Production of Sars-Cov-2 Membrane Protein as Better Target Protein for Diagnostic Application

Intro: The COVID-19 pandemic is caused by the SARS-CoV-2 virus, an enveloped RNA of the coronavirus family. The advancement in molecular technology and biochemistry has accelerated the development of diagnostic reagents and assays. Much attention has been focused on the S protein, but the high mutation rate in this region could lead to false negative results. Thus, a better target protein for diagnostic application is needed for accurate detection. Method(s): Nucleotide sequences encoded for membrane (M) glycoprotein gene region of SARS-CoV-2 from Malaysian isolates were extracted from GISAID, aligned, and selected accordingly. The DNA plasmid was commercially synthesized with codon optimization for Escherichia coli (E. coli), and the presence of the M gene was confirmed by PCR. The plasmid was then transformed into E. coli. Later, the expression of M glycoprotein was induced, separated on an SDS-PAGE gel, and transferred onto a nitrocellulose membrane, followed by immunostaining. Finding(s): The analysis of the M glycoprotein against the Omicron strains demonstrated that the amino acid is conserved (99.5%). The M glycoprotein was successfully expressed and detected with antibodies from SARS-CoV-2 infected patients at ~26 kDa. The protein is currently upscale for the generation of monoclonal Ab (Mab). Discussion(s): The M protein of SARS-CoV-2 is more conserved among the virus and also has been reported to confer antigenic properties. Selection of M protein perhaps a better option compared to current detection assays that use spike (S) protein, which could lead to false negative results, as this gene region particularly the ribosome-binding domain (RBD) rapidly undergoes mutations. The utilization of M protein potentially improves negative predictive value (NPV) of the diagnostic test. Conclusion(s): Further development of diagnostic reagents is needed to improve the assay's specificity. The newly developed M protein and the MAb can be used to generate a more accurate viral detection assay.Copyright © 2023

Isolation and Characterization of Protein Complexes of Overexpressed Human Serum Amyloid A from Cytokines-Induced Hepg2 Cells

Serum Amyloid A (SAA) is an apolipoprotein found in the serum of many vertebrate species and is associated with the acute-phase reaction in the body with expression levels reaching up to a 1000-fold increase. The loss of its alpha-helix conformation during its expression peak is directly linked to secondary amyloidosis. Recent studies have been suggested to play a role in cholesterol and HDL metabolism, retinol transport and tumor pathogenesis. Moreover, high SAA concentration in blood have been correlated with severe symptoms or death in patients with COVID-19. However, how this protein is involved in so many diseases is uncertain or not completely understood. Therefore, the purpose of this research is to determine which protein-protein interactions with SAA occur in human cells, and to predict its biochemical role based on new discovered complexes. Two major isoforms overexpressed during an acutephase reaction, human SAA1 and SAA2, are the focus of this study. Both are primarily produced in hepatocytes. HepG2 cells were cultured and induced with interleukin-1b, interleukin-6, LPS and retinol. Protein complexes associated with SAA will be isolated through a co-Immunoprecipitation technique, resolved by SDS-PAGE, and characterized by mass spectrometry. Our hypothesis focus on those protein complexes with SAA to explain how this protein lead other undiscovered metabolic pathways involved in both cellular and survival regulation. Special thanks to The Science and Technology Competency & Education Core (Stce) for Undergraduate and Graduate Junior Research Associates Working Program from the Puerto Rico IDeA Network Biomedical Research Excellence for funding part of this research.Copyright © 2023 The American Society for Biochemistry and Molecular Biology, Inc.

Protease Activity in the Excretory-Secretory Products of Nymphal Stage of Linguatula Serrata: First Detection of a Metalloprotease

The aim of this study was to evaluate the presence of proteases and determine the main protease present in the excretory-secretory products (ESPs) from nymphal stage of Linguatula serrata. Infected mesenteric lymph nodes of goats were collected from Tabriz slaughterhouse, northwestern Iran. Recovered Linguatula serrata nymphs were immersed in culture medium (MEM), then ESPs were collected and protease activity in presence of specific inhibitors was assayed. Protease enzyme was fur-ther characterised by SDS-PAGE. The results of this study showed that the main protease in the ESPs from the nymphal stage of L. serrata was a metalloprotease that was resistant to heat. In conclusion, these data show that a major protease secreted by the larval stage of L. serrata exhibited properties that may play a role in the pathogenesis of L. serrata nymphs.Copyright © 2023, Trakia University. All rights reserved.

