Emergence of New SARS-CoV2 Omicron Variants after the Change of Surveillance and Control Strategy.

In January 2022, there was a global and rapid surge of the Omicron variant of SARS-CoV-2 related to more transmission. This coincided with an increase in the incidence in Asturias, a region where rapid diagnosis and containment measures had limited the circulation of variants. METHODS: From January to June 2022, 34,591 variants were determined by the SNP method. From them, 445 were characterized by the WGS method and classified following pangolin program and phylogenic analysis. RESULTS: The Omicron variant went from being detected in 2438 (78%) samples in the first week of January 2021 to 4074 (98%) in the third week, according to the SNP method. Using the WGS method, 159 BA.1 (35.7%), 256 BA.2 (57.6%), 1 BA.4 (0.2%) and 10 BA.5 (2.2%) Omicron variants were found. Phylogenetic analysis detected that three new sub-clades, BA.2,3.5, BA.2.56 and BF1, were circulating. CONCLUSIONS: The increase in the incidence of SARS-CoV2 caused the circulation of new emerging variants. Viral evolution calls for continuous genomic surveillance.

FURIN gene variants (rs6224/rs4702) as potential markers of death and cardiovascular traits in severe COVID-19.

Furin is a protease that plays a key role in the infection cycle of SARS-CoV-2 by cleaving the viral proteins during the virus particle assembly. In addition, Furin regulates several physiological processes related to cardio-metabolic traits. DNA variants in the FURIN gene are candidates to regulate the risk of developing these traits as well as the susceptibility to severe COVID-19. We genotyped two functional FURIN variants (rs6224/rs4702) in 428 COVID-19 patients in the intensive care unit. The association with death (N = 106) and hypertension, diabetes, and hyperlipidaemia was statistically evaluated. The risk of death was associated with age, hypertension, and hypercholesterolemia. The two FURIN alleles linked to higher expression (rs6224 T and rs4702 A) were significantly increased in the death cases (odds ratio= 1.40 and 1.43). Homozygosis for the two high expression genotypes (rs6224 TT and rs4702 AA) and for the T-A haplotype was associated with an increased risk of hypercholesterolemia. In the multiple logistic regression both, hypercholesterolemia and the TT + AA genotype were significantly associated with death. In conclusion, besides its association with hypercholesterolemia, FURIN variants might be independent risk factors for the risk of death among COVID-19 patients.

Enhanced Detection of Viral RNA Species Using FokI-Assisted Digestion of DNA Duplexes and DNA/RNA Hybrids.

The accurate detection of nucleic acids from certain biological pathogens is critical for the diagnosis of human diseases. However, amplified detection of RNA molecules from a complex sample by direct detection of RNA/DNA hybrids remains a challenge. Here, we show that type IIS endonuclease FokI is able to digest DNA duplexes and DNA/RNA hybrids when assisted by a dumbbell-like fluorescent sensing oligonucleotide. As proof of concept, we designed a battery of sensing oligonucleotides against specific regions of the SARS-CoV-2 genome and interrogated the role of FokI relaxation as a potential nicking enzyme for fluorescence signal amplification. FokI-assisted digestion of SARS-CoV-2 probes increases the detection signal of ssDNA and RNA molecules and decreases the limit of detection more than 3.5-fold as compared to conventional molecular beacon approaches. This cleavage reaction is highly specific to its target molecules, and no detection of other highly related B-coronaviruses was observed in the presence of complex RNA mixtures. In addition, the FokI-assisted reaction has a high multiplexing potential, as the combined detection of different viral RNAs, including different SARS-CoV-2 variants, was achieved in the presence of multiple combinations of fluorophores and sensing oligonucleotides. When combined with isothermal rolling circle amplification technologies, FokI-assisted digestion reduced the detection time of SARS-CoV-2 in COVID-19-positive human samples with adequate sensitivity and specificity compared to conventional reverse transcription polymerase chain reaction approaches, highlighting the potential of FokI-assisted signal amplification as a valuable sensing mechanism for the detection of human pathogens.

Association between the interferon-induced transmembrane protein 3 gene (IFITM3) rs34481144 / rs12252 haplotypes and COVID-19.

