Résumé
Characterisation of SARS-CoV-2 genetic diversity through space and time can reveal trends in virus importation and domestic circulation, and permit the exploration of questions regarding the early transmission dynamics. Here we present a detailed description of SARS-CoV-2 genomic epidemiology in Ecuador, one of the hardest hit countries during the early stages of the COVID-19 pandemic. We generate and analyse 160 whole genome sequences sampled from all provinces of Ecuador in 2020. Molecular clock and phylgeographic analysis of these sequences in the context of global SARS-CoV-2 diversity enable us to identify and characterise individual transmission lineages within Ecuador, explore their spatiotemporal distributions, and consider their introduction and domestic circulation. Our results reveal a pattern of multiple international importations across the country, with apparent differences between key provinces. Transmission lineages were mostly introduced before the implementation of non-pharmaceutical interventions (NPIs), with differential degrees of persistence and national dissemination.
Sujets)
COVID-19Résumé
SARS-CoV-2, the etiological agent of COVID-19, was first described in Wuhan, China in December 2019 and has now spread globally. Ecuador was the second country in South America to confirm cases and Guayaquil was one of the first cities in the world to experience high mortality due to COVID-19. The aim of this study was to describe the lineages circulating throughout the country and to compare the mutations in local variants, to the reference strain. In this work we used the MinION platform (Oxford Nanopore Technologies) to sequence the whole SARS-CoV-2 genomes of 119 patients from all provinces of Ecuador, using the ARTIC network protocols. Our data from lineage assignment of the one hundred and nineteen whole genomes revealed twenty different lineages. All genomes presented differences in the S gene compared to the Wuhan reference strain, being the D614G amino acid replacement the most common change. The B.1.1.119 lineage was the most frequent and was found in several locations in the Coast and Andean region. Three sequences were assigned to the new B.1.1.7 lineage. Our work is an important contribution to the understanding of the epidemiology of SARS- CoV-2 in Ecuador and South America.
Sujets)
COVID-19Résumé
The permanence of rt-PCR positivity after a long time in COVID-19 patients has prompted the question of whether SARS-CoV-2 could cause a persistent infection or patients can become re-infected by this virus. Both possibilities could have critical implications for the management and control of COVID-19. Here we present the first confirmed case of SARS-CoV-2 reinfection in Ecuador and South America. Materials and methods: Our diagnostic laboratory detected a potential re-infection in one patient who was SARS-COv2 rt-PCR positive twice (in May and July 2020). The first laboratory-confirmed infection presented with mild symptoms and full recovery, reaffirmed by a negative RT-PCR test result obtained two weeks after symptom onset. More severe COVID-19-like symptoms presented again four weeks after the first event, and a third RT-PCR test was performed which resulted positive. The total RNA extraction (from the samples collected on both occasions) was sequenced in an Oxford Nanopore MinION using a tilling PCR protocol developed by the ARTIC-Network, and the reads were analyzed using the artic-medaka consensus generation tool. Anti SARS-CoV-2 IgM and IgG antibodies were investigated. Results: different SARS-CoV-2 variants were identified in each infection event. For the first infection, the genome was assigned to the B1.p9 GISAID clade while the variant associated with the second episode was assigned to the A.1.1 GISAID clade. High levels of both SARS-CoV-2 specific IgM and IgG were observed during the second event.Discussion: a patient with two COVID-19 events presented two different SARS-CoV-2 variants on each event, confirming reinfection. This phenomenon is still considered rare.