Production and characterization of lentivirus vector-based SARS-CoV-2 pseudoviruses with dual reporters: Evaluation of anti-SARS-CoV-2 viral effect of Korean red ginseng.

Background: Pseudotyped virus systems that incorporate viral proteins have been widely employed for the rapid determination of the effectiveness and neutralizing activity of drug and vaccine candidates in biosafety level 2 facilities. We report an efficient method for producing severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) pseudovirus with dual luciferase and fluorescent protein reporters. Moreover, using the established method, we also aimed to investigate whether Korean red ginseng (KRG), a valuable Korean herbal medicine, can attenuate infectivity of the pseudotyped virus. Methods: A pseudovirus of SARS-CoV-2 (SARS-2pv) was constructed and efficiently produced using lentivirus vector systems available in the public domain by the introduction of critical mutations in the cytoplasmic tail of the spike protein. KRG extract was dose-dependently treated to Calu-3 cells during SARS2-pv treatment to evaluate the protective activity against SARS-CoV-2. Results: The use of Calu-3 cells or the expression of angiotensin-converting enzyme 2 (ACE2) in HEK293T cells enabled SARS-2pv infection of host cells. Coexpression of transmembrane protease serine subtype 2 (TMPRSS2), which is the activator of spike protein, with ACE2 dramatically elevated luciferase activity, confirming the importance of the TMPRSS2-mediated pathway during SARS-CoV-2 entry. Our pseudovirus assay also revealed that KRG elicited resistance to SARS-CoV-2 infection in lung cells, suggesting its beneficial health effect. Conclusion: The method demonstrated the production of SARS-2pv for the analysis of vaccine or drug candidates. When KRG was assessed by the method, it protected host cells from coronavirus infection. Further studies will be followed for demonstrating this potential benefit.

PURIFICATION OF ANTI-RBD ANTIBODIES OBTAINED FROM LLAMA (Lama glama) FOR POTENTIAL COVID-19 THERAPY

Despite worldwide efforts to develop different treatments for SARS-CoV-2 COVID-19, the situation remains critical, requiring rapid and effective strategies. In this regard, antibodies (Ab) have demonstrated clinical potential. Among them, camelid nanoAb (VHH) arise as a possible alternative, as they recognize epitopes which are inaccessible to conventional Ab. Further advantages of VHH are their small size, high solubility, high stability, and resistance to low pH. The aim of this work is to describe a purification scheme of different isotypes of anti-SARS-CoV-2 immunoglobulin G (IgG) produced after immunizing two llamas (Lama glama). To achieve this, plasma was injected into an affinity chromatographic column (Protein G), and the resulting fractions were analyzed by SDS-PAGE under non-reducing conditions. The anti-RBD titers were determined by an “in house” ELISA, reaching titers of 52000 and 13000 for IgG1 and IgG3 fractions, respectively. Subsequently, an affinity column (HiTrap NHS-activated) was prepared to separate monospecific anti-RBD polyclonal Ab. RBD produced in our laboratory was covalently coupled to this column, achieving a coupling efficiency of 97%. Different isotypes of monospecific anti-RBD Ab (IgG1: 140 kDa and IgG3: 95 kDa) were obtained. IgG3 represent the starting point for obtaining VHH and/or evaluating their potential use as a therapeutic or preventive alternative, which represents a notable regional contribution in the fight against COVID-19.

