IDENTIFICATION OF GENES INVOLVED IN THE ANTIVIRAL RESPONSE THROUGH GENETIC SCREENS IN DROSOPHILA

Innate immunity is essential for the host to defend against invading pathogens, such as viruses and bacteria. To identify novel genes or molecules that are involved in innate immunity, we carried out two genetic screens in Drosophila. From a forward screen of flies mutagenized with Ethyl methane sulfonate (EMS), four mutants with increased susceptibility to Drosophila X virus (DXV) were found. In this study, we focused on the rogue mutant and identified a novel antiviral gene rogue. The rogue mutant is highly susceptible to DXV infection and is unable to control viral replication during infection. The expression of rogue in either the hemocytes or the fat body is required for flies to control viral accumulation and to survive a viral infection. At an early stage of infection, rogue is induced and the amount of Rogue protein that locates to the nucleus increases. In addition, we confirm that the Rogue protein interacts with the polyA binding protein (PABP), and we propose that rogue restricts viral replication via translation regulation in Drosophila. The rogue mutant also has a phagosome maturation defect, which may contribute to its susceptibility to Staphylococcus aureus infection. RNAi knockdown of rogue in the fat body or the hemocytes in wild type flies results in high bacterial susceptibility. Introducing the rogue transgene in the hemocytes of the rogue mutant can rescue the mutant survival to both DXV and S. aureus. Together, our results demonstrate that rogue plays a critical role in defending against DXV and S. aureus infections. We performed another genetic screen on wild derived inbred flies from the Drosophila Genetic Reference Panel (DGRP). From a genome wide association study (GWAS) in these flies, we found four single nucleotide polymorphisms (SNPs) associated with susceptibility of flies to DXV. One allele contributed most to the susceptibility is located in the intron of Socs36E, a negative regulator of the JAK-STAT pathway, implicating that the JAK-STAT pathway plays a role in the immune responses against DXV. Our study also shows that natural genetic variation can be used as a tool for identifying novel genes or pathways involved in antiviral immunity

Systemic and Lower Respiratory Tract Immunity to SARS-CoV-2 Omicron and Variants in Pediatric Severe COVID-19 and Mis-C

Mucosal immunity plays an important role in the control of viral respiratory infections like SARS-CoV-2. While systemic immune responses against the SARS-2-CoV-2 have been studied in children, there is no information on mucosal antibody response, especially in the lower respiratory tract of children coronavirus disease 2019 (COVID-19) and post-infectious multisystem inflammatory syndrome in children (MIS-C) against emerging SARS-CoV-2 variants. Therefore, we evaluated neutralizing antibody responses in paired plasma and endotracheal aspirates of pediatric severe, acute COVID-19 or MIS-C patients against SARS-CoV-2 WA1/2020, as well as against variants of concern (VOCs). Neutralizing antibody responses against the SARS-CoV-2 WA1/2020 strain in pediatric plasma were 2-fold or 35-fold higher compared with the matched endotracheal aspirate in COVID-19 or MIS-C patients, respectively. In contrast to plasma, neutralizing antibody responses against the VOCs and variants of interest (VOIs) in endotracheal aspirates were lower, with only one endotracheal aspirate demonstrating neutralizing titers against the Iota, Kappa, Beta, Gamma, and Omicron variants. In conclusion, our findings suggest that children and adolescents with severe COVID-19 or MIS-C have weak mucosal neutralizing antibodies in the trachea against circulating SARS-CoV-2 Omicron and other VOCs, which may have implications for recovery and for re-infection with emerging SARS-CoV-2 variants

A broadly cross-reactive antibody neutralizes and protects against sarbecovirus challenge in mice

