Ace2 Substrate Cleavage Effect Associated with Covid-19 Patient Plasma Immunoglobulin

Background: Many mechanisms responsible for COVID-19 pathogenesis are well-known, but COVID-19 includes features with unclear pathogenesis, like autonomic dysregulation, coagulopathies, and high levels of inflammation. The SARS-CoV-2 spike protein receptor binding domain (RBD) receptor is angiotensin converting enzyme 2 (ACE2). We hypothesized that some COVID-19 patients may develop immunoglobulins (Igs) that have negative molecular image of RBD sufficiently similar to ACE2 to yield ACE2-like catalytic activity - ACE2-like 'abzymes'. Method(s): To explore this hypothesis, we studied 67 patients hospitalized with COVID-19 who had disodium ethylenediaminetetraacetate (EDTA) anticoagulated plasma samples available, obtained about 7 days after admission. We used commercially available fluorometric ACE2 assays (Abcam), and a SpectraMax M5 microplate reader (Molecular Devices), measuring Relative Fluorescent Unit (RFU, Ex/Em = 320/420 nm;RFU) in a kinetic mode every 20 min at 37C. ACE2 inhibitor provided in the assay kit was used for additional controls. In some control experiments, we added Zn2+ to plasma, or conducted serial dilutions to decrease Zn2+. To deplete Igs, we passed plasma samples through a 0.45 mum filter to remove large particles, then passed the material through 100kDa cut-off ultrafiltration membrane (PierceTM) columns, and finally used protein A/G Magnetic Beads (Life Technologies) to specifically deplete Ig, removing >99.99% of Ig as assessed with a human IgG ELISA Kit (Abcam). Result(s): ACE2 is a metalloprotease that requires Zn2+ for activity. However, we found that the plasma of 11 of the 67 patients could cleave a synthetic ACE2 peptide substrate, even though the plasma samples were collected using EDTA anticoagulant. When we spiked plasma with synthetic ACE2, no ACE2 substrate cleavage activity was observed unless Zn2+ was added, or the plasma was diluted to decrease EDTA concentration. After processing samples by size exclusion and protein A/G adsorption, the plasma samples did not cleave the ACE2 substrate peptide. Conclusion(s): The data suggest that some patients with COVID-19 develop Igs with activity capable of cleaving synthetic ACE2 substrate. Since abzymes can exhibit promiscuous substrate specificities compared to the enzyme whose active site image they resemble, and since proteolytic cascades regulate physiologic processes, anti-RBD abzymes may contribute to some otherwise obscure features of COVID-19 pathogenesis. (Figure Presented).

Ion Mobility Spectrometry in Clinical and Emergency Setting: Research and Potential Applications

Interest in the use of GC-IMS for the detection of volatiles has seen a rapid expansion over the last decade. The following chapter will focus on classical GC-IMS and its research applications in the potential for diagnosis, rapid testing and biomarker discovery, with an emphasis on breath testing. Breath analysis via GC-IMS has enormous potential in many clinical areas including screening for pulmonary diseases, infections and toxins. Due to the technology's small footprint, robustness in various environments and ease of use, there have been many studies looking at its potential utility in the clinical field, including its use as a screening tool for SARS-CoV-2 infections. There remain limitations to the device usage and data processing which are discussed throughout the chapter. An introduction to its fundamentals, standardisation, breath collection methods and active areas of research and development will be covered. Copyright © 2022, The Author(s), under exclusive license to Springer Nature Switzerland AG.

Hospitalisation and mortality risk of SARS-COV-2 variant omicron sub-lineage BA.2 compared to BA.1 in England.

The Omicron variant of SARS-CoV-2 became the globally dominant variant in early 2022. A sub-lineage of the Omicron variant (BA.2) was identified in England in January 2022. Here, we investigated hospitalisation and mortality risks of COVID-19 cases with the Omicron sub-lineage BA.2 (n = 258,875) compared to BA.1 (n = 984,337) in a large cohort study in England. We estimated the risk of hospital attendance, hospital admission or death using multivariable stratified proportional hazards regression models. After adjustment for confounders, BA.2 cases had lower or similar risks of death (HR = 0.80, 95% CI 0.71-0.90), hospital admission (HR = 0.88, 95% CI 0.83-0.94) and any hospital attendance (HR = 0.98, 95% CI 0.95-1.01). These findings that the risk of severe outcomes following infection with BA.2 SARS-CoV-2 was slightly lower or equivalent to the BA.1 sub-lineage can inform public health strategies in countries where BA.2 is spreading.

Measles, Mumps, and Rubella Booster Immunization Practices

Reported cases of mumps infection in the United States (U.S.) have dropped since the introduction of the single-component mumps vaccine in 1967. After introduction of the multi-component measles, mumps, rubella (MMR) vaccine, cases in the U.S. and worldwide fell to the point where the International Task Force for Disease Eradication identified mumps for eventual global eradication. By 1991, all military recruits received an MMR vaccine. By 2010, the Department of Defense (DoD) had adopted a policy of immunizing recruits with MMR vaccine only if their antibody titers to measles or rubella had dropped below threshold levels established by the commercial testing laboratories as indicative of immunity. As part of a 2010 Defense Health Board (DHB) review of MMR immunization practices by the Department of the Navy, the DHB recommended that the Navy continue the practice of MMR immunization based on serosurveillance, but that universal MMR vaccination be re-instituted in the event of an increased risk of a mumps outbreak.