Geographical Distribution of Genetic Variants and Lineages of SARS-CoV-2 in Chile

SARS-CoV-2 outbreak: role of viral proteins and genomic diversity in virus infection and COVID-19 progression

The severe acute respiratory syndrome coronavirus-2 (SARS-CoV-2) infection is the cause of coronavirus disease 2019 (COVID-19); a severe respiratory distress that has emerged from the city of Wuhan, Hubei province, China during December 2019. COVID-19 is currently the major global health problem and the disease has now spread to most countries in the world. COVID-19 has profoundly impacted human health and activities worldwide. Genetic mutation is one of the essential characteristics of viruses. They do so to adapt to their host or to move to another one. Viral genetic mutations have a high potentiality to impact human health as these mutations grant viruses unique unpredicted characteristics. The difficulty in predicting viral genetic mutations is a significant obstacle in the field. Evidence indicates that SARS-CoV-2 has a variety of genetic mutations and genomic diversity with obvious clinical consequences and implications. In this review, we comprehensively summarized and discussed the currently available knowledge regarding SARS-CoV-2 outbreaks with a fundamental focus on the role of the viral proteins and their mutations in viral infection and COVID-19 progression. We also summarized the clinical implications of SARS-CoV-2 variants and how they affect the disease severity and hinder vaccine development. Finally, we provided a massive phylogenetic analysis of the spike gene of 214 SARS-CoV-2 isolates from different geographical regions all over the world and their associated clinical implications.

Modelling quarantine effects on SARS-CoV-2 epidemiological dynamics in Chilean communes and their relationship with the Social Priority Index

Background

An epidemiological model (susceptible, un-quarantined infected, quarantined infected, confirmed infected (SUQC)) was previously developed and applied to incorporate quarantine measures and calculate COVID-19 contagion dynamics and pandemic control in some Chinese regions. Here, we generalized this model to incorporate the disease recovery rate and applied our model to records of the total number of confirmed cases of people infected with the SARS-CoV-2 virus in some Chilean communes.

Methods

In each commune, two consecutive stages were considered: a stage without quarantine and an immediately subsequent quarantine stage imposed by the Ministry of Health. To adjust the model, typical epidemiological parameters were determined, such as the confirmation rate and the quarantine rate. The latter allowed us to calculate the reproduction number.

Results

The mathematical model adequately reproduced the data, indicating a higher quarantine rate when quarantine was imposed by the health authority, with a corresponding decrease in the reproduction number of the virus down to values that prevent or decrease its exponential spread. In general, during this second stage, the communes with the lowest social priority indices had the highest quarantine rates, and therefore, the lowest effective viral reproduction numbers. This study provides useful evidence to address the health inequity of pandemics. The mathematical model applied here can be used in other regions or easily modified for other cases of infectious disease control by quarantine.

Mutation and SARS-CoV-2 strain competition under vaccination in a modified SIR model

The crisis caused by the COVID-19 outbreak around the globe raised an increasing concern about the ongoing emergence of variants of the virus that may evade the immune response provided by vaccines. New variants appear due to mutation, and as the cases accumulate, the probability of the emergence of a variant of concern increases. In this article, we propose a modified susceptible, infected, and recovered (SIR) model with waning immunity that captures the competition of two strain classes of an infectious disease under the effect of vaccination with a highly contagious and deadlier strain class emerging from a prior strain due to mutation. When these strains compete for a limited supply of susceptible individuals, changes in the efficiency of vaccines may affect the behaviour of the disease in a non-trivial way, resulting in complex outcomes. We characterise the parameter space including intrinsic parameters of the disease, and using the vaccine efficiencies as control variables. We find different types of transcritical bifurcations between endemic fixed points and a disease-free equilibrium and identify a region of strain competition where the two strain classes coexist during a transient period. We show that a strain can be extinguished either due to strain competition or vaccination, and we obtain the critical values of the efficiency of vaccines to eradicate the disease. Numerical studies using parameters estimated from publicly reported data agree with our theoretical results. Our mathematical model could be a tool to assess quantitatively the vaccination policies of competing and emerging strains using the dynamics in epidemics of infectious diseases.

