Genome analysis of SARS-CoV-2 haplotypes: separation and parallel evolution of the major haplotypes occurred considerably earlier than their emergence in China

Abstract

More than 3 years have passed since the outbreak of COVID-19 and yet, the origin of the causal virus SARS-CoV-2 remains unknown. We examined the evolutionary trajectory of SARS-CoV-2 by analyzing non-redundant genome sets classified based on six closely linked mutations. The results indicated that SARS-CoV-2 emerged in February 2019 or earlier and evolved into three main haplotypes (GL, DS, and DL) before May 2019, which then continued to evolve in parallel. The dominant haplotype GL had spread worldwide in the summer (May to July) of 2019 and then evolved into virulent strains in December 2019 that triggered the global pandemic, whereas haplotypes DL and DS arrived in China in October 2019 and caused the epidemic in China in December 2019. Therefore, haplotype GL neither originated in China nor from the viral strains that caused the epidemic in China. Accordingly, considering data solely from China would be inadequate to reveal the mysterious origin of SARS-CoV-2, emphasizing the necessity of global cooperation.

Keywords

• SARS-CoV-2
• Haplotype
• Genome classification
• MRCA
• Phylogenetic analysis