November 23 | Daily COVID-19 LST Report

Understanding the Pathology

· Truncation of orf3b in the circulating SARS-CoV-2 strains has been shown in one study. Microbiologists and Infectious Disease researchers from the University of Hong Kong analyze the genome of SAR-CoV-2 with a particular focus on the orf3b gene, which was found to antagonize type-I interferon activation. Using the sequence data from the GISAID depository, they report a steady increase and persistence of the truncated form of the orf3b gene in SARS-CoV-2 strains worldwide, particularly in countries with the highest confirmed number of COVID-19 cases. The authors note that further research on orf3b's truncation in context with COVID-19's transmissibility and infectivity could be beneficial for guiding future therapeutic and diagnostic developments.

R&D: Diagnosis & Treatments

· Convalescent plasma anti-SARS-CoV-2 spike protein ectodomain and receptor-binding domain IgG correlate with virus neutralization. Researchers primarily at Houston Methodist Hospital analyzed samples of plasma from 68 recovered COVID-19 patients, 2,814 asymptomatic patients, and 10 naive human plasma specimens to investigate the relationship between different neutralizing antibodies and possible ways to screen plasma samples for a virus neutralization (VN) titer ≥ 160. Analysis revealed a positive relationship among spike ectodomain (anti-ECD), anti–receptor-binding domain (anti-RBD) IgG titers, and SARS-CoV-2 virus neutralization (VN) titers, where probability of a VN titer of ≥160 was ≥80% when anti-RBD or anti-ECD titers were ≥1:1350. While no significant relationship was detected between symptom severity and VN titer level, an analysis of 2,814 asymptomatic adults found 14 individuals with sufficient VN titers, with all of those individuals having RBD titers of ≥1:1350. Based on this study's findings, screening for potential anti-SARS-CoV-2 convalescent plasma donors cannot be completed by analysis of symptom severity alone, but spike ectodomain and anti– receptor-binding domain IgG titers may provide a reasonable estimate of VN titer levels.

· There is lack of efficacy of standard doses of ivermectin in severe COVID-19 patients according to a retrospective controlled cohort study. Specialists in global health and infectious disease from Hospital Clinic-Universitat de Barcelona, Spain evaluated efficacy of standard doses of ivermectin in 13 patients with severe COVID-19 against 13 controls without ivermectin. They found no significant differences in clinical or microbiological outcomes between the two groups after 8-11 days of treatment (p >0.999). Authors acknowledge the small sample size in this study, but suggest their results warrant further research involving high-dose ivermectin to better evaluate its efficacy in patients with severe COVID-19.

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