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The COVID-19 pandemic resulted from the global spread of the severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2). Since its first appearance in 2019, new SARS-CoV-2 variants of concern (VOCs) have emerged frequently, changing the infection's dynamic. SARS-CoV-2 infects cells via two distinct entry routes; receptor-mediated endocytosis or membrane fusion, depending on the absence or presence of transmembrane serine protease 2 (TMPRSS2), respectively. In laboratory conditions, the Omicron SARS-CoV-2 strain inefficiently infects cells predominantly via endocytosis and is phenotypically characterized by decreased syncytia formation compared to the earlier Delta variant. Thus, it is important to characterize Omicron's unique mutations and their phenotypic manifestations. Here, by utilizing SARS-CoV-2 pseudovirions, we report that the specific Omicron Spike F375 residue decreases infectivity, and its conversion to the Delta S375 sequence significantly increases Omicron infectivity. Further, we identified that residue Y655 decreases Omicron's TMPRSS2 dependency and entry via membrane fusion. The Y655H, K764N, K856N and K969N Omicron revertant mutations, bearing the Delta variant sequence, increased the cytopathic effect of cell–cell fusion, suggesting these Omicron-specific residues reduced the severity of SARS-CoV-2. This study of the correlation of the mutational profile with the phenotypic outcome should sensitize our alertness towards emerging VOCs. [ABSTRACT FROM AUTHOR]

The article discusses the emergence of the SARS-CoV-2 KP.2 variant, which is a descendant of the BA.2.86 variant. While the KP.2 variant has shown an increase in cases, there is no evidence suggesting that it is a significantly concerning new variant. The article provides information on the global prevalence of the KP.2 variant, highlighting regions where it has been detected and its relative prevalence in different countries. The KP.2 variant carries mutations of interest, including K417N, S477N, N501Y, and P681R, which may pose potential risks. Additionally, it shares the E484K mutation, which has been associated with the ability to evade immune responses. However, the lasting immunity conferred by natural immune responses to these mutations has not been explicitly documented. The KP.2 variant of SARS-CoV-2, also known as the Omicron variant, carries three additional mutations in the spike protein genes compared to its ancestor, the JN.1 variant. These mutations, R346T, F456L, and V1104L, have been observed in other Omicron subvariants and are associated with increased transmission and evasion of neutralizing antibodies. The F456L mutation, in particular, enhances the spike protein's affinity for the ACE2 receptor, allowing the virus to better evade immune responses. The V1104L mutation, located within a T cell epitope, may enhance protein stability. However, it is [Extracted from the article]

VOC Omicron induce "common cold symptoms" and sore throat more often than wild-type and VOC Delta infections (Figures 2 and 3). Presentation of airway and general symptoms in COVID-19 caused by dominant SARS-CoV-2 variants: A follow-up on ARIA consensus GLO:1X5/01nov22:all15416-fig-0001.jpg PHOTO (COLOR): 1 Expected symptom intensity on analogue scale (0: no symptom and 10: strongest symptoms) for wild-type and virus variants of SARS-CoV-2, rated by ARIA specialists. Symptom groups A/B/C/D are explained in the main text and referred to Figure 2 gl Significantly differing symptoms were grouped concerning common cold and sore throat, chemosensory, bronchial and pulmonary, as well as systemic (Figure 2). [Extracted from the article]

We aimed to assess the feasibility of TESTA'T COVID strategy among healthcare and education professionals.in Spain during the peak of the 6th wave caused by Omicron variant. Kits were ordered online and sent by mail, participants answered an online acceptability/usability survey and uploaded the picture of results. 492 participants ordered a test, 304 uploaded the picture (61.8%). Eighteen positive cases were detected (5.9%). 92.2% were satisfied/very satisfied with the intervention; and 92.5% found performing the test easy/very easy. We demonstrated that implementing online COVID-19 self-testing in schools and healthcare settings in Spain is feasible. [ABSTRACT FROM AUTHOR]