Biology subjects

Zusinaite, E.

Publications and source records attributed to Zusinaite, E..

9 recordsLinked to original sources

bioRxiv2026

Dengue virus NS1 undergoes partial nuclear translocation to modulate host transcription and support viral replication

The dengue virus (DENV) non-structural protein 1 (NS1) is a glycoprotein highly conserved among mosquito-borne orthoflaviviruses. NS1 is typically localized in the lumen of the endoplasmic reticulum, where it forms part of the replication complexes, and is also exposed at the plasma membrane. In addition, NS1 is secreted as a lipoprotein. Here, using a combination of approaches, including confocal microscopy with deconvolution, in situ analysis, and biochemical cell fractionation, we show that a substantial fraction of NS1 (up to 30%) translocates to the nucleus during infection. We identified a conserved, structurally exposed bipartite nuclear localization signal (NLS) within NS1. Pharmacological inhibition with ivermectin and site-directed mutagenesis of the NLS in recombinant confirmed that nuclear import of NS1 is an active process, dependent on the classical importin /{beta} pathway. Notably, both dimeric and multimeric forms of NS1 were detected in the nucleus in association with nuclear lamin. Introduction of the NLS mutations into DENV2 infectious clones resulted in a non-viable virus. Production of virus progeny and completion of the replicative cycle by the mutant genomes could be rescued by trans-complementation with wild-type NS1, but not with an NLS-mutated NS1, indicating that an NS1 nuclear phase is required for a productive infection. Transcriptomic analysis by RNA-seq further revealed that NS1 functions depend on its subcellular location. Nuclear NS1 induced the overexpression of genes associated with DNA-binding transcription factors, whereas NLS-mutated NS1, retained in the cytoplasm, failed to induce these genes and instead triggered pro-inflammatory and metabolic responses. Together, these findings reveal a previously unrecognized nuclear phase of NS1 that is required for an efficient viral life cycle, redefining NS1 as a modulator of the host transcriptional environment. These findings also suggest new avenues for antiviral and vaccine development. Authors summaryDengue virus NS1 is a glycoprotein of approximately 45-50 kDa that rapidly dimerizes after proteolytic maturation. Dimeric NS1 is located in the lumen of the endoplasmic reticulum where it acts as a scaffold component of the viral replication complexes. In addition, NS1 is secreted from infected cells as a tetramer or hexamer and circulates in the serum of infected individuals during the acute phase of dengue disease. Circulating NS1 is widely used as a diagnostic marker and has also been associated with dengue pathogenesis through several mechanisms. Here, we expand the current understanding of DENV NS1 by identifying a previously unrecognized and essential nuclear location of this protein. We show that NS1 contains a conserved nuclear localization signal that mediates import into the nucleus via the classical import pathway. Using wild-type and NLS-mutated infectious clones, we demonstrated that nuclear localization of NS1 is required for completion of the DENV replicative cycle. Transcriptomic analysis further revealed that nuclear NS1 promotes the expression of host genes involved in nucleic acid metabolism, whereas retention of NS1 in the cytoplasm triggers an antiviral and inflammatory response. Together, these findings identify the nucleus as an important site of dengue virus-host interactions and redefine NS1 as a regulator of the host transcriptional environment during infection.

microbiology↗

bioRxiv2024

Altered spike dynamics drives immune evasion of SARS-CoV-2

Escape from protective immunity has been a defining feature of the COVID-19 pandemic and is widely attributed to mutations in neutralizing antibody epitopes within the receptor binding domain (RBD) of the SARS-CoV-2 spike glycoprotein. We investigated whether this paradigm accounts for the escape of Omicron lineage viruses from broadly neutralizing antibodies (bNAbs) targeting conserved RBD epitopes. We found that mutational erosion of bNAb binding epitopes was not a major driver of Omicron immune escape. Viruses carrying RBDs from highly resistant contemporary Omicron variants were potently neutralized by bNAbs when those RBDs were placed into an ancestral Wuhan-like spike backbone. Similarly, sera collected during the pre-Omicron era from individuals vaccinated with Wuhan-based vaccines retained robust RBD-specific neutralizing activity against these chimeric viruses. Mechanistically, bNAb treatment triggered exposure of the S2 cleavage site in neutralization-sensitive but not resistant spike proteins, indicating that bNAb susceptibility reflects differences in spike propensity for antibody-induced premature conformational transition. These findings show that, rather than escaping through mutation of bNAb epitopes, SARS-CoV-2 has evolved spike variants with altered conformational dynamics that resist bNAb-induced destabilization of the prefusion spike trimer.

