MANNOSE-BINDING LECTIN (MBL) INHIBITS SARS-CoV-2 INFECTION and REPLICATION in VITRO

Background: Humoral innate immunity consists of a limited, but diverse, set of humoral fluid phase pattern recognition molecules (PRMs) that represent a first line of resistance against microbial invaders by promoting pathogen disposal by phagocytosis, complement activation and inflammation. These factors encompass complement, ficolin, collectin and pentraxin family of proteins. Methods: We have analyzed the activity of PRMs for their potential capacity of inhibiting SARS-CoV-2 entry and replication into epithelial cells by a microneutralization assay based on a lentiviral particles pseudotyped with the SARS-CoV-2 spike protein in HEK293T cells overexpressing the angiotensin converting enzyme 2 (ACE2). Either SARS-CoV-2 or target cells were incubated with Mannose Binding Lectin (MBL, concentration range: 1-50 μ g/ml) to further characterize its anti-viral activity for 1 h prior to infection in both human Calu-3 cells and air-liquid interface cultures of human bronchial epithelial cells (HBEC). Binding experiments were carried out with SARS-CoV-2 Spike protein and recombinant MBL to further investigate its antiviral action. Results: Among 12 PRMs tested, only MBL inhibited viral entry in the pseudotyped neutralization assay. Furthermore, MBL protein inhibited SARS-CoV-2 viral replication in Calu-3 and HBEC by ca. one log10 at the top concentration (10 μ g/ml and 50 μ g/ml, respectively). MBL antiviral activity was confirmed also against alpha, beta and gamma SARS-CoV-2 variants of concern. Binding experiments showed that MBL specifically interacts with the trimeric form of SARS-CoV-2 spike. Conclusion: MBL binds to the Spike protein in its active trimeric conformation leading to the inhibition of SARS-CoV-2 infection and replication in vitro. These results suggest that MBL possesses an antiviral activity against SARS-CoV-2 that could bear therapeutic potential.

Impact of Remdesivir on SARS-CoV-2 Clearance in a Real-Life Setting: A Matched-Cohort Study

Background. Evidence regarding the impact of remdesivir (RDV) on SARSCoV-2 viral clearance (VC) is scarce. Aim of this study was to compare VC timing in COVID-19 patients who received RDV with those who did not. Methods. Matched-cohort study conducted (25 February 2020-15 April 2021) at the IRCSS San Raffaele, Milan, Italy. The study enrolled hospitalized patients with pneumonia and a SARS-CoV-2 positive nasopharyngeal swab (NPS) at admission and at least one NPS during follow-up. Follow-up started at hospital admission and ended at the date of the first negative NPS (within 30 days after discharge). Patients who received RDV (cases) and patients who did not (controls) were matched based on age (±5 years), sex and PaO2/FiO2 (P/F;±10 mmHg) values at admission. NPS were analyzed with RT-PCR. Results described as median (IQR) or frequency (%). Time to VC was estimated with Kaplan-Meier curve and compared with log-rank test. Results. 648 patients were enrolled: 216 cases and 432 controls. Patients' characteristics at admission are reported in Table 1. VC was observed in 490 patients (75.6%) in a median time of 25 (16-34) days. Overall, time to VC was similar in patients receiving or not receiving remdesivir (p=0.519). However, time to VC was different when considering both the use of RDV (yes vs no) and age (≤ or > 63 years), as shown in Figure 1A. A significant finding was also observed considering the use of RDV and P/F values at admission (≤ or > 200 mmHg), as reported in Figure 1B. Among the 490 patients who reached VC during follow-up, overall time to VC was similar in patients receiving or not receiving RDV (p=0.075;Figure 2A);however, RDV use was associated with a higher probability of VC in the subgroup of patients with P/F admission values ≤ 200mmHg (p=0.035;Figure 2B), in the age group 55-65 years (p=0.025;Figure 2C) and in patients with comorbidities (p=0.028). Time to viral clearance among the 490 patients who reached VC during follow-up. Panel A: time to VC according to RDV use. Panel B: time to VC according to RDV and P/F ratio value at admission. Panel C: time to VC according to RDV in the age group 55-65 years. Conclusion. Time to viral clearance was similar in patients receiving or not receiving remdesivir;however the use of RDV was associated with a benefit on time to viral clearance in younger patients and in those with a P/F ratio at admission ≤200 mmHg.

SARS-CoV-2 detection in primary thyroid sarcoma: coincidence or interaction?

INTRODUCTION: Thyroid dysfunctions associated with SARS-CoV-2 are emerging in scientific literature. During the second COVID-19 epidemic spread, we evaluated a patient with the suspect of subacute thyroiditis. METHODS AND RESULTS: Specimen from fine-needle aspiration of a hypoechoic undefined area was analyzed for cytology and for SARS-CoV-2 detection. SARS-CoV-2 was retrieved by real-time polymerase chain reaction on the cytologic sample, which was then cultured on Vero E6 cells and demonstrated to be cytopathic. Whole-genome sequence was deposited. Histological exam diagnosed a rare case of primary thyroid sarcoma with diffuse and strong expression of mouse double minute 2 homolog (MDM2) oncoprotein. Ultrastructural examination confirmed, in several neoplastic cells, the presence of viral particles in cytoplasmic vacuoles. CONCLUSIONS: In our hypothesis, SARS-CoV-2 and sarcoma coexistence could represent a synergistic interplay, ultimately favoring both viral persistence and tumor proliferation: the overexpression of MDM2 in tumor cells might have generated a favorable immunological niche for SARS-CoV-2 localization and, in turn, SARS-CoV-2 could have favored tumor growth by inducing MDM2-mediated p53 downregulation. Functional studies are needed to confirm this suggestive pathway.

The efficacy of ultraviolet light-emitting technology against coronaviruses: a systematic review.

The ongoing pandemic of COVID-19 has underlined the importance of adopting effective infection prevention and control (IPC) measures in hospital and community settings. Ultraviolet (UV)-based technologies represent promising IPC tools: their effective application for sanitation has been extensively evaluated in the past but scant, heterogeneous and inconclusive evidence is available on their effect on SARS-CoV-2 transmission. With the aim of pooling the available evidence on the efficacy of UV technologies against coronaviruses, we conducted a systematic review following PRISMA guidelines, searching Medline, Embase and the Cochrane Library, and the main clinical trials' registries (WHO ICTRP, ClinicalTrials.gov, Cochrane and EU Clinical Trial Register). Quantitative data on studies' interventions were summarized in tables, pooled by different coronavirus species and strain, UV source, characteristics of UV light exposure and outcomes. Eighteen papers met our inclusion criteria, published between 1972 and 2020. Six focused on SARS-CoV-2, four on SARS-CoV-1, one on MERS-CoV, three on seasonal coronaviruses, and four on animal coronaviruses. All were experimental studies. Overall, despite wide heterogenicity within included studies, complete inactivation of coronaviruses on surfaces or aerosolized, including SARS-CoV-2, was reported to take a maximum exposure time of 15 min and to need a maximum distance from the UV emitter of up to 1 m. Advances in UV-based technologies in the field of sanitation and their proved high virucidal potential against SARS-CoV-2 support their use for IPC in hospital and community settings and their contribution towards ending the COVID-19 pandemic. National and international guidelines are to be updated and parameters and conditions of use need to be identified to ensure both efficacy and safety of UV technology application for effective infection prevention and control in both healthcare and non-healthcare settings.