ABSTRACT
COVID-19, caused by the novel SARS-CoV-2 virus, poses major challenges for global public health. The detection of antibodies in blood serum is one of the important methods for diagnostics of COVID-19 patients. The main aim was to study the dynamics of the appearance of neutralizing antibodies and antibodies to the SARS-CoV-2 proteins in COVID-19 patients sera. Material and methods. The blood sera of four groups of people were studied: "intact" donors (blood sera were collected in 2016-2019);patients with a laboratory-confirmed diagnosis of acute respiratory viral infection;patients with influenza (antibodies to the influenza virus have been identified) and patients with a PCR confirmed diagnosis of COVID-19. Blood sera were analyzed in ELISA with commercial kits for detection of IgG to SARS-CoV-2 (N, S) proteins and total antibodies to RBD of protein S and in neutralization test (NT). Results and discussion. Antibodies to SARS-CoV-2 were not detected in paired blood sera of people from groups 1-3 by ELISA and NT. At the time of hospitalization of patients with COVID-19 in the sera of 12 (19%) patients antibodies to SARS-CoV-2 were absent when they were determined by NT and ELISA. In blood sera taken 4-9 days after hospitalization, neutralizing antibodies and antibodies to at least one viral protein were detected in ELISA. Conclusion. At the time of hospitalization, the overwhelming majority of patients had a humoral immune response to the SARS-CoV-2. In the dynamics of observation, the levels of antibodies to SARS-CoV-2 proteins increased, to a greater extent to RBD.Copyright © 2022 Geotar Media Publishing Group
ABSTRACT
Background: The health emergency caused by the COVID-19 pandemic has evidenced that the frequency of spillover episodes of viruses infecting bats to other species, including humans, has significantly increased compared to previous decades. Besides SARS-CoV-2, six other human coronaviruses (NL63, 229E, OC43, HKU1, SARS-CoV and MERS-CoV) emerged in the 20th and 21st century, most likely because of cross-species transmission events from bats. While many of these coronaviruses cause mild respiratory infections, MERS-CoV, SARS-CoV and SARS-CoV-2 can cause severe respiratory distress, particularly in immunocompromised individuals. However, unlike SARS-CoV and MERS-CoV, SARS-CoV-2 is highly contagious, very stable, with many person-to-person transmissions, which can occur even before individuals exhibit any symptoms. While vaccines are readily available, the emergence of new SARS-CoV-2 variants along with the increasing incidence of individuals developing long COVID urge to develop antivirals specific to treat COVID-19. To reach this goal, we need to have a working knowledge of the host-SARS-CoV-2 interactions to identify targets for therapeutic intervention. Method(s): Following that rationale, we focused on understanding how SARSCoV- 2 generates replication organelles (ROs). All coronaviruses need to remodel cellular membranes to create these structures to allow the active replication and transcription of their genome. Due to their relevance for virus replication, disabling RO formation represents a promising strategy to fight SARS-CoV-2. However, the biogenesis mechanism, the origin, and type of these replication organelles are still a major focus of debate. To identify the cellular membranes that SARS-CoV-2 uses to generate ROs we used multiple cell lines and primary cells that were evaluated by fluorescence microscopy, genetic engineering, compounds that specifically inhibit cellular processes, and immunoprecipitation assays to validate protein-protein interactions. We also used RT-qPCR to assess viral genome replication. Result(s): SARS-CoV-2 uses the viral protein NSP6 to remodel endosomal membranes juxtaposed to the ER to generate replication organelles. Specifically, the virus depends on Clathrin, COPB1, and Rab5 for efficient SARSCoV- 2 RNA synthesis. Conclusion(s): Uncovering the origins and mechanism(s) by which SARS-CoV-2 assembles ROs opens new avenues to develop strategies to interfere with RO biogenesis and halt virus replication.
ABSTRACT
Coronaviruses have emerged as important agents of human infection. SARS-CoV-2, the causative agent of COVID-19, has triggered a global pandemic with devastating consequences. The understanding of fundamental aspects of these viruses is of extreme importance. Fast vaccine development has been a crucial factor in preventing serious disease, but the fast-paced emergence of new variants raises many problems. Viral non-structural proteins are fundamental for viral replication. SARS-CoV-2 nsp16 is a 20-O-methyltransferase with a pivotal role in Interferon antagonism. Nsp16 methylates viral RNA to mimic the host mRNA and then the cell stops recognizing it as foreign. This activity is stimulated by the interaction with nsp10. This protein also acts as a co-factor for the exoribonucleolytic activity of nsp14. Nsp14 also has significant anti-interferon importance that stems from its 2 distinct activities: the N-terminal 3'-to-5' exoribonuclease (ExoN) and a C-terminal N7-methyltransferase (N7-MTase). Unlike Spike proteins, these nsp10, nsp14, and nsp16 are highly conserved among viral variants. In this work, we are studying them and finding inhibitors in order to develop new therapies. Nsp10 is the prime target of our focus since it is the central player in the regulation of both nsp14 and nsp16.
ABSTRACT
The recently identified 2019 novel coronaviruses (2019-nCoV) has caused extra-human infections. 2019-nCoV identified a global threat that is causing an outbreak of unusual viral pneumonia in patients with severe acute respiratory syndrome (SARS)-coronaviruses 2 (SARS-CoV-2). Considering the relatively high identity of the receptor-binding domain (RBD) in 2019-nCoV and SARS-CoV, it is urgent to assess the cross-reactivity of anti-SARS-CoV antibodies with 2019-nCoV spike protein, which could have important implications for rapid development of vaccines and therapeutic antibodies against 2019-nCoV. The zinc metallopeptidase angiotensin-converting enzyme 2 (ACE2) is the only known human homolog of the key regulator of blood pressure ACE. ACE2 also serves as the cellular entry point for the SARS virus, therefore, a prime target for pharmacological intervention. SARS-CoV-2 uses the SARS-CoV receptor for entry and the serine protease transmembrane protease serine 2 for spike (S) protein priming. That it is still necessary to develop novel mAbs that could bind specifically to 2019-nCoV RBD. Cell entry of coronaviruses depends on the binding of the viral S proteins to cellular receptors and S protein priming by host cell proteases. A transmembrane protease serine 2 inhibitor approved for clinical use blocked entry and might constitute a treatment option. Our results reveal important commonalities between SARS-CoV-2 and SARS-CoV infection and identify a potential target for antiviral intervention. This review will help understand the biology and potential risk of CoVs that exist in richness in wildlife such as bats. We provide a brief introduction to the pathogenesis of SARS-CoV and Middle East respiratory syndrome-CoV and interaction between the RBD of coronavirus spike protein and ACE2.
ABSTRACT
Glycans are among the most important cell molecular components. However, given their structural diversity, their functions have not been fully explored. Glycosylation is a vital post-translational modification for various proteins. Many bacteria and viruses rely on N-linked and O-linked glycosylation to perform critical biological functions. The diverse functions of glycosylation on viral proteins during viral infections, including Dengue, Zika, influenza, and human immunodeficiency viruses as well as coronaviruses have been reported. N-linked glycosylation is the most common form of protein modification, and it modulates folding, transportation and receptor binding. Compared to N-linked glycosylation, the functions of O-linked viral protein glycosylation have not been comprehensively evaluated. In this review, we summarize findings on viral protein glycosylation, with particular attention to studies on N-linked glycosylation in viral life cycles. This review informs the development of virus-specific vaccines or inhibitors.