Genomic analysis of early SARS-CoV-2 strains introduced in Mexico

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Abstract

The COVID-19 pandemic has affected most countries in the world. Studying the evolution and transmission patterns in different countries is crucial to implement effective strategies for disease control and prevention. In this work, we present the full genome sequence for 17 SARS-CoV-2 isolates corresponding to the earliest sampled cases in Mexico. Global and local phylogenomics, coupled with mutational analysis, consistently revealed that these viral sequences are distributed within 2 known lineages, the SARS-CoV-2 lineage A/G, containing mostly sequences from North America, and the lineage B/S containing mainly sequences from Europe. Based on the exposure history of the cases and on the phylogenomic analysis, we characterized fourteen independent introduction events. Additionally, three cases with no travel history were identified. We found evidence that two of these cases represent local transmission cases occurring in Mexico during mid-March 2020, denoting the earliest events described in the country. Within this Mexican cluster, we also identified an H49Y amino acid change in the spike protein. This mutation is a homoplasy occurring independently through time and space, and may function as a molecular marker to follow on any further spread of these viral variants throughout the country. Our results depict the general picture of the SARS-CoV-2 variants introduced at the beginning of the outbreak in Mexico, setting the foundation for future surveillance efforts.

This work is the result of the collaboration of five institutions into one research consortium: three public health institutes and two universities. From the beginning of this work, it was agreed that the experimental leader of each institution would share the first authorship. Those were the criteria followed to assign first co-first authorship in this manuscript. The order of the other authors was randomly assigned.

IMPORTANCE

Understanding the introduction, spread and establishment of SARS-CoV-2 within distinct human populations is crucial to implement effective control strategies as well as the evolution of the pandemics. In this work, we describe that the initial virus strains introduced in Mexico came from Europe and the United States and the virus was circulating locally in the country as early as mid-March. We also found evidence for early local transmission of strains having the mutation H49Y in the Spike protein, that could be further used as a molecular marker to follow viral spread within the country and the region.

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  1. SciScore for 10.1101/2020.05.27.120402: (What is this?)

    Please note, not all rigor criteria are appropriate for all manuscripts.

    Table 1: Rigor

    Institutional Review Board Statementnot detected.
    Randomizationnot detected.
    Blindingnot detected.
    Power Analysisnot detected.
    Sex as a biological variablenot detected.

    Table 2: Resources

    No key resources detected.


    Results from OddPub: We did not detect open data. We also did not detect open code. Researchers are encouraged to share open data when possible (see Nature blog).


    Results from LimitationRecognizer: An explicit section about the limitations of the techniques employed in this study was not found. We encourage authors to address study limitations.

    Results from TrialIdentifier: No clinical trial numbers were referenced.


    Results from Barzooka: We did not find any issues relating to the usage of bar graphs.


    Results from JetFighter: We did not find any issues relating to colormaps.


    Results from rtransparent:
    • No conflict of interest statement was detected. If there are no conflicts, we encourage authors to explicit state so.
    • Thank you for including a funding statement. Authors are encouraged to include this statement when submitting to a journal.
    • No protocol registration statement was detected.

    About SciScore

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