Safe and sensitive antiviral screening platform based on recombinant human coronavirus OC43 expressing the luciferase reporter gene

La transcription des symboles et des caractères spéciaux utilisés dans la version originale de ce résumé n’a pas été possible en raison de limitations techniques. La version correcte de ce résumé peut être lue en utilisant l'adresse URL du DOI. The symbols and special characters used in the original abstract could not be transcribed due to technical problems. Please use the URL address of the DOI version to read the abstract. Human coronaviruses (HCoVs) cause 15 to 30% of mild upper respiratory tract infections. However, no specific antiviral drugs are available to prevent or treat HCoV infections to date. Here, we developed four infectious recombinant HCoVs-OC43 (rHCoVs-OC43) which express the Renilla luciferase (Rluc) reporter gene. Among these four rHCoVs-OC43, rOC43-ns2DelRluc (generated by replacing ns2 with the Rluc gene) showed robust luciferase activity with only a slight impact on its growth characteristics. Additionally, this recombinant virus remained stable for at least 10 passages in BHK-21 cells. rOC43-ns2DelRluc was comparable to its parental wild-type virus (HCoV-OC43-WT) with respect to the quantity of the antiviral activity of chloroquine and ribavirin. We showed that chloroquine strongly inhibited HCoV-OC43 replication in vitro, with a 50% inhibitory concentration (IC50) of 0.33 μM. However, ribavirin showed inhibition of HCoV-OC43 replication only at high concentrations which may not be applicable to humans in clinical treatment, with an IC50 of 10 μM. Furthermore, using a luciferase-based small interfering RNA (siRNA) screening assay, we identified double-stranded-RNA-activated protein kinase (PKR) and DEAD box RNA helicases (DDX3X) that exhibited antiviral activities, which were further verified by the use of HCoV-OC43-WT. Therefore, rOC43-ns2DelRluc represents a promising safe and sensitive platform for high-throughput antiviral screening and quantitative analysis of viral replication

Oral abstracts of the 21st International AIDS Conference 18-22 July 2016, Durban, South Africa

The rate at which HIV-1 infected individuals progress to AIDS is highly variable and impacted by T cell immunity. CD8 T cell inhibitory molecules are up-regulated in HIV-1 infection and associate with immune dysfunction. We evaluated participants (n=122) recruited to the SPARTAC randomised clinical trial to determine whether CD8 T cell exhaustion markers PD-1, Lag-3 and Tim-3 were associated with immune activation and disease progression.Expression of PD-1, Tim-3, Lag-3 and CD38 on CD8 T cells from the closest pre-therapy time-point to seroconversion was measured by flow cytometry, and correlated with surrogate markers of HIV-1 disease (HIV-1 plasma viral load (pVL) and CD4 T cell count) and the trial endpoint (time to CD4 count <350 cells/μl or initiation of antiretroviral therapy). To explore the functional significance of these markers, co-expression of Eomes, T-bet and CD39 was assessed.Expression of PD-1 on CD8 and CD38 CD8 T cells correlated with pVL and CD4 count at baseline, and predicted time to the trial endpoint. Lag-3 expression was associated with pVL but not CD4 count. For all exhaustion markers, expression of CD38 on CD8 T cells increased the strength of associations. In Cox models, progression to the trial endpoint was most marked for PD-1/CD38 co-expressing cells, with evidence for a stronger effect within 12 weeks from confirmed diagnosis of PHI. The effect of PD-1 and Lag-3 expression on CD8 T cells retained statistical significance in Cox proportional hazards models including antiretroviral therapy and CD4 count, but not pVL as co-variants.Expression of ‘exhaustion’ or ‘immune checkpoint’ markers in early HIV-1 infection is associated with clinical progression and is impacted by immune activation and the duration of infection. New markers to identify exhausted T cells and novel interventions to reverse exhaustion may inform the development of novel immunotherapeutic approaches

Feasibility study of mitigation and suppression strategies for controlling COVID-19 outbreaks in London and Wuhan

Recent outbreaks of coronavirus disease 2019 (COVID-19) has led a global pandemic cross the world. Most countries took two main interventions: suppression like immediate lockdown cities at epicenter or mitigation that slows down but not stopping epidemic for reducing peak healthcare demand. Both strategies have their apparent merits and limitations; it becomes extremely hard to conduct one intervention as the most feasible way to all countries. Targeting at this problem, this paper conducted a feasibility study by defining a mathematical model named SEMCR, it extended traditional SEIR (Susceptible-Exposed-Infectious-Recovered) model by adding two key features: a direct connection between Exposed and Recovered populations, and separating infections into mild and critical cases. It defined parameters to classify two stages of COVID-19 control: active contain by isolation of cases and contacts, passive contain by suppression or mitigation. The model was fitted and evaluated with public dataset containing daily number of confirmed active cases including Wuhan and London during January 2020 and March 2020. The simulated results showed that 1) Immediate suppression taken in Wuhan significantly reduced the total exposed and infectious populations, but it has to be consistently maintained at least 90 days (by the middle of April 2020). Its success heavily relied on sufficiently external support from other places of China. This mode was not suitable to other countries that have no sufficient health resources. 2) In London, it is possible to take a hybrid intervention of suppression and mitigation for every 2 or 3 weeks over a longer period to balance the total infections and economic loss. While the total infectious populations in this scenario would be possibly 2 times than the one taking suppression, economic loss and recovery of London would be less affected. 3) Both in Wuhan and London cases, one important issue of fitting practical data was that there were a large portion (probably 62.9% in Wuhan) of self-recovered populations that were asymptomatic or mild symptomatic. These people might think they have been healthy at home and did not go to hospital for COVID-19 tests. Early release of intervention intensity potentially increased a risk of the second outbreak

TiO2 nanosheets synthesized by atomic layer deposition for photocatalysis

AbstractTwo-dimensional TiO2 nanosheets were synthesized by atomic layer deposition (ALD) on dissolvable sacrificial polymer layer. The photocatalytic performance of free-standing TiO2 nanosheets prepared with different numbers of ALD cycles (100, 300, 500, and 1000) were investigated by evaluating the degradation rates of methyl orange solutions. It is shown that the photocatalytic activity increases due to Ti3+ defect and the locally ordered structures in amorphous TiO2 nanosheets. The difference in the surface areas of nanosheets may also play a crucial role in the photocatalytic activity. The results obtained in this work can have potential applications in fields like water splitting and dye-sensitized solar cells