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In eukaryotic cells, the endoplasmic reticulum is particularly important in post-translational modification of proteins before they are released extracellularly or sent to another endomembrane system. The correct three-dimensional folding of most proteins occurs in the ER lumen, which has an oxidative environment that is essential for the formation of disulfide bridges, which are important in maintaining protein structure. The ER is a versatile organelle that ensures the correct structure of proteins and is essential in the synthesis of lipids and sterols, in addition to offering support in the maintenance of intracellular calcium. Consequently, the cells needed to respond to demands caused by physiological conditions and pathological disturbances in the organelle homeostasis, leading to proper functioning of the cell or even programmed cell death. Disturbances to the ER function trigger a response to the accumulation of unfolded or misfolded proteins, known as the unfolded protein response. Such disturbances include abiotic stress, pharmacological agents, and intracellular pathogens, such as viruses. When misfolded proteins accumulate in the ER, they can undergo ubiquitination and proteasomal degradation through components of the ER-associated degradation system. Once a prolonged activity of the UPR pathway occurs, indicating that homeostasis cannot be reestablished, components of this pathway induce cell death by apoptosis. Here, we discuss how viruses have evolved ways to counteract UPR responses to maximize replication. This evolutionary viral ability is important to understand cell pathology and should be taken into account when designing therapeutic interventions and vaccines. [ABSTRACT FROM AUTHOR]

Brazil was considered one of the emerging epicenters of the coronavirus pandemic in 2021, experiencing over 3000 daily deaths caused by the virus at the peak of the second wave. In total, the country had more than 20.8 million confirmed cases of COVID-19, including over 582,764 fatalities. A set of emerging variants arose in the country, some of them posing new challenges for COVID-19 control. The goal of this study was to describe mutational events across samples from Brazilian SARS-CoV-2 sequences publicly obtainable on Global Initiative on Sharing Avian Influenza Data-EpiCoV (GISAID-EpiCoV) platform and to generate indexes of new mutations by each genome. A total of 16,953 SARS-CoV-2 genomes were obtained, which were not proportionally representative of the five Brazilian geographical regions. A comparative sequence analysis was conducted to identify common mutations located at 42 positions of the genome (38 were in coding regions, whereas two were in 5′ and two in 3′ UTR). Moreover, 11 were synonymous variants, 27 were missense variants, and more than 44.4% were located in the spike gene. Across the total of single nucleotide variations (SNVs) identified, 32 were found in genomes obtained from all five Brazilian regions. While a high genomic diversity has been reported in Europe given the large number of sequenced genomes, Africa has demonstrated high potential for new variants. In South America, Brazil, and Chile, rates have been similar to those found in South Africa and India, providing enough "space" for new mutations to arise. Genomic surveillance is the central key to identifying the emerging variants of SARS-CoV-2 in Brazil and has shown that the country is one of the "hotspots" in the generation of new variants. [ABSTRACT FROM AUTHOR]

Objective: Previous studies indicated that face masks reduce the probability of infection by SARS-CoV-2 but did not examine the relationship between SARS-CoV-2 viral load and mask usage. This study analyzed this relationship., Methods: This cross-sectional study evaluated patients admitted to a public Emergency Care Unit in Belo Horizonte, MG, Brazil, between October 2020 and March 2021. Convenience samples were recruited during the study period. Adult patients with COVID-19 symptoms were invited to participate after being examined by a physician according to the Emergency Care Unit routine. This study included 441 adults with mild symptoms diagnosed with COVID-19 via RT-PCR, who were tested until the 14th day after symptom onset. Participants were interviewed about mask usage, oropharyngeal swabs were collected, and the SARS-CoV-2 viral load was measured using RT-PCR. The difference between the SARS-CoV-2 viral load in the groups of individuals who regularly used and did not use masks was subjected to a hypothesis test., Results: Of the patients who had swabs collected 1-5 days after symptom onset, 64.9% of those not using masks regularly and 45.5% of those using masks regularly presented a high SARS-CoV-2 viral load. This difference was statistically significant (p=0.0073). Considering only the patients who had swabs collected 4-8 days after symptom onset, 44.1% of those not using masks regularly and 30.8% of those using masks regularly presented a high SARS-CoV-2 viral load; this difference was statistically significant (p=0.0364)., Conclusion: When people who regularly wear a face mask contract COVID-19, they have a significantly lower probability of having a high viral load of SARS-CoV-2 compared to those who do not regularly wear masks.

Objective: To show the feasibility of the combined use of self-collected nasopharyngeal swab and pool testing to detect SARS-CoV-2 in epidemiological surveys., Methods: This experience included a sample of 154 students at the Universidade Federal de Minas Gerais, who performed self-collected nasopharyngeal swab in individual cabins and without supervision. The molecular test was performed using the pool testing technique., Results: It took each person 5 minutes to collect the sample. An analysis was performed to detect endogenous RNA in 40 samples. The results showed that there were no failures resulting from self-collection. None of the pools detected the presence of viral RNA. The cost of molecular testing (RT-PCR), by pool testing, with samples obtained by self-collection was about ten times lower than the usual methods., Conclusion: The strategies that were investigated proved to be economically feasible and valid for the research on SARS-CoV-2 in epidemiological surveys.