immunology↗

bioRxiv2023

A Zika virus-responsive sensor-effector system in Aedes aegypti

Zika virus (ZIKV) is a recently re-emerged flavivirus transmitted primarily through the bite of an infected mosquito, Aedes aegypti being the main vector. ZIKV infection is associated with a range of adverse effects; infection during pregnancy can lead to foetal abnormalities, including microcephaly. Lacking a licensed vaccine, or specific therapeutics, control of ZIKV transmission focuses on vector control. However, in most transmission settings, current methods are insufficient to successfully control ZIKV, or other similarly-transmitted arboviruses such as dengue and chikungunya viruses. This has stimulated interest in genetics-based methods, either to reduce the number of mosquitoes ("population suppression"), or to make mosquitoes less able to transmit ("population modification"). Here, we describe a method to selectively eliminate infected mosquitoes, using a virus sensor inserted into the mosquito genome and coupled to a quorum-counting lethal effector. In mosquitoes, ZIKV normally establishes persistent, lifelong infection; survival of these infected mosquitoes is crucial to transmission potential. Correspondingly, removal of infected mosquitoes can reduce vectorial capacity of a mosquito population, i.e. ability to transmit. Since relatively few mosquitoes become infected, typically <2%, engineered hypersensitivity to ZIKV would have only a modest population-level fitness cost, and lower still if transmission were successfully reduced by such means.

bioengineering↗

bioRxiv2022

Broad-spectrum mono- and combinational drug therapies for global viral pandemic preparedness

Broadly effective antiviral therapies must be developed to be ready for clinical trials, which should begin soon after the emergence of new life-threatening viruses. Here, we pave the way towards this goal by analyzing conserved druggable virus-host interactions, mechanisms of action and immunomodulatory properties of broad-spectrum antivirals (BSAs), routes of BSA delivery, and BSA interactions with other antivirals. Based on the analysis we developed scoring systems, which allowed us to predict novel BSAs and BSA-containing drug combinations (BCCs). Thus, we have developed a new strategy to broaden the spectrum of BSA indications and predict novel mono-and combinational therapies that can help better prepare for imminent future viral outbreaks. O_FIG O_LINKSMALLFIG WIDTH=200 HEIGHT=141 SRC="FIGDIR/small/476444v2_ufig1.gif" ALT="Figure 1"> View larger version (47K): org.highwire.dtl.DTLVardef@7fee8dorg.highwire.dtl.DTLVardef@1069131org.highwire.dtl.DTLVardef@2632bforg.highwire.dtl.DTLVardef@1cdcbf0_HPS_FORMAT_FIGEXP M_FIG C_FIG

microbiology↗

bioRxiv2021

Active components of commonly prescribed medicines affect influenza A virus-host cell interaction: a pilot study

BackgroundEvery year, millions of people are hospitalized, and thousands die from influenza A virus (FLUAV) infection. Most cases of hospitalizations and death occur among elderly. Many of these elderly patients are reliant on medical treatment of underlying chronic diseases, such as arthritis, diabetes, and hypertension. We hypothesized that the commonly prescribed medicines for treatment of underlying chronic diseases can affect host responses to FLUAV infection, and thus contribute to morbidity and mortality associated with influenza. Therefore, the aim of this study was to examine whether commonly prescribed medicines could affect host responses to virus infection in vitro. MethodsWe first identified 45 active compounds of commonly prescribed medicines. Then we constructed a drug-target interaction network and identified potential implication of these interactions for FLUAV-host cell interplay. Finally, we tested the effect of 45 drugs on viability, transcription and metabolism of mock- and FLUAV-infected human retinal pigment epithelial (RPE) cells. ResultsIn silico drug-target interaction analysis revealed that many drugs, such as atorvastatin, candesartan, and hydroxocobalam, could target and modulate FLUAV-host cell interaction. In vitro experiments showed that these and other compounds at non-cytotoxic concentrations differently affected transcription and metabolism of mock- and FLUAV-infected cells. ConclusionMany commonly prescribed drugs modulate FLUAV-host cell interactions in silico and in vitro and, therefore, could affect their interplay in vivo, thus, contributing to morbidity and mortality of patients with influenza virus infections.

pharmacology and toxicology↗

bioRxiv2021

Synergistic interferon alpha-based drug combinations inhibit SARS-CoV-2 and other viral infections in vitro