Optimization strategies for improving soluble expression of sars-cov-2 s1 protein using sumo-fusion technology

BACKGROUND AND AIM: E. coli are widely used for recombinant protein development, due to its low cost, ease of manipulation, and availability of well established molecular tools and techniques. Due to a lack of sophisticated machinery to undertake posttranslational modifications, the E. coli bacterial culture is limited in its ability to express more complex proteins, resulting in low solubility of the protein of interest that is generated as inclusion bodies. Although we were able to produce the recombinant SARS-CoV-2-S1 protein at high expression levels in our earlier investigation, we were also able to obtain nearly the whole protein as inclusion body. To overcome this problem, different solubility strategies have been tried. In this study, we developed an E.coli expression strategy based on the expression of the S1 protein as a fusion of SUMO fusion protein. METHODS: The DNA sequence of S1 protein was cloned into the pET SUMO expression vector, resulting in a construct expressing a N-terminal tag SUMO fusion protein. To achieve the high-level expression of S1, small scale expression conditions were optimized in E. coli BL21 (DE3) containing pET SUMO-S1 with different induction temperatures, times and IPTG concentrations. Additionally, different medium was also tested for the expression of S1 protein. For each parameter, solubility and expression of cell lysates from uninduced and induced cultures, plus the soluble and insoluble fractions from induced cultures were analyzed by SDS-PAGE and Western Blot. RESULTS: SDS-PAGE and Western Blot analysis showed the presence of a ∼83 kDa recombinant fusion protein. The maximum level of expression of the recombinant protein was observed at 30 , 4 h after induction with 0,55 mM IPTG. CONCLUSIONS: This study showed that the use of SUMO fusion tag partially increases the production of S1 protein in the form of soluble fractions and optimization studies continue.

PURIFICATION of SPECIFIC ANTIBODIES AGAINST SARS-COV-2 PROTEIN NP USING the FasTAG® SYSTEM

The SARS-CoV-2 coronavirus, which causes respiratory syndrome COVID-19, has a protein nucleocapsid that envelops the viral ssRNA. The main protein of the nucleocapsid is the Np protein, which presents limited homology with nucleoproteins of other coronaviruses and therefore turns out to be an attractive antigen for the development of specific anti-Np antibodies. These antibodies can be used for the development of diagnostic systems that allow the detection of the viral antigen in infected individuals from saliva samples. In this context, our group has developed a labelling system called FasTAG®, which allows the immobilization of recombinant proteins on the surface of Gram+ formaldehyde inactivated bacteria. In this system, the recombinant proteins expressed in heterologous systems are fused to the C-terminal domain of S-Layer proteins of Lactobacillus sp. Then, the intrinsic affinity this domain possesses for the membranes of Gram+ bacteria is used for the immobilization of the recombinant proteins of interest. In this way, it is possible to purify specific antibodies against an antigen of interest. Based on the above, the objective of this work was to evaluate the functionality of the FasTAG® system to purify specific anti-Np antibodies. For this, the recombinant protein Np-FasTAG® was incubated for 12 hours at 4 °C with a matrix made up of B. subtilis inactivated with 3% formaldehyde. Next, for the optimization of the protein fixation process to the matrix, a compound factorial design was carried out, the variables of which were: formaldehyde concentration (0.5-1.5-2.5% v/v) and time of incubation (15-30-45 minutes). The optimal condition was determined as the one that minimizes the detachment of the Np protein and maximizes the detachment of the specific antibodies. Turning out to be the optimal condition for the elaboration of the affinity matrix 2.5% v/v of formaldehyde and 15 minutes. Then, in order to evaluate the application of the affinity matrix in the purification of specific antibodies, it was incubated for 1 hour with polyclonal antibodies obtained from chicken egg yolks and the serum of goats immunized with the Np antigen. Next, to study the elution conditions of the antibodies, a compound factorial design was performed using variables: pH, time, and SDS concentration. The best elution condition was obtained for pH 10.5 and 15 minutes. Subsequently, the purified antibodies were evaluated by SDS-PAGE and ELISA. As a result, it was possible to purify 3.5 μg of anti-Np IgG and 3.1 μg of anti-Np IgY per mg of resin. Finally, the set of experiments carried out here demonstrate the potential and functionality of this system for the purification of specific anti-Np antibodies and their use for diagnostic purposes.