Omicron (B.1.1.529) - A new heavily mutated variant: Mapped location and probable properties of its mutations with an emphasis on S-glycoprotein

Omicron, another SARS-CoV-2 variant, has been recorded and reported as a VoC. It has already spread across >30 countries and is a highly mutated variant. We tried to understand the role of mutations in the investigated variants by comparison with previous characterized VoC. We have mapped the mutations in Omicron S-glycoprotein's secondary and tertiary structure landscape using bioinformatics tools and statistical software and developed different models. In addition, we analyzed the effect of diverse mutations in antibody binding regions of the S-glycoprotein on the binding affinity of the investigated antibodies. This study has chosen eight significant mutations in Omicron (D614G, E484A, N501Y, Q493K, K417N, S477N, Y505H G496S), and seven of them are located in the RBD region. We also performed a comparative analysis of the ΔΔG score of these mutations to understand the stabilizing or destabilizing properties of the investigated mutations. The analysis outcome shows that D614G, Q493K, and S477N mutations are stable mutations with ΔΔG scores of 0.351 kcal/mol, 0.470 kcal/mol, and 0.628 kcal/mol, respectively, according to DynaMut estimations. While other mutations (E484A, N501Y, K417N, Y505H, G496S) showed destabilizing results. The D614G, E484A, N501Y, K417N, Y505H, and G496S mutations increased the molecular flexibility of S-glycoprotein to interact with the ACE2 receptor, increasing the variant's infectivity. Our study will contribute to research on the SARS-CoV-2 variant, Omicron, by providing information on the mutational pattern and exciting properties of these eight significant mutations, such as antibody escape and infectivity quotient (stabilizing or destabilizing; increased or decreased molecular flexibility of S-glycoprotein to interact with the human ACE2 receptor).

Implementation of a COVID-19 Genomic Surveillance Regional Network for Latin America and Caribbean region

The timely release of SARS-CoV-2 first genomic sequences allowed the identification of the etiologic agent and development of diagnostic protocols. Genomic sequencing was a crucial step in generating data for driving laboratory response and detections of SARS-CoV-2 since the start of the COVID-19 pandemic. Because of all the progression and achievements that timely release of genetic sequence data represents in the public health response, the Pan American Health Organization (PAHO) in collaboration with countries' public health laboratories, started implementation of a network for strengthening the Latin America and Caribbean (LAC) region on timely generation of SARS-CoV-2 genomic data. Here we describe the implementation of the COVID-19 Genomic Surveillance Regional Network in the Americas region during the beginning of the pandemic. The establishment of this network has strengthened laboratory response capacity at the country level, as well as facilitated timely release of SARS-CoV-2 genomic information to be used to complement the multiple response strategies for COVID-19 pandemic mitigation. As genomic epidemiology is useful for guiding public health decisions on outbreak and response, we also analysed the first SARS-CoV-2 genomic sequence data from countries of the Latin America and Caribbean Region.

Assessment of Mutations Associated With Genomic Variants of SARS-CoV-2: RT-qPCR as a Rapid and Affordable Tool to Monitoring Known Circulating Variants in Chile, 2021

Since the first report of SARS-CoV-2 infection in humans, the virus has mutated to develop new viral variants with higher infection rates and more resistance to neutralization by antibodies elicited after natural SARS-CoV-2 infection or by vaccines. Therefore, rapid identification of viral variants circulating in the population is crucial for epidemiological assessment and efforts to contain the resurgence of the pandemic. Between January and November 2021, we performed a large variant RT-qPCR-based screening of mutations in the spike protein of 1851 SARS-CoV-2-positive samples derived from outpatients from the UC-Christus Health Network in Chile. In a portion of samples (n = 636), we validated our RT-qPCR-pipeline by WGS, obtaining a 99.2% concordance. Our results indicate that from January to March 2021 there was a dominance of non-identifiable variants by the RT-qPCR-based screening; however, throughout WGS we were able to identify the Lambda (C.37) variant of interest (VOI). From March to July, we observed the rapid emergence of mutations associated with the Gamma variant (P.1), which was quickly replaced by the appearance of a combination of samples harboring mutations associated with the Delta variant (B.1.617.2), which predominated until the end of the study. Our results highlight the applicability of cost-effective RT-qPCR-based screening of mutations associated with known variants of concern (VOC), VOI and variants under monitoring (VUM) of SARS-CoV-2, being a rapid and reliable tool that complements WGS-based surveillance.

