SARS-CoV-2: Proof of recombination between strains and emergence of possibly more virulent ones

Abstract

AbstractCOVID-19 is challenging healthcare preparedness, world economies, and livelihoods. The infection and death rates associated with this pandemic are strikingly variable in different countries. To elucidate this discrepancy, we analyzed 2431 early spread SARS-CoV-2 sequences from GISAID. We estimated continental-wise admixture proportions, assessed haplotype block estimation, and tested for the presence or absence of strains recombination. Herein, we identified 1010 unique missense mutations and seven different SARS-CoV-2 clusters. In samples from Asia, a small haplotype block was identified; whereas, samples from Europe and North America harbored large and different haplotype blocks with nonsynonymous variants. Variant frequency and linkage disequilibrium varied among continents, especially in North America. Recombination between different strains was only observed in North American and European sequences. Additionally, we structurally modeled the two most common mutations D614G and P314L which suggested that these linked mutations may enhance viral entry and stability. Overall, we propose that COVID-19 virulence may be more severe in Europe and North America due to coinfection with different SARS-CoV-2 strains leading to genomic recombination which might be challenging for current treatment regimens and vaccine development. Furthermore, our study provides a possible explanation for the more severe second wave of COVID-19 that many countries are currently experiencing presented as higher rates of infection and death.