Cellular stress and SARS-CoV-2

Background: SARS-CoV-2, the etiological agent responsible for COVID-19, is an RNA virus belonging to the Coronaviridae family. During the virus replication, viral components interact with the cellular machinery, inducing alterations in cell physiology, which contributes to viral pathogenesis. Method(s): A bibliographical research about cellular stress and SARS-CoV-2 was performed at NCBI/Pubmed. Result(s): In response to the infection, signaling pathways are activated in the host cell, the goal of these pathways being to restore homeostasis. If homeostasis is not recovered, the signaling leads to cell death activation. Among the best-characterized signaling pathways, the cellular stress pathways such as oxidative stress, UPR, and autophagy stand out, which are evolutionarily conserved and are also interconnected with each other. There is strong theoretical and experimental evidence of various interactions of some components of these pathways with different viral proteins of coronavirus, and some studies with SARS-CoV-2 have already been performed. In this review, we highlight some of the cellular pathways-virus characterized to date. Conclusion(s): The cellular pathways and their relationship to viral infections remains unclear. The study of these relationships might constitute an important target for new research and the development of antiviral therapies. Copyright © 2021, Revista Salus. All rights reserved.

Sub-lineages of the Omicron variant of SARS-CoV-2: characteristic mutations and their relation to epidemiological behavior

By the end of 2021, the Omicron variant of SARS-CoV-2, the coronavirus responsible for COVID-19, emerges, causing immediate concern, due to the explosive increase in cases in South Africa and a large number of mutations. This study describes the characteristic mutations of the Omicron variant in the Spike protein, and the behavior of the successive epidemic waves associated to the sub-lineages throughout the world. The mutations in the Spike protein described are related to the virus ability to evade the protec-tion elicited by current vaccines, as well as with possible reduced susceptibility to host proteases for priming of the fusion process, and how this might be related to changes in tropism, a replication enhanced in nasal epithelial cells, and reduced in pulmonary tissue;traits probably associated with the apparent reduced severity of Omicron compared to other variants. © 2022, Instituto de Investigaciones Clinicas. All rights reserved.

Detection of the Omicron variant of SARS-CoV-2 by restriction analysis targeting the mutations K417N and N440K of the spike protein

By the end of 2021, the Omicron variant of concern (VOC) emerges in South Africa. This variant caused immediate concern, due to the explosive increase in cases associated with it and the large number of mutations it exhibits. In this study, the restriction sites that allow detecting the mutations K417N and N440K in the Spike gene are described. This analysis al-lows us to propose a rapid method for the identification of cases infected with the Omicron variant. We show that the proposed methodology can contribute to provide more information on the prevalence and rapid detection of cases of this new VOC. © 2022, Instituto de Investigaciones Clinicas. All rights reserved.

Biology and evolution of the coronavirus that causes COVID-19

The new coronavirus that causes COVID-19 is called SARS-CoV-2 and belongs to the subgenus Sarbecovirus, like its predecessor SARS-CoV. Bats appear to be the hosts of the ancestral viruses that originated these viruses, through recombination with the virus of an intermediate animal, which might be the pangolin. The virus interacts with the ACE2 receptor (angiotensin converting enzyme 2) and enters the cell by the endocytic pathway, through an early or late endosome. Viral RNA serves as messenger RNA for the translation of the first reading frame and the rest of the messenger RNAs are produced by discontinuous transcription. This peculiarity confers to this viral family a high frequency of recombination, which is associated to the high frequency of species jumping. Viruses belonging to the order Nidovirales are the only known RNA viruses with a polymerase with proof correction capacity;therefore their mutation rate is reduced. However, these genomes appear to be susceptible to be deaminated by cellular enzymes. All these mechanisms of generation of diversity leads to the existence of lineages, including those with the D614G mutation in the spike associated with a higher transmissibility. However, mutations associated with greater severity are not known to date. Just as there are different viral variants, the clinical manifestation of the disease is also highly variable. Some genetic, physiological and metabolic factors are being known that could be determining a more severe clinical presentations, often associated with the immunopathology of this disease.