Insights into the mutation T1117I in the spike and the lineage B.1.1.389 of SARS-CoV-2 circulating in Costa Rica

Emerging mutations and genotypes of the SARS-CoV-2 virus, responsible for the COVID-19 pandemic, have been reported globally. In Costa Rica during the year 2020, a predominant genotype carrying the mutation T1117I in the spike (S:T1117I) was previously identified. To investigate the possible effects of this mutation on the function of the spike, i.e. the biology of the virus, different bioinformatic pipelines based on phylogeny, natural selection, and co-evolutionary models, molecular docking, and epitopes prediction were implemented. Results of the phylogeny of sequences carrying the S:T1117I worldwide showed a polyphyletic group, with the emergence of local lineages. In Costa Rica, the mutation is found in the lineage B.1.1.389 and it is suggested to be a product of positive/adaptive selection. Different changes in the function of the spike protein and more stable interaction with a ligand (nelfinavir drug) were found. Only one epitope out 742 in the spike was affected by the mutation, with some different properties, but suggesting scarce changes in the immune response and no influence on the vaccine effectiveness. Jointly, these results suggest a partial benefit of the mutation for the spread of the virus with this genotype during the year 2020 in Costa Rica, although possibly not strong enough with the introduction of new lineages during early 2021 which became predominant later. In addition, the bioinformatic analyses used here can be applied as an in silico strategy to eventually study other mutations of interest for the SARS-CoV-2 virus and other pathogens.

Emergence of SARS-CoV-2 Variants in the World: How Could This Happen?

The COVID-19 pandemic has had a significant global impact, with more than 280,000,000 people infected and 5,400,000 deaths. The use of personal protective equipment and the anti-SARS-CoV-2 vaccination campaigns have reduced infection and death rates worldwide. However, a recent increase in infection rates has been observed associated with the appearance of SARS-CoV-2 variants, including the more recently described lineage B.1.617.2 (Delta variant) and lineage B.1.1.529/BA.1 (Omicron variant). These new variants put the effectiveness of international vaccination at risk, with the appearance of new outbreaks of COVID-19 throughout the world. This emergence of new variants has been due to multiple predisposing factors, including molecular characteristics of the virus, geographic and environmental conditions, and the impact of social determinants of health that favor the genetic diversification of SARS-CoV-2. We present a literature review on the most recent information available on the emergence of new variants of SARS-CoV-2 in the world. We analyzed the biological, geographical, and sociocultural factors that favor the development of these variants. Finally, we evaluate the surveillance strategies for the early detection of new variants and prevent their distribution outside these regions.

Clinical and epidemiological characteristics of SARS-CoV-2 virus in ambulatory children under 2 years old

BACKGROUND

SARS-CoV-2 is an emerging virus that has mainly affected adults; hence, most clinical information has been derived from that population. Most pediatric cases are mild and with nonspecific symptoms requiring outpatient management. Children are a major source of spread for most traditional respiratory viruses. Their role in SARS-CoV-2 transmission was thought to be relevant. Children under the age of two comprise a group that is more susceptible to infection since vaccines have not been approved for them until recently. The knowledge of clinical manifestation of COVID-19 in young children is scarce.

OBJECTIVES

To describe the clinical, epidemiological, and demographic characteristics of children under 2 years old with confirmed COVID-19, who did not require hospitalization.

METHODS

This descriptive study was performed from May, 2020 to June, 2021. Children ages 0-2 years with COVID-19, confirmed by transcriptase-polymerase chain reaction assay that were performed in laboratories of the Red de Salud UC CHRISTUS Health Network, were selected to be contacted. If the parents accepted participating and their children were not hospitalized, a survey was sent to the patients' caregivers.

RESULTS

Of the 242 cases, 159 caregivers answered the survey (65.7%). The median age of the subjects was 14 months, and 53.5% were males. Fifty percent had comorbidities, of which one third corresponded to atopy. Ninety eight percent were secondary cases. Most of them were infected within their households (81%). The most frequent sources were their parents, followed by their grandparents. The most common symptom was fever (78%) followed by irritability (67.3%), rhinorrhea (66%), and fatigue (64.8%). Infants less than 6 months old more often presented with conjunctival congestion and less loss of appetite compared to older children (p < 0.05).

CONCLUSIONS

This study provides valuable insights regarding COVID-19 in ambulatory young children. Most cases of SARS-CoV-2 infection in children under 2 years old do not require hospitalization. There was a slight male predominance, and the majority had been infected within their households. SARS-CoV-2 infection should be suspected in children under 2 years old presenting with fever, irritability, fatigue, and rhinorrhea. Children with positive household contacts and fever should also be tested for COVID-19.