There is an urgent need for new antivirals with powerful therapeutic potential and tolerable side effects. In the present study, we found that recombinant human interferon-alpha (IFNa) triggers intrinsic and extrinsic cellular antiviral responses, as well as reduces replication of severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) in vitro. Although IFNa alone was insufficient to completely abolish SARS-CoV-2 replication, combinations of IFNa with remdesivir or other antiviral agents (EIDD-2801, camostat, cycloheximide, or convalescent serum) showed strong synergy and effectively inhibited SARS-CoV-2 infection in human lung epithelial Calu-3 cells. Furthermore, we showed that the IFNa-remdesivir combination suppressed virus replication in human lung organoids, and that its single prophylactic dose attenuated SARS-CoV-2 infection in lungs of Syrian hamsters. Transcriptome and metabolomic analyses showed that the combination of IFNa-remdesivir suppressed virus-mediated changes in infected cells, although it affected the homeostasis of uninfected cells. We also demonstrated synergistic antiviral activity of IFNa2a-based combinations against other virus infections in vitro. Altogether, our results indicate that IFNa2a-based combination therapies can achieve higher efficacy while requiring lower dosage compared to monotherapies, making them attractive targets for further pre-clinical and clinical development.

microbiology↗

bioRxiv2020

Identification of novel antiviral drug combinations in vitro and tracking their development

Combination therapies have become a standard for the treatment for HIV and HCV infections. They are advantageous over monotherapies due to better efficacy and reduced toxicity, as well as the ability to prevent the development of resistant viral strains and to treat viral co-infections. Here, we identify several new synergistic combinations against emerging and re-emerging viral infections in vitro. We observed synergistic activity of nelfinavir with investigational drug EIDD-2801 and convalescent serum against SARS-CoV-2 infection in human lung epithelial Calu-3 cells. We also demonstrated synergistic activity of vemurafenib combination with emetine, homoharringtonine, gemcitabine, or obatoclax against echovirus 1 infection in human lung epithelial A549 cells. We also found that combinations of sofosbuvir with brequinar and niclosamide were synergistic against HCV infection in hepatocyte derived Huh-7.5 cells, whereas combinations of monensin with lamivudine and tenofovir were synergistic against HIV-1 infection in human cervical TZM-bl cells. Finally, we present an online resource that summarizes novel and known antiviral drug combinations and their developmental status. Overall, the development of combinational therapies could have a global impact improving the preparedness and protection of the general population from emerging and re-emerging viral threats.

microbiology↗

bioRxiv2020

Antiviral options against SARS-CoV-2 infection

As of June 2020, the number of people infected with severe acute respiratory coronavirus 2 (SARS-CoV-2) continues to skyrocket, with more than 6,5 million cases worldwide. Both the World Health Organization (WHO) and United Nations (UN) has highlighted the need for better control of SARS-CoV-2 infections. However, developing novel virus-specific vaccines, monoclonal antibodies and antiviral drugs against SARS-CoV-2 can be time-consuming and costly. Convalescent sera and safe-in-man broad-spectrum antivirals (BSAAs) are readily available treatment options. Here we developed a neutralization assay using SARS-CoV-2 strain and Vero-E6 cells. We identified most potent sera from recovered patients for treatment of SARS-CoV-2-infected patients. We also screened 136 safe-in-man broad-spectrum antivirals against SARS-CoV-2 infection in Vero-E6 cells and identified nelfinavir, salinomycin, amodiaquine, obatoclax, emetine and homoharringtonine. We found that combinations of virus-directed nelfinavir along with host-directed amodiaquine exhibited the highest synergy. Finally, we developed a website to disseminate the knowledge on available and emerging treatments of COVID-19.

microbiology↗

bioRxiv2019

Critical Nodes of Virus-Host Interaction Revealed Through an Integrated Network Analysis

Viruses are one of the major causes of various acute and chronic infectious diseases and thus a major contributor to the global burden of disease. Several studies have shown how viruses have evolved to hijack basic cellular pathways and evade innate immune response by modulating key host factors and signalling pathways. A collective view of these multiple studies could advance our understanding of viral evasion mechanisms and provide new therapeutic perspectives for the treatment of viral diseases. Here, we performed an integrative meta-analysis to elucidate the 17 different host-virus interactomes. Network and bioinformatics analyses showed how viruses with small genomes efficiently achieve the maximal effect by targeting multifunctional and highly connected host proteins with a high occurrence of disordered regions. We also identified the core cellular process subnetworks that are targeted by all the viruses. Integration with functional RNA interference (RNAi) datasets showed that a large proportion of the targets are required for viral replication. Furthermore, we performed an interactome-informed drug re-purposing screen and identified novel activities for broad-spectrum antiviral agents against hepatitis C virus and human metapneumovirus. Altogether, these orthogonal datasets could serve as a platform for hypothesis generation and follow-up studies to broaden our understanding of the viral evasion landscape.

immunology↗