVID-19 research studies. We trained a crowd of volunteer reviewers to annotate studies by relevance to COVID-19, study objectives, and methodological approaches. Using these human decisions, we are training machine learning classifiers and applying text-mining tools to continually categorise the findings and evaluate the quality of COVID-19 evidence.

Gammacoronavirus infectious bronchitis virus (IBV) causes an economically important respiratory disease of poultry. Protective immunity is associated with the major structural protein, spike (S) glycoprotein, which induces neutralising antibodies and defines the serotype. Cross-protective immunity between serotypes is limited and can be difficult to predict. In this study, the ability of two recombinant IBV vaccine candidates, BeauR-M41(S) and BeauR-4/91(S), to induce cross-protection against a third serotype, QX, was assessed. Both rIBVs are genetically based on the Beaudette genome with only the S gene derived from either M41 or 4/91, two unrelated serotypes. The use of these rIBVs allowed for the assessment of the potential of M41 and 4/91 S glycoproteins to induce cross-protective immunity against a heterologous QX challenge. The impact of the order of vaccination was also assessed. Homologous primary and secondary vaccination with BeauR-M41(S) or BeauR-4/91(S) resulted in a significant reduction of infectious QX load in the trachea at four days post-challenge, whereas heterologous primary and secondary vaccination with BeauR-M41(S) and BeauR-4/91(S) reduced viral RNA load in the conjunctiva-associated lymphoid tissue (CALT). Both homologous and heterologous vaccination regimes reduced clinical signs and birds recovered more rapidly as compared with an unvaccinated/challenge control group. Despite both rIBV BeauR-M41(S) and BeauR-4/91(S) displaying limited replication in vivo, serum titres in these vaccinated groups were higher as compared with the unvaccinated/challenge control group. This suggests that vaccination with rIBV primed the birds for a boosted humoral response to heterologous QX challenge. Collectively, vaccination with the rIBV elicited limited protection against challenge, with failure to protect against tracheal ciliostasis, clinical manifestations, and viral replication. The use of a less attenuated recombinant vector that replicates throughout the respiratory tract could be required to elicit a stronger and prolonged protective immune response.

Infectious bronchitis virus causes an acute, highly contagious respiratory disease, responsible for significant economic losses to the poultry industry. Amino acid differences in the surface protein, spike (S), in particular the S1 subunit, have been associated with poor cross-protection. Available vaccines give poor cross-protection and rationally designed live attenuated vaccines, based on apathogenic BeauR, could address these. Here, to determine the role of S1 in protection, a series of homologous vaccination trials with rIBVs were conducted. Single vaccinations with chimeric rIBVs induced virus-specific partial protective immunity, characterized by reduction in viral load and serum antibody titers. However, BeauR-M41(S) was the only vaccination to improve the level of protection against clinical signs and the loss of tracheal ciliary activity. Growth characteristics show that all of the rIBVs replicatedin vitroto similar levels. Booster vaccinations and an rIBV with improvedin vivoreplication may improve the levels of protection.

Summary: Infections with parasitic nematodes are of significant welfare and economic importance worldwide, and because of the emergence of anthelmintic resistance, this has lead to alternative methods of parasite control being required. Vaccination offers a feasible alternative control, and the majority of research has focused on the production of recombinant versions of native antigens previously identified as protective in vaccinated animals. Attempts at the production of protective recombinant subunit vaccines have been hindered, however, as these antigens have invariably failed to replicate the same level of protective immune response as seen with the native versions. It has been proposed that these failures are owing to the fact that the recombinant proteins do not contain the appropriate post‐translational modifications to retain the protective capacity of the native molecules. In this review, we discuss a novel approach to vaccine antigen identification through the application of random peptide phage‐display libraries and their use to identify peptide sequences that potentially mimic the structure(s) of antigenic epitopes. This area of research is still relatively novel with respect to parasites, and the current state of the art will be discussed here.