Project description:Coronaviruses express a repertoire of accessory proteins for evading host immune responses. A small internal (I) accessory gene overlaps with the nucleocapsid (N) gene in an alternative reading frame of viruses that belong to the genus Betacoronavirus. Previous studies reported that I proteins of SARS-CoV (9b), MERS-CoV (8b) and SARS-CoV-2 (9b) inhibit type I interferon (IFN-I) expression through distinct mechanisms and have different roles in pathogenesis. In contrast, the functions of the I proteins of human coronaviruses HCoV-HKU1 (7b) and HCoV-OC43 (8b) have not been previously reported. Although HCoV-HKU1 and HCoV-OC43 predominantly cause common cold in healthy adults (common cold CoVs, CCCoVs), susceptible individuals infected with these viruses can develop severe disease. The lack of robust reverse genetic systems, tissue culture and animal models limit the study of HCoV-HKU1 and HCoV-OC43 pathogenesis. Here, we examined how the heterologous expression of the HCoV-HKU1 and HCoV-OC43 I proteins impact pathogenesis in a mouse model of infection using a prototypic betacoronavirus. We inserted the I gene of HCoV-HKU1 (ORF 7b) and HCoV-OC43 (ORF 8b) independently into the genome of a neurotropic strain of mouse hepatitis virus (J2.2). J2.2 infection is well characterized with clearly defined immune responses which allows the study of these genes in the context of authentic coronavirus infection. We showed that ORF 7b of HCoV-HKU1, but not ORF 8b of HCoV-OC43, ameliorated MHV-J2.2 pathogenesis while ORF 8b of MERS-CoV exacerbated disease. The presence of HCoV-HKU1 ORF 7b decreased virus titers and cytokine expression while ORF 8b of MERS-CoV led to increased immune cell infiltration and virus titers in mice after J2.2 infection. Moreover, proteins expressed by ORF 7b of HCoV-HKU1 and ORF 8b of HCoV-OC43 showed different patterns of subcellular localization. Overall, our findings suggest that the I genes of different betacoronaviruses play unique roles in pathogenesis.
Project description:Protein expression in Staphylococcus sp. NIOSBK35 isolated from marine environment (mangrove sediments) to different concentrations of arsenic (III)
Project description:HKU1 is a human betacoronavirus and infects host cells via highly glycosylated spike protein (S). At present, N-glycosylation of HKU1 S has been reported, however, little is known about its O-glycosylation, which hinders an in-depth understanding of its biological functions. Herein, a comprehensive study of O-glycosylation of HKU1 S was carried out based on dual-functional histidine-bonded silica materials (HBS). The enrichment method for O-glycopeptides with HBS was developed and validated using standard proteins. The application of the developed method to HKU1 S1 subunit resulted in 61 novel O-glycosylation sites, among which 56% were predicted to be exposed on protein outer surface. Moreover, the O-linked glycans and their abundance on each HKU1 S1 site were also analyzed. The obtained O-glycosylation dataset would provide valuable insights for the understanding of the structure of HKU1 S.
