A Gradient pH-Sensitive Polymer-Based Antiviral Strategy via Viroporin-Induced Membrane Acidification.

Lipid-membrane-targeting strategies hold great promise to develop broad-spectrum antivirals. However, it remains a big challenge to identify novel membrane-based targets of viruses and virus-infected cells for development of precision targeted approaches. Here, it is discovered that viroporins, viral-encoded ion channels, which have been reported to mediate release of hydrogen ions, trigger membrane acidification of virus-infected cells. Through development of a fine-scale library of gradient pH-sensitive (GPS) polymeric nanoprobes, the cellular membrane pH transitions are measured from pH 6.8-7.1 (uninfection) to pH 6.5-6.8 (virus-infection). In response to the subtle pH alterations, the GPS polymer with sharp response at pH 6.8 (GPS6.8 ) selectively binds to virus-infected cell membranes or the viral envelope, and even completely disrupts the viral envelope. Accordingly, GPS6.8 treatment exerts suppressive effects on a wide variety of viruses including SARS-CoV-2 through triggering viral-envelope lysis rather than affecting immune pathway or viability of host cells. Murine viral-infection models exhibit that supplementation of GPS6.8 decreases viral titers and ameliorates inflammatory damage. Thus, the gradient pH-sensitive nanotechnology offers a promising strategy for accurate detection of biological pH environments and robust interference with viruses.

A familial cluster of COVID-19 infection in a northern Chinese region.

OBJECTIVE: Currently, coronavirus disease 2019 (COVID-19) has spread worldwide and become a global health concern. Here, we report a familial cluster of six patients infected with severe acute respiratory coronavirus 2 (SARS-CoV-2) in a northern Chinese region and share our local experience with regard the control of COVID-19. METHODS: The demographic data, clinical features, laboratory examinations, and epidemiological characteristics of enrolled cases were collected and analyzed. Two family members (Cases 1 and 2) had Hubei exposure history and were admitted to the hospital with a confirmed diagnosis of COVID-19; eight familial members who had contact with them during the incubation period underwent quarantine in a hospital. We closely followed up all the family members and analyzed their clinical outcome. RESULTS: Case 3 had negative SARS-CoV-2 reverse transcription-polymerase chain reaction (RT-PCR) results but was suspected to have COVID-19 because of radiographic abnormalities. Cases 4 and 5 developed symptomatic COVID-19. Case 6 was considered an asymptomatic carrier as his SARS-CoV-2 RT-PCR result was positive. The other four family members with close contacts to COVID-19 patients had no evidence of SARS-CoV-2 infection. CONCLUSIONS: Our findings suggest that COVID-19 has infectivity during the incubation period and preventive quarantine is effective for controlling an outbreak of COVID-19 infection.

Manganese nanodepot augments host immune response against coronavirus.

Interferon (IFN) responses are central to host defense against coronavirus and other virus infections. Manganese (Mn) is capable of inducing IFN production, but its applications are limited by nonspecific distributions and neurotoxicity. Here, we exploit chemical engineering strategy to fabricate a nanodepot of manganese (nanoMn) based on Mn2+. Compared with free Mn2+, nanoMn enhances cellular uptake and persistent release of Mn2+ in a pH-sensitive manner, thus strengthening IFN response and eliciting broad-spectrum antiviral effects in vitro and in vivo. Preferentially phagocytosed by macrophages, nanoMn promotes M1 macrophage polarization and recruits monocytes into inflammatory foci, eventually augmenting antiviral immunity and ameliorating coronavirus-induced tissue damage. Besides, nanoMn can also potentiate the development of virus-specific memory T cells and host adaptive immunity through facilitating antigen presentation, suggesting its potential as a vaccine adjuvant. Pharmacokinetic and safety evaluations uncover that nanoMn treatment hardly induces neuroinflammation through limiting neuronal accumulation of manganese. Therefore, nanoMn offers a simple, safe, and robust nanoparticle-based strategy against coronavirus. Electronic Supplementary Material: Supplementary material (RNA-seq data analysis, IFN and ISGs examination, in vitro viral infection, flow cytometry, ICP-MS, DHE staining, and detection of inflammatory factors) is available in the online version of this article at 10.1007/s12274-020-3243-5.