A Comparison of Materials for Dry Surface Cleaning Soot-Coated Papers of Varying Roughness: Assessing Efficacy, Physical Surface Changes, and Residue

To provide detailed information to aid conservators faced with soot removal, a survey comparing the removal of lamp black pigment, serving as a model soot, from three sample papers of differing roughness is presented. The efficacy of ten different dry surface cleaning materials—including sponges, firm and kneaded erasers, eraser crumbs, a cleaning putty, a solvent-free polydimethylsiloxane elastomer, and a dry swab—have been assessed using a handheld color spectrophotometer and image analysis of photomicrographs. Inspection of the cleaned substrates with a portable optical microscope revealed detailed information into how physical properties of cleaning materials influence the location of residual soot on the surface. 3D digital light microscopy and Fourier-transform infrared spectroscopy were used to assess physical changes to the paper surface and to identify potential residues from the materials after cleaning, respectively. The results of this model study were compared with spot cleaning tests performed on a fire-damaged paper book cover. Limited access to laboratory spaces during Covid-19 lockdown motivated this research to focus on affordable ways to perform hands-on technical research outside of the laboratory, details of which are noted throughout this paper. © American Institute for Conservation of Historic and Artistic Works 2023.

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.