SARS-CoV-2 genomic characterization and clinical manifestation of the COVID-19 outbreak in Uruguay

COVID-19 is a respiratory illness caused by severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) and declared by the World Health Organization a global public health emergency. Among the severe outbreaks across South America, Uruguay has become known for curtailing SARS-CoV-2 exceptionally well. To understand the SARS-CoV-2 introductions, local transmissions, and associations with genomic and clinical parameters in Uruguay, we sequenced the viral genomes of 44 outpatients and inpatients in a private healthcare system in its capital, Montevideo, from March to May 2020. We performed a phylogeographic analysis using sequences from our cohort and other studies that indicate a minimum of 23 independent introductions into Uruguay, resulting in five major transmission clusters. Our data suggest that most introductions resulting in chains of transmission originate from other South American countries, with the earliest seeding of the virus in late February 2020, weeks before the borders were closed to all non-citizens and a partial lockdown implemented. Genetic analyses suggest a dominance of S and G clades (G, GH, GR) that make up >90% of the viral strains in our study. In our cohort, lethal outcome of SARS-CoV-2 infection significantly correlated with arterial hypertension, kidney failure, and ICU admission (FDR < 0.01), but not with any mutation in a structural or non-structural protein, such as the spike D614G mutation. Our study contributes genetic, phylodynamic, and clinical correlation data about the exceptionally well-curbed SARS-CoV-2 outbreak in Uruguay, which furthers the understanding of disease patterns and regional aspects of the pandemic in Latin America.

Introduction of SARS-CoV-2 C.37 (WHO VOI lambda) in the Sao Paulo State, Southeast Brazil

The Lambda variants of interest (VOI) (C37/GR/452Q.V1/21G) was initially reported in Lima, Peru but has gained rapid dissemination through other Latin American countries. Nevertheless, the dissemination and molecular epidemiology of the Lambda VOI in Brazil is unknown apart from a single case report. In this respect, we characterized the circulation of the SARS‐CoV‐2 Lambda VOI (C37/GR/452Q.V1/21G) in Sao Paulo State, Brazil. From March to June 2021, we identified seven Lambda isolates in a set of approximately 8000 newly sequenced genomes of the Network for Pandemic Alert of Emerging SARS‐CoV‐2 variants from Sao Paulo State. Interestingly, in three of the positive patients, the Lambda VOI infection was probably related to a contact transmission. These individuals were fully vaccinated to COVID‐19 and presented mild symptoms. The remaining positive for Lambda VOI individuals showed different levels of COVID‐19 symptoms and one of them needed hospitalization (score 5, WHO). In our study, we present a low level of Lambda VOI circulation in the Sao Paulo State. This reinforces the essential role of molecular surveillance for the effective SARS‐CoV‐2 pandemic response, especially in regard to circulating variants.

Our study shows the low circulation of the Lambda variants of interest (VOI) in the São Paulo State.

Two distinct Lambda VOI introductions may have occurred in the Sao Paulo State.

Epidemiological data revealed Lambda VOI transmission in three cases of fully vaccinated individuals.

Genetic diversity of SARS-CoV-2 in South America: demographic history and structuration signals

In 2020, the emergence of SARS-CoV-2 caused a global public health crisis with significant mortality rates and a large socioeconomic burden. The rapid spread of this new virus has led to the appearance of new variants, making the characterization and monitoring of genetic diversity necessary to understand the population dynamics and evolution of the virus. Here, a population-genetics-based study was performed starting with South American genome sequences available in the GISAID database to investigate the genetic diversity of SARS-CoV-2 on this continent and the evolutionary mechanisms that modulate it.

SARS-CoV-2, CT-Values, and Infectivity-Conclusions to Be Drawn from Side Observations

In their recent article published in Viruses, Michel Drancourt and colleagues [...].

Phylogenomics reveals multiple introductions and early spread of SARS-CoV-2 into Peru

Peru has become one of the countries with the highest mortality rates from the current coronavirus disease 2019 (COVID‐19) pandemic caused by the severe acute respiratory syndrome coronavirus 2 (SARS‐CoV‐2). To investigate early transmission events and the genomic diversity of SARS‐CoV‐2 isolates circulating in Peru in the early COVID‐19 pandemic, we analyzed 3472 viral genomes, of which 149 were from Peru. Phylogenomic analysis revealed multiple and independent introductions of the virus likely from Europe and Asia and a high diversity of genetic lineages circulating in Peru. In addition, we found evidence for community‐driven transmission of SARS‐CoV‐2 as suggested by clusters of related viruses found in patients living in different regions of Peru.

