Author: Vincent Jiang
Phylogenetic tracing was pioneered by New Zealand in 1979, and was developed by German Mathematicians in 1999. As for what phylogenetic tracing is, it is a mathematical algorithm designed to map the movements of organisms through their DNA. Beforehand, Phylogenetic Tracing was primarily used to map out prehistoric humans in their migration patterns, but can also be used to map out the COVID-19’s outbreak path. Using 160 complete virus genomes from patients, Foster et al. from the University of Cambridge have graphed out the virus’s infection and mutation path.
On this graph it is necessary to identify several key components. First, every little notch on the lines between nodes symbolize a change in the nucleotide in the virus’ DNA, i.e, a mutation. Second the nodes are colored, with the color in each node proportionate to which areas the strand of the virus has infected. Lastly, there have been three discovered distinct “variants” of the virus, variant “A”, variant “B” and variant “C” as labeled on the graph.
Variant A is the one most closely related to the strand discovered in bats, aka the “Original Human Virus”. While this virus was present in Wuhan, the city’s predominant virus type was variant “B”. Variant “B” was Wuhan’s major virus type, but despite being prevalent across all of East Asia, this variant never migrated out of it, suggesting some sort of immunity outside of East Asia. Finally Variant “C” is the virus type that is currently plaguing Europe. Of course, be sure to take the model with a pinch of salt, as it is only a snapshot of COVID-19’s migration and mutation tree, and the true lineage of the virus would be impossible to neatly graph due to all of the rapid mutations.
The important thing to point out though, is that through these genetic networking techniques, researchers claim that they managed to correctly trace already established routes, with mutations and viral lineages inking known outbreaks. Therefore, many scientists argue that Phylogenetic Tracing should be used with the current virus’ genome sequencing to accurately predict future global hotspots and outbreaks.
Reference:
Peter Forster, Lucy Forster, Colin Renfrew, Michael Forster. Phylogenetic network analysis of SARS-CoV-2 genomes. Proceedings of the National Academy of Sciences, 2020; 202004999 DOI: 10.1073/pnas.2004999117
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