ABSTRACT
Type 1 interferon (IFN-I) response is the first line of host defense against invading viruses. In the absence of definite mouse models, however, the role of IFN-I in SARS-CoV-2 infections remained to be perplexing. Here, we developed two mouse models, one with constitutively high IFN-I response (hACE2; Irgm1-/-) and the other with dampened IFN-I response (hACE2; Ifnar1-/-) to comprehend the role of IFN-I response during SARS-CoV-2 invasion. We found that hACE2; Irgm1-/- mice were resistant to lethal SARS-CoV-2 (including delta variant) infection with substantially reduced cytokine storm and immunopathology in the lungs and brain. In striking contrast, a severe SARS-CoV-2 infection along with immune cell infiltration, inflammatory response, and enhanced pathology was observed in the lungs of hACE2; Ifnar1-/- mice. Additionally, hACE2; Ifnar1-/- mice were highly susceptible to SARS-CoV-2 neuroinvasion in the brain accompanied by immune cell infiltration, microglia/astrocytes activation, cytokine response, and demyelination of neurons. The hACE2; Irgm1-/- Ifnar1-/- double knockout mice or hACE2; Irgm1-/- mice treated with STING or RIPK2 pharmacological inhibitors displayed loss of the protective phenotypes observed in hACE2; Irgm1-/- mice suggesting that heightened IFN-I response accounts for the observed immunity. Taken together, we explicitly demonstrate that IFN-I protects from lethal SARS-CoV-2 infection, and Irgm1 (IRGM) could be an excellent therapeutic target against COVID-19.
Subject(s)
Severe Acute Respiratory Syndrome , COVID-19 , Demyelinating DiseasesABSTRACT
Background The coronavirus disease 2019 (COVID-19) pandemic caused by severe acute respiratory syndrome corona virus 2 (SARS-CoV-2) is a major global health concern. This virus infects the upper respiratory tract and causes pneumonia-like symptoms. So far, few studies have shown alterations in nasopharyngeal (NP) microbial diversity, enrichment of opportunistic pathogens and their role in co-infections during respiratory infections. Therefore, we hypothesized that microbial diversity changes, with increase in the population of opportunistic pathogens, during SARS-CoV2 infection in the nasopharynx which may be involved in co-infection in COVID-19 patients. Methods The 16S rRNA variable regions, V1-V9, of NP samples of control and COVID-19 (symptomatic and asymptomatic) patients were sequenced using the Oxford Nanopore™ technology. Comprehensive bioinformatics analysis for determining alpha/beta diversities, non-metric multidimensional scaling, correlation studies, canonical correspondence analysis, linear discriminate analysis, and dysbiosis index were used to analyze the control and COVID-19-specific NP microbiomes. Results We observed significant dysbiosis in COVID-19 NP microbiome with increase in abundance of opportunistic pathogens at genus and species levels in asymptomatic/symptomatic patients. The significant abundance of Mycobacteria spp. and Mycoplasma spp. in symptomatic patients suggest their association and role in co-infections in COVID-19 patients. Furthermore, we found strong correlation of enrichment of Mycobacteria and Mycoplasma with the occurrences of chest pain and fever in symptomatic COVID-19 patients. Conclusion This is the first study from India to show the abundance of Mycobacteria and Mycoplasma opportunistic pathogens in non-hospitalized COVID-19 patients and their relationship with symptoms, indicating the possibility of co-infections.
Subject(s)
COVID-19ABSTRACT
The coronavirus disease 2019 (COVID-19) pandemic caused by severe acute respiratory syndrome corona virus 2 (SARS-CoV-2) is a major global health concern. This virus infects the upper respiratory tract and causes pneumonia-like symptoms. So far, few studies have shown that respiratory infections alter nasopharyngeal (NP) microbiome diversity and enrich opportunistic pathogens. In this study, we have sequenced the 16S rRNA variable regions, V1 through V9, extracted from NP samples of control and COVID-19 (symptomatic and asymptomatic) participants using the Oxford Nanopore technology. Comprehensive bioinformatics analysis investigating the alpha/beta diversities, non-metric multidimensional scaling, correlation studies, canonical correspondence analysis, linear discriminate analysis, and dysbiosis index analysis revealed control and COVID-19-specific NP microbiomes. We observed significant dysbiosis in COVID-19 NP microbiome with abundance of opportunistic pathogens such as Cutibacterium, Corynebacterium, Oerskovia, and Cellulomonas in asymptomatic patients, and of Streptomyces and Mycobacteriaceae family in symptomatic patients. Furthermore, we observed sharp rise in enrichment of opportunistic pathogens in symptomatic patients, with abundance of Mycobacteria and Mycoplasma, which strongly correlated with the occurrences of chest pain and fever. Our findings contribute novel insights regarding emergence of opportunistic pathogens in COVID-19 patients and their relationship with symptoms, suggesting their potential role in coinfections.