The dynamic nature of the coronavirus receptor, angiotensin-converting enzyme 2 (ACE2) in differentiating airway epithelia.

Once inhaled, SARS-CoV-2 particles enter respiratory ciliated cells by interacting with angiotensin converting enzyme 2 (ACE2). Understanding the nature of ACE2 within airway tissue has become a recent focus particularly in light of the COVID-19 pandemic. Airway mucociliary tissue was generated in-vitro using primary human nasal epithelial cells and the air-liquid interface (ALI) model of differentiation. Using ALI tissue, three distinct transcript variants of ACE2 were identified. One transcript encodes the documented full-length ACE2 protein. The other two transcripts are unique truncated isoforms, that until recently had only been predicted to exist via sequence analysis software. Quantitative PCR revealed that all three transcript variants are expressed throughout differentiation of airway mucociliary epithelia. Immunofluorescence analysis of individual ACE2 protein isoforms exogenously expressed in cell-lines revealed similar abilities to localize in the plasma membrane and interact with the SARS CoV 2 spike receptor binding domain. Immunohistochemistry on differentiated ALI tissue using antibodies to either the N-term or C-term of ACE2 revealed both overlapping and distinct signals in cells, most notably only the ACE2 C-term antibody displayed plasma-membrane localization. We also demonstrate that ACE2 protein shedding is different in ALI Tissue compared to ACE2-transfected cell lines, and that ACE2 is released from both the apical and basal surfaces of ALI tissue. Together, our data highlights various facets of ACE2 transcripts and protein in airway mucociliary tissue that may represent variables which impact an individual's susceptibility to SARS-CoV-2 infection, or the severity of Covid-19.

Development of Sars-Cov-2 Antigen Detection Kit Based on Immunoglobulin Y (Igy) Using Surface Plasmon Resonance (Spr)

SAR S disease reappeared at the end of 2019 with a new name as Coronavirus Disease 2019 (COVID-19) caused by a new virus called SARS-CoV-2. This virus has spread throughout the world until recently and caused massive deaths and losses. The nucleic acid test in the form of real-time reverse transcriptase-polymerase chain reaction (RT-PCR) is very important to diagnose COVID-19 in patients, but this method has several drawbacks such as operators who have to be trained, the diagnosis results appear in a relatively long time, and the examination price relatively expensive. This research was conducted to produce immunoglobulin Y (IgY) extracted from chicken egg yolk targeting the S-protein receptor-binding domain (RBD) on SARSCoV- 2 as a component of the surface plasmon resonance (SPR) SARS-CoV-2 antigen detection kit. This research was started by extracting IgY from hyperimmune chicken egg yolks with the polyethylene glycol (PEG) precipitation method and continued with dialysis. The extracted IgY was further purified using thiophilic adsorption chromatography and concentrated by using Amicon® Ultra-15 ultrafiltration. The IgY activity against SARS-CoV-2 RBD was tested qualitatively using the agar gel precipitation test (AGPT) technique and the total protein content was determined using the Lowry method. IgY was tested for its affinity against SARS-CoV-2 RBD using SPR. The IgY concentration obtained was 11 mg/mL. The AGPT result showed the presence of IgY activity against SAR S-CoV-2 RBD isolated from egg yolk and chicken serum after 8 weeks after the first vaccination of chickens. The SDS-PAGE results showed a very clear band of IgY characters. The obtained IgY showed adequate interaction with commercial SARS-CoV-2 RBD on an SPR device. The purified IgY was able to bind with protein-S RBD and showed a fairly good affinity for the SARS-CoV-2 antigen sample. The results of these observations indicate that IgY anti-S-protein SARS-CoV-2 can be produced and purified from chicken egg yolk and can be used as a diagnostic component to detect SARS-CoV-2 antigen, especially on SPR.

