Monitoring and Tracking the Spread of SARS-CoV-2 in Asturias, Spain

Mutational analysis of SARS-CoV-2 can quantify their relative importance over time, enable the dominant mutations to be identified and facilitate near real-time detection, comparison, and tracking of evolving variants. Collected samples in Asturias an autonomous community of Spain with a large aged population, and high levels of migration and tourism was monitored and tracked from its beginning in February 2020 until its decline and stabilization in August 2021, were characterized using whole genomic sequence and single nucleotide polymorphism. Data held in the GISAID database was analyzed to establish patterns in the appearance and persistence of SARS-CoV-2 strains. Only 138 non-synonymous mutations occurring in more than 1% of the population of SARS-CoV-2 were found, identifying 10 major variants worldwide (7 arose before January 2021), 19 regional and 1 local. In Asturias only 17 different variants were found. After vaccination, no further regional majority variants were found. Only half of the defined variants circulated and no new variants were generated, indicating that infection control measures (fast diagnosis, prevention measures and vaccination) were efficient.

Comparison of Fourteen Rapid Point-of-Care Antigen Tests for SARS-CoV-2: Use and Sensitivity

Fast, sensitive techniques are advisable for SARS-CoV-2 detection. Various rapid SARS-CoV-2 antigen detection tests have been developed, but type and quality of the sample, stage of the disease and viral load can all have an impact on their sensitivity. For this study, a total of 486 swabs were processed and checked with various commercially available tests and then compared with q(RT)-PCR (the gold-standard method). Total sensitivity varied considerably;for example, 42.10% (nal von minden and Tody Laboratories), 68.42% (Cahnos) and 84.78% (PCL). Sensitivity reached 100% when the cycle threshold (Ct) was lower than 22 in almost all tests, although this dropped considerably when the Ct was higher above 30, where only 3 tests identified 40% or more positive samples and in 5 cases it was 0%. What is more, only 2 cases were 100% accurate when viral load was higher than 5 log/103 cells and accuracy was 0% in 12 cases when viral load was lower than 4 log/103 cells. These results, particularly taking into consideration the fact that they used normalized viral load, suggest that antigen detection tests have their role in the fast triage of positive patients, but that considerable care should be taken with negative results, which is even more important if they are used for massive screening.

Utilization of Microwaves: A Novel Approach to SARS-CoV-2 Genome Extraction

In this study, an innovative approach to the heat extraction method has been tested: the use of microwaves, which can dramatically decrease the time that is needed to do the genome extraction. The method can obtain the virus with enough quality to assure the identification by RT-qPCR and minimize procedures and contaminations.

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.

Comparison of in-house SARS-CoV-2 genome extraction procedures. A need for COVID-19 pandemic.

Among the methods used to diagnose COVID-19, those based on genomic detection by q(RT)-PCR are the most sensitive. To perform these assays, a previous genome extraction of the sample is required. The dramatic increase in the number of SARS-CoV-2 detection assays has increased the demand for extraction reagents hindering the supply of commercial reagents. Homemade reagents and procedures could be an alternative. Nasopharyngeal samples were extracted by seven different methods as well as the automatic method MagNaPure96, to detect SARS-CoV-2. All protocols show sensitivity higher than 87 %, in comparison with reference method, for detecting SARS-CoV-2 as well as human ß- globin. Our results support that these procedures, using common and cheap reagents, are effective to extract RNA (from SARS-CoV-2) or DNA (from human ß-globin) genome from nasopharyngeal swabs. Furthermore, these procedures could be easily adopted by routine diagnostic laboratories to implement detection methods to help to fight against COVID-19 pandemic.

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.

Viviendo una pandemia

El SARS-CoV-2 apareció por primera vez en diciembre de 2019 en Wuhan (China) y desde ese momento se expandió por el resto del mundo causando una pandemia como no se había visto recientemente. El rápido diagnóstico del virus y las medidas de prevención de la infección se ha visto que son las herramientas fundamentales para contener el virus. En este artículo se relata cómo se vivió esta pandemia desde un laboratorio de virología.

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.