Biology subjects

Merits, A.

Publications and source records attributed to Merits, A..

21 records · Page 2Linked to original sources

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↗

bioRxiv2019

Pan-viral protection against arboviruses by targeting inoculation site-based skin macrophages

Arthropod-borne viruses (arboviruses) are important human pathogens for which there are no specific antiviral medicines. The large number of genetically-distinct arbovirus species, coupled with the unpredictable nature of their outbreaks, has made developing virus-specific anti-viral medicines challenging. Instead, we have defined and targeted a key aspect of the host innate immune response to virus at the arthropod bite that is common to all arbovirus infections, potentially circumventing the need for virus-specific therapies at this site. Using mouse models and human skin explants, we identify innate immune responses by dermal macrophages in the skin as a key determinant of disease severity. Post-exposure treatment of the inoculation site by a topical innate immune agonist significantly suppressed both the local and subsequent systemic course of infection and improved clinical outcome in mice to infection with a variety of arboviruses from the Alphavirus, Flavivirus and Orthobunyavirus genuses. In the absence of treatment, anti-viral interferon expression to virus in the skin was restricted to dermal dendritic cells. In contrast, targeting the more populous skin-resident macrophages with an immune agonist elicited protective responses in key cellular targets of virus that otherwise replicated virus to high levels. By defining and targeting a key aspect of the innate immune response to virus at the mosquito bite site, we have shown that it is possible to improve outcome to infection by targeting pathways activated at the site of inoculation, and thereby identified a putative new strategy for limiting disease following infection with a variety of genetically-distinct arboviruses.\n\nOne-sentence summaryWe demonstrate that activation of innate immune responses to arbovirus at the mosquito bite is a limiting factor for preventing efficient systemic dissemination of virus and that therapeutic targeting of skin-resident macrophages can have defining inhibitory effects on the later systemic course.

immunology↗

bioRxiv2018

Persistent Chikungunya Virus Replication in Human Cells is Associated with Presence of Stable Cytoplasmic Granules Containing Non-structural Protein 3

Chikungunya virus (CHIKV), a mosquito-borne human pathogen, causes a disabling disease characterized by severe joint pain that can persist for weeks, months or even years in patients. The non-structural protein 3 (nsP3) plays essential roles during acute infection, but little is known about the function of nsP3 during chronic disease. Here, we used sub-diffraction multi-color microscopy for a spatial and temporal analysis of CHIKV nsP3 within human cells that persistently replicate viral RNA. Round cytoplasmic granules of various sizes (i) contained nsP3 and G3BP Stress Granule Assembly factor; (ii) were next to double-stranded RNA foci, and nsP1-positive structures; and (iii) made contact with markers of the cytoskeleton and cellular structures, such as early endosomes and nucleopores. Analysis of protein turnover and mobility by live-cell microscopy revealed that granules could persist for hours to days, can accumulate newly synthesized protein, and move at differently through the cytoplasm. Granules also had a static internal architecture and were stable in cell lysates. Whereas cells with active replication and stable nsP3-granules did not respond to oxidative stress, refractory cells that had cleared the non-cytotoxic replicon could. In summary, nsP3 can form uniquely stable granular structures that persist long-term within the host cell. This continued presence of viral and cellular protein-complexes has implications for the study of the pathogenic consequences of lingering CHIKV infection and the development of strategies to mitigate the burden of chronic musculoskeletal disease brought about by a medically important arthropod-borne virus (arbovirus).\n\nImportanceChikungunya virus (CHIKV) is a re-emerging alphavirus transmitted by mosquitos and causes widespread transient sickness but also chronic disease affecting muscles and joints. Although no approved vaccines or antivirals are available, a better understanding of the viral life cycle and the role of individual viral proteins can aid in identifying new therapeutic targets. Advances in microscopy and persistent CHIKV model systems now allow researchers to study viral proteins within controlled laboratory environments. Here we established human cells that stably replicate viral RNA and express a tagged version of non-structural protein 3. The ability to track this viral protein within the host cell and during persistent replication can benefit fundamental research efforts to better understand long-term consequences of the persistence of viral protein complexes and thereby provide the foundation for new therapeutic targets to control CHIKV infection and treat chronic disease symptoms.

microbiology↗