Mutation D614G stabilizes spike protein and increases infectiousness of SARS-COV-2; mutated virus dominates new infections

sars-cov-2 virions (complete virus) in EM by NIAID (via Medscape.com)

A Scripps Research post dated June 12 describes a mutation called D614G in the novel coronavirus that has come to dominate new infections.  The mutation, changes a glycine residue to an aspartic acid residue in the spike protein and stabilizes the spike by making it more flexible.  This leads to a 4-5X increase in the number of functional spikes on each virus particle (virion) which improves the virus’ ability to bind to and infect human cells.  The research behind this finding is described in the paper “The D614G mutation in the SARS-CoV-2 spike protein reduces S1 shedding and increases infectivity” published by Scripps as a pre-print (before peer review.)

The research was done with a harmless coronavirus ( Maloney murine leukemia virus (MLV)-based pseudoviruses (PVs)) engineered to express the same spike protein as the pathogenic virus.  The mutation does not appear to reduce the effectiveness of neutralizing antibodies raised against the SARS-COV-2 virus during natural infection, so there is probably no difficulty with vaccines that are currently being developed.

The mutation does not appear to increase severity of infection.  The mutated virus has come to dominate new infections, probably because it is much more efficient at spreading.  According to the Scripps Research post, “It is still unknown whether this small mutation affects the severity of symptoms of infected people, or increases mortality, the scientists say. While ICU data from New York and elsewhere reports a preponderance of the new D614G variant, much more data, ideally under controlled studies, are needed…”

The novel coronavirus will continue to mutate.  This mutation appears to increase the efficiency of transmission but apparently without making it more severe.  Future changes in the virus genome will have unanticipated effects, but they are unlikely to change the basic strategy for preventing transmission: mask wearing, physical distancing (six feet where possible), and frequent hand-washing or sanitizing before and after being in public.