Severe acute respiratory syndrome coronaviruses 1 (SARS-CoV) and 2 (SARS-CoV-2), including SARS-CoV-2 variants of concern, can cause deadly infections. The mortality associated with sarbecovirus infection underscores the importance of developing broadly effective countermeasures against them, which could be key in the prevention and mitigation of current and future zoonotic events. Here, we demonstrate the neutralization of SARS-CoV, bat coronaviruses WIV-1, RsSHC014, and SARS-CoV-2 variants D614G, B.1.1.7, B.1.351, P.1, B.1.429, B.1.526, B.1.617.1, and B.1.617.2 by a receptor-binding domain (RBD)-specific human antibody, DH1047. Prophylactic and therapeutic treatment with DH1047 was protective against SARS-CoV, WIV-1, RsSHC014, and SARS-CoV-2 B.1.351 infection in mice. Binding and structural analysis showed high affinity binding of DH1047 to an epitope that is highly conserved among sarbecoviruses. Thus, DH1047 is a broadly protective antibody that can prevent infection and mitigate outbreaks caused by SARS-related strains and SARS-CoV-2 variants. Our results also suggest that the conserved RBD epitope bound by DH1047 is a rational target for a universal sarbecovirus vaccin

Protective antigenic sites identified in respiratory syncytial virus fusion protein reveals importance of p27 domain

Abstract Respiratory syncytial virus (RSV) vaccines primarily focused on surface fusion (F) protein are under development. Therefore, to identify RSV‐F protective epitopes, we evaluated 14 antigenic sites recognized following primary human RSV infection. BALB/c mice were vaccinated with F peptides, F proteins, or RSV‐A2, followed by rA2‐Line19F challenge. F peptides generated binding antibodies with minimal in vitro neutralization titers. However, several F peptides (including Site II) reduced lung viral loads and lung pathology scores in animals, suggesting partial protection from RSV disease. Interestingly, animals vaccinated with peptides (aa 101–121 and 110–136) spanning the F‐p27 sequence, which is only present in unprocessed F0 protein, showed control of viral loads with significantly reduced pathology compared with mock‐vaccinated controls. Furthermore, we observed F‐p27 expression on the surface of RSV‐infected cells as well as lungs from RSV‐infected mice. The anti‐p27 antibodies demonstrated antibody‐dependent cellular cytotoxicity (ADCC) of RSV‐infected A549 cells. These findings suggest that p27‐mediated immune response may play a role in control of RSV disease in vivo, and F‐p27 should be considered for inclusion in an effective RSV vaccine

Antibody affinity maturation and plasma IgA associate with clinical outcome in hospitalized COVID-19 patients

SARS-CoV2 infection has been linked to a wide range of clinical severities and the immunopathology is still under intense scrutiny. Here, the authors uncover an association of antibody affinity maturation and plasma IgA levels with clinical outcome in patients with COVID-19 disease

Systemic and Lower Respiratory Tract Immunity to SARS-CoV-2 Omicron and Variants in Pediatric Severe COVID-19 and Mis-C

Mucosal immunity plays an important role in the control of viral respiratory infections like SARS-CoV-2. While systemic immune responses against the SARS-2-CoV-2 have been studied in children, there is no information on mucosal antibody response, especially in the lower respiratory tract of children coronavirus disease 2019 (COVID-19) and post-infectious multisystem inflammatory syndrome in children (MIS-C) against emerging SARS-CoV-2 variants. Therefore, we evaluated neutralizing antibody responses in paired plasma and endotracheal aspirates of pediatric severe, acute COVID-19 or MIS-C patients against SARS-CoV-2 WA1/2020, as well as against variants of concern (VOCs). Neutralizing antibody responses against the SARS-CoV-2 WA1/2020 strain in pediatric plasma were 2-fold or 35-fold higher compared with the matched endotracheal aspirate in COVID-19 or MIS-C patients, respectively. In contrast to plasma, neutralizing antibody responses against the VOCs and variants of interest (VOIs) in endotracheal aspirates were lower, with only one endotracheal aspirate demonstrating neutralizing titers against the Iota, Kappa, Beta, Gamma, and Omicron variants. In conclusion, our findings suggest that children and adolescents with severe COVID-19 or MIS-C have weak mucosal neutralizing antibodies in the trachea against circulating SARS-CoV-2 Omicron and other VOCs, which may have implications for recovery and for re-infection with emerging SARS-CoV-2 variants