This is the first snapshot of the sources of epidemic transmission and genomic diversity of SARS‐CoV‐2 lineages circulating in Peru during the early COVID‐19 pandemic. Phylogenomic analysis revealed multiple and independent introductions of the virus likely from Europe and Asia, and high diversity of genetic lineages circulating in Peru with predominance of the G614G variant (S gene,n= 136/149). We found evidence that early spread of the virus in Lima City was sustained by community transmission.

SARS-CoV-2 genetic diversity in Venezuela: Predominance of D614G variants and analysis of one outbreak

SARS-CoV-2 is the new coronavirus responsible for COVID-19 disease. The first two cases of COVID-19 were detected in Venezuela on March 13, 2020. The aim of this study was the genetic characterization of Venezuelan SARS-CoV-2 isolates. A total of 7 full SARS-CoV-2 genome sequences were obtained by Sanger sequencing, from patients of different regions of Venezuela, mainly from the beginning of the epidemic. Ten out of 11 isolates (6 complete genomes and 4 partial spike genomic regions) belonged to lineage B, bearing the D614G mutation in the Spike protein. Isolates from the first outbreak that occurred in the Margarita Island harbored an in-frame deletion in its sequence, without amino acids 83–85 of the NSP1 of the ORF1. The search for deletions in 48,635 sequences showed that the NSP1 gene exhibit the highest frequency of deletions along the whole genome. Structural analysis suggests a change in the N-terminal domain with the presence of this deletion. In contrast, isolates circulating later in this island lacked the deletion, suggesting new introductions to the island after this first outbreak. In conclusion, a high diversity of SARS-CoV-2 isolates were found circulating in Venezuela, with predominance of the D614G mutation. The first small outbreak in Margarita Island seemed to be associated with a strain carrying a small deletion in the NSP1 protein, but these isolates do not seem to be responsible for the larger outbreak which started in July.

Global Geographic and Temporal Analysis of SARS-CoV-2 Haplotypes Normalized by COVID-19 Cases During the Pandemic

Since the identification of SARS-CoV-2, a large number of genomes have been sequenced with unprecedented speed around the world. This marks a unique opportunity to analyze virus spreading and evolution in a worldwide context. Currently, there is not a useful haplotype description to help to track important and globally scattered mutations. Also, differences in the number of sequenced genomes between countries and/or months make it difficult to identify the emergence of haplotypes in regions where few genomes are sequenced but a large number of cases are reported. We propose an approach based on the normalization by COVID-19 cases of relative frequencies of mutations using all the available data to identify major haplotypes. Furthermore, we can use a similar normalization approach to tracking the temporal and geographic distribution of haplotypes in the world. Using 171,461 genomes, we identify five major haplotypes or operational taxonomic units (OTUs) based on nine high-frequency mutations. OTU_3 characterized by mutations R203K and G204R is currently the most frequent haplotype circulating in four of the six continents analyzed (South America, North America, Europe, Asia, Africa, and Oceania). On the other hand, during almost all months analyzed, OTU_5 characterized by the mutation T85I in nsp2 is the most frequent in North America. Recently (since September), OTU_2 has been established as the most frequent in Europe. OTU_1, the ancestor haplotype, is near to extinction showed by its low number of isolations since May. Also, we analyzed whether age, gender, or patient status is more related to a specific OTU. We did not find OTU's preference for any age group, gender, or patient status. Finally, we discuss structural and functional hypotheses in the most frequently identified mutations, none of those mutations show a clear effect on the transmissibility or pathogenicity.

A review on favipiravir: the properties, function, and usefulness to treat COVID-19

INTRODUCTION

At this time, there is no specific therapeutic or vaccine for treatment of the severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2). Hence, available drugs for treatment of other viral infections may be useful to treat COVID-19.

AREAS COVERED

The focus of the current review was studying the main characteristics of favipiravir and its usefulness to treat COVID-19. An electronic search was done by using Pubmed and Google scholar.

EXPERT OPINION

Based on the mechanism of action and safety of favipiravir, the drug may be a promising candidate for compassionate use against the SARS-CoV-2 infection. Favipiravir has a wide range of activity against many single-stranded RNA viruses, is well tolerated in humans and has a high barrier to resistance. However, high doses of the agent are necessary to obtain an efficient antiviral activity. Favipiravir is teratogen in pregnant women and associated with the hyperuricemia. Therefore, the administration of the drug should be well controlled. Investigating the antiviral prophylactic potency of favipiravir and search for its pro-drugs and/or analogs showing improved activity and/or safety are critical.