DR DOUG QUARRY
South African variant probably still susceptible to vaccine-derived immunity. Various recent reports have suggested that that the South African variant of SARS-CoV-2 may be able to escape vaccine-induced immunity.
On 4 January 2021, Bloom Laboratories released a non-peer reviewed paper mapping how convalescent serum antibodies are impacted by mutations to the spike’s receptor-binding domain (RBD), the main target of serum neