ABSTRACT
Coronavirus induced disease-19 (COVID-19), caused by the SARS-CoV-2 remains a major global health challenge. Human endogenous retroviruses (HERVs) represent retroviral elements that got integrated into the ancestral human genome. HERVs are important in development and diseases, including cancer, inflammation and viral infections. Here, we analyzed the expression of several HERVs in SARS-CoV-2 infected cells and observed increased activity of HERV-E, HERV-V, HERV-FRD, HERV-MER34, HERV-W and HERV-K-HML2. In contrast, HERV-R-envelope was downregulated in cell-based models and COVID-19 patient PBMCs. HERV-R overexpression inhibited SARS-CoV-2 replication, suggesting its antiviral action. Further studies demonstrated the role of extracellular signal-regulated kinase (ERK) in regulating HERV-R antiviral activity. Cross-talk between the ERK and p38 MAPK controls HERV-R envelope synthesis, which in turn modulates the replication of SARS-CoV-2. These findings establish the importance of HERV-R envelope as a host restriction factor against SARS-CoV-2 and illustrate the advantage of integration and evolutionary maintenance of retroviral-elements in the human genome.
Subject(s)
Coronavirus Infections , Severe Acute Respiratory Syndrome , Neoplasms , Virus Diseases , COVID-19 , InflammationABSTRACT
Fully effective vaccines for viruses such as Influenza and SARS-CoV-2 must elicit a diverse repertoire of antibodies against multiple drifted virus strains. However, how to achieve a diverse response has no general solution except to combine multiple strains, which risks diluting the response for all strains included. Here, we describe the synthesis of a universal, toll-like receptor 7 agonist (TLR7)-nanoparticle adjuvant, TLR7-NP, constructed from TLR7 agonist-initiated ring-opening polymerization of lactide and self-assembly with poly(ethylene glycol)- b -poly(lactic-co-glycolic acid). When mixed with Alum-adsorbed antigens, this TLR7-NP adjuvant elicited cross-reactive antibodies for both dominant and subdominant epitopes, as well as antigen-specific CD8 + T cell responses. TLR7-NPs adjuvanted influenza subunit vaccine successfully protected mice from heterologous viral challenge. TLR7-NPs also enhanced the antibody response to a SARS-CoV-2 subunit vaccine against multiple variants and revealed the mobilization of a virus-like response. We further demonstrate enhanced antigen-specific responses in human tonsil organoids with this novel adjuvant.
ABSTRACT
Severe acute respiratory syndrome-coronavirus-2 (SARS-CoV-2) is a positive-strand RNA virus. Viral genome is capped at the 5'-end, followed by an untranslated region (UTR). There is poly-A tail at 3'-end, preceded by an UTR. Self-interaction between the RNA regulatory elements present within 5'- and 3'-UTRs as well as their interaction with host/virus-encoded proteins mediate the function of 5'- and 3'-UTRs. Using RNA-protein interaction detection (RaPID) assay coupled to liquid chromatography with tandem mass-spectrometry, we identified host interaction partners of SARS-CoV-2 5'- and 3'-UTRs and generated an RNA-protein interaction network. By combining these data with the previously known protein-protein interaction data proposed to be involved in virus replication, we generated the RNA-protein-protein interaction (RPPI) network, likely to be essential for controlling SARS-CoV-2 replication. Notably, bioinformatics analysis of the RPPI network revealed the enrichment of factors involved in translation initiation and RNA metabolism. Lysosome-associated membrane protein-2a (Lamp2a) was one of the host proteins that interact with the 5'-UTR. Further studies showed that Lamp2 level is upregulated in SARS-CoV-2 infected cells and overexpression of Lamp2a and Lamp2b variants reduced viral RNA level in infected cells and vice versa. In summary, our study provides an useful resource of SARS-CoV-2 5'- and 3'-UTR binding proteins and reveal the antiviral function of host Lamp2 protein.