Analysis of the avian coronavirus spike protein reveals heterogeneity in the glycans present

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.

Respiratory disease complex due to mixed viral infections in chicken in Jordan

The global distribution of avian respiratory viruses highlights the need for effective surveillance programs and international collaboration to monitor viral circulation and implement timely control measures. In the current study, we aim to provide a comprehensive overview of avian respiratory viral infections in the poultry flocks in Jordan, focusing on the major viruses involved, their epidemiology, clinical manifestations, and evolution based on viroinformatics that will be helpful to improve the diagnostic methods, and control strategies including vaccines in the region. In this research, various poultry broiler groups in Jordan experiencing respiratory symptoms were tested for respiratory viral pathogens from January 2021 to February 2022. The mortality rates observed in the examined groups varied between 6% and 40%. The identified strains were authenticated using the RT-qPCR assay. Furthermore, they underwent in-depth characterisation through the sequencing of the complete spike (S1) gene for infectious bronchitis virus (IBV) and the haemagglutinin (HA) gene for avian influenza virus (AIV) subtype H9N2. Co-infection of IBV and AIV H9N2 viruses was detected through molecular analysis. The IBV strains showed affiliation with the variant groups GI-16 (3 strains) and GI-23 (9 strains) and exhibited numerous mutations. Meanwhile, H9N2 avian influenza viruses displayed various changes in amino acids within the HA gene, suggesting the influence of antibody-driven selection pressure. The phylogenetic analysis revealed that the H9N2 viruses identified in this investigation shared close genetic ties with EG3 (3 strains) and the Middle East group (ME1; 8 strains). These strains have been recently found in Jordan and nearby countries in the Middle East. Moreover, their HA genes exhibited similarities to viruses belonging to the G1-like lineage. In conclusion, avian respiratory viral infections remain a significant concern for the poultry industry, requiring constant vigilance and proactive measures to minimise their impact. Continued surveillance, robust diagnostic methods, effective vaccines, and international cooperation are essential components of a comprehensive approach to combat avian respiratory viral infections (AI, IBV, ND and ILT 'viruses) and safeguard avian health and global poultry production.

Simultaneous and rapid detection of avian respiratory diseases of small poultry using multiplex reverse transcription-Polymerase Chain Reaction assay

Major viral infections, such as Newcastle disease virus, infectious bronchitis virus, avian influenza virus, and infectious bursal disease virus, inflict significant injury to small poultry and tremendous economic damage to the poultry sector. This research aims to develop a multiplex reverse transcriptase polymerase chain reaction (m-RT-PCR) approach to simultaneously determine these important viral pathogens. The conserved segment of various viral genetic sequences was used to design and synthesize specific primers. Moreover, as positive controls, recombinant vectors were synthesized in this investigation. The d-optimal approach was used to improve PCR conditions in this investigation. Positive controls and clinical samples were used to assess the m-PCR assay's specificity, sensitivity, repeatability, and reproducibility. According to the sensitivity test findings, the m-PCR technique could generate the 8 target genes from viral genomes using 1 × 102. In addition, 8 viral pathogens were detected from the infected samples. The findings also suggest that live animal oral swabs were not significantly different from tissue sampling of a dead animal (P < 0.05), and this kit had a high sensitivity for analyzing both types of samples. The suggested m-PCR test may detect and evaluate viral infection in birds with excellent specificity, sensitivity, and throughput.

Genetic Analysis of the Complete S1 Gene in Japanese Infectious Bronchitis Virus Strains

The complete nucleotide sequence of the S1 glycoprotein gene of the Japanese infectious bronchitis virus (IBV) strains was determined and genetically analyzed. A total of 61 Japanese IBV strains were classified into seven genotypes, namely GI-1, 3, 7, 13, 18, 19, and GVI-1 using the classification scheme that was proposed by Valastro et al, with three exceptions. These genotypes practically corresponded to those defined in Japan, namely Mass, Gray, JP-II, 4/91, JP-I, JP-III, and JP-IV, which have been identified through their partial nucleotide sequences containing hypervariable regions 1 and 2. In addition, three exceptive strains were considered to be derived from recombination within the S1 gene of IBV strains G1-13 and GI-19. By analyzing the amino acid polymorphism of the S1 glycoprotein among Japanese genotypes, a diversity was observed based on the genotype-specific amino acid residue, the proteolytic cleavage motif at the S1/S2 cleavage site, and the position of the potential N-glycosylation sites.

Known Cellular and Receptor Interactions of Animal and Human Coronaviruses: A Review

This article aims to review all currently known interactions between animal and human coronaviruses and their cellular receptors. Over the past 20 years, three novel coronaviruses have emerged that have caused severe disease in humans, including SARS-CoV-2 (severe acute respiratory syndrome virus 2); therefore, a deeper understanding of coronavirus host-cell interactions is essential. Receptor-binding is the first stage in coronavirus entry prior to replication and can be altered by minor changes within the spike protein-the coronavirus surface glycoprotein responsible for the recognition of cell-surface receptors. The recognition of receptors by coronaviruses is also a major determinant in infection, tropism, and pathogenesis and acts as a key target for host-immune surveillance and other potential intervention strategies. We aim to highlight the need for a continued in-depth understanding of this subject area following on from the SARS-CoV-2 pandemic, with the possibility for more zoonotic transmission events. We also acknowledge the need for more targeted research towards glycan-coronavirus interactions as zoonotic spillover events from animals to humans, following an alteration in glycan-binding capability, have been well-documented for other viruses such as Influenza A.