Antimicrobial Photodynamic Disinfection (APDT) Destroys SARS-COV-2 Receptor Binding Domains and Spike Protein Independent of Viral Variant

Introduction: We previously reported on the elimination of the RNA signature of laboratory strains as well as wild-type SARS-CoV-2 using a photodynamic disinfection technique. This report extends the work to destruction of receptor binding domains, spike protein and nucleocapsid protein of major SARS-CoV-2 variants including the dominant Delta variant. Objectives: The objective of this work was to evaluate effect of a 2-min cycle of aPDT on receptor binding domains, spike protein and nucleocapsid protein of SARS-CoV-2. Methods: Spike glycoprotein receptor binding domain proteins from SARS-Related Coronavirus 2 included recombinant NR-54004 (United Kingdom Variant), NR-54005 (South African Variant), and NR-52366 (Wuhun-Hu-1 Variant) (BEI Resources, NIAID, ATCC). Recombinant spike proteins included B.1.1.7 Spike Protein, United Kingdom Variant (10748-CV-100), B.1.617 Spike Protein, Indian (Delta) Variant (10861-CV-100), B.1.351 Spike Protein, South African Variant (10777-CV-100), P.1 Spike Protein, Brazilian Variant (10795-CV-100) (all from R&D Systems, Inc.), and the stabilized spike glycoprotein, Wuhun-Hu-1 Variant (NR-52397). The SARS-CoV-2 nucleocapsid protein (NR55344, Avi-Histag, Biotin-Labeled, BEI Resources, NIAID, ATCC) was also tested for susceptibility to damage. aPDT was carried out by exposing each viral component to a photosensitizer formulation containing 320 uM methylene blue in an aqueous adjuvant, immediately followed by 36 J/cm2 (120 s) of non-thermal laser light at 664 nm (Steriwave® aPDT system, Ondine Biomedical Inc., Vancouver, B.C.). Illumination was conducted in a custom thin-film cell replicating the anterior nasal architecture. Control solutions were identically treated but without light exposure. 50 ul samples of treated and control solutions were evaluated by SDSPAGE using SYPRO Ruby Protein Gel Stain. Results: SDS-PAGE evaluation of all treated RBD, spike and SARSCoV-2 nucleocapsid protein samples showed no detectable protein remaining after 2 min exposure to photodynamic disinfection treatment. All no-light control samples remained unaffected. Conclusion: A 2-min photodynamic disinfection procedure was demonstrated to destroy RBD's, spike protein and nucleocapsid protein of major SARS-CoV-2 viral variants in circulation, expanding on previous work evaluating RNA damage in this virus. This outcome supports the use of aPDT as a potential SARS-CoV-2 suppression technique.

Neutralization of SARS-CoV-2 pseudovirus using ACE2-engineered extracellular vesicles.

The spread of coronavirus disease 2019 (COVID-19) throughout the world has resulted in stressful healthcare burdens and global health crises. Developing an effective measure to protect people from infection is an urgent need. The blockage of interaction between angiotensin-converting enzyme 2 (ACE2) and S protein is considered an essential target for anti-severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) drugs. A full-length ACE2 protein could be a potential drug to block early entry of SARS-CoV-2 into host cells. In this study, a therapeutic strategy was developed by using extracellular vesicles (EVs) with decoy receptor ACE2 for neutralization of SARS-CoV-2. The EVs embedded with engineered ACE2 (EVs-ACE2) were prepared; the EVs-ACE2 were derived from an engineered cell line with stable ACE2 expression. The potential effect of the EVs-ACE2 on anti-SARS-CoV-2 was demonstrated by both in vitro and in vivo neutralization experiments using the pseudovirus with the S protein (S-pseudovirus). EVs-ACE2 can inhibit the infection of S-pseudovirus in various cells, and importantly, the mice treated with intranasal administration of EVs-ACE2 can suppress the entry of S-pseudovirus into the mucosal epithelium. Therefore, the intranasal EVs-ACE2 could be a preventive medicine to protect from SARS-CoV-2 infection. This EVs-based strategy offers a potential route to COVID-19 drug development.