The interferon induced transmembrane-protein 3 (IFITM3) plays an important role in the defence against viral infection. IFITM3 gene variants have been linked to differences in expression and associated with the risk of severe influenza by some authors. More recently, these variants have been associated with the risk of COVID-19 after SARS-CoV-2 infection. We determined the effect of two common IFITM3 polymorphisms (rs34481144 â€‹C/T and rs12252 A/G) on the risk of hospitalization due to COVID-19 by comparing 484 patients (152 required support in thr intensive care unit, ICU) and 182 age and sex matched controls (no disease symptoms). We found significantly higher frequencies of rs34481144 â€‹T and rs12252 â€‹G carriers among the patients (OR â€‹= â€‹2.02 and OR â€‹= â€‹1.51, respectively). None of the two variants were associated with ICU-admission or death. We found a significantly higher frequency of rs34481144 CC â€‹+ â€‹rs12252 AA genotype carriers among the controls, suggesting a protective effect (p = 0.001, OR = 0.56, 95%CI = 0.40-0.80). Moreover, haplotype rs34481144 â€‹C - rs12252 A was significantly increased in the controls (p â€‹= â€‹0.008, OR â€‹= â€‹0.71, 95%CI â€‹= â€‹0.55-0.91). Our results showed a significant effect of the IFITM3 variants in the risk for hospitalization after SARS-CoV-2 infection.

The Interferon-induced transmembrane protein 3 gene (IFITM3) rs12252 C variant is associated with COVID-19.

BACKGROUND AND AIMS: The interferon-induced transmembrane proteins play an important antiviral role by preventing viruses from traversing the cellular lipid bilayer. IFITM3 gene variants have been associated with the clinical response to influenza and other viruses. Our aim was to determine whether the IFITM3 rs12252 polymorphism was associated with the risk of developing severe symptoms of COVID-19 in our population. METHODS: A total of 288 COVID-19 patients who required hospitalization (81 in the intensive care unit) and 440 age matched controls were genotyped with a Taqman assay. Linear regression models were used to compare allele and genotype frequencies between the groups, correcting for age and sex. RESULTS: Carriers of the minor allele frequency (rs12252 C) were significantly more frequent in the patients compared to controls after correcting by age and sex (p = 0.01, OR = 2.02, 95%CI = 1.19-3.42). This genotype was non-significantly more common among patients who required ICU. CONCLUSIONS: The IFITM3 rs12252 C allele was a risk factor for COVID-19 hospitalization in our Caucasian population. The extent of the association was lower than the reported among Chinese, a population with a much higher frequency of the risk allele.

Angiotensin-converting enzymes (ACE, ACE2) gene variants and COVID-19 outcome.

The Angiotensin system is implicated in the pathogenesis of COVID-19. First, ACE2 is the cellular receptor for SARS-CoV-2, and expression of the ACE2 gene could regulate the individuals susceptibility to infection. In addition, the balance between ACE1 and ACE2 activity has been implicated in the pathogenesis of respiratory diseases and could play a role in the severity of COVID-19. Functional ACE1/ACE2 gene polymorphisms have been associated with the risk of cardiovascular and pulmonary diseases, and could thus also contribute to the outcome of COVID-19. We studied 204 COVID-19 patients (137 non-severe and 67 severe-ICU cases) and 536 age-matched controls. The ACE1 insertion/deletion and ACE2 rs2285666 polymorphism were determined. Variables frequencies were compared between the groups by logistic regression. We also sequenced the ACE2 coding nucleotides in a group of patients. Severe COVID-19 was associated with hypertension male gender (p < 0.001), hypertension (p = 0.006), hypercholesterolaemia (p = 0.046), and the ACE1-DD genotype (p = 0.049). In the multiple logistic regression hypertension (p = 0.02, OR = 2.26, 95%CI = 1.12-4.63) and male gender (p = 0.002; OR = 3.15, 95%CI = 1.56-6.66) remained as independent significant predictors of severity. The ACE2 polymorphism was not associated with the disease outcome. The ACE2 sequencing showed no coding sequence variants that could explain an increased risk of developing COVID-19. In conclusion, an adverse outcome of COVID-19 was associated with male gender, hypertension, hypercholesterolemia and the ACE1 genotype. Our work suggested that the ACE1-I/D might influence COVID-19 severity, but the effect was dependent on the hypertensive status. This result requires further validation in other large cohorts.

Capillary electrophoresis of PCR fragments with 5´-labelled primers for testing the SARS-Cov-2.

Due to the huge demand for SARS-Cov-2 determination,alternatives to the standard qtPCRtestsare potentially useful for increasing the number of samples screened. Our aim was to develop a direct fluorescent PCR capillary-electrophoresis detection of the viral genome. We validated this approach on several SARS-Cov-2 positive and negative samples.We isolated the naso-pharingealRNA from 20 positive and 10 negative samples. The cDNA was synthesised and two fragments of the SARS-Cov-2 were amplified. One of the primers for each pair was 5´-end fluorochrome labelled. The amplifications were subjected to capillary electrophoresis in ABI3130 sequencers to visualize the fluorescent peaks.The two SARS-Cov-2 fragments were successfully amplified in the positive samples, while the negative samples did not render fluorescent peaks. In conclusion, we describe and alternative method to identify the SARS-Cov-2 genome that could be scaled to the analysis of approximately 100 samples in less than 5 h. By combining a standard PCR with capillary electrophoresis our approach would overcome the limits imposed to many labs by the qtPCR and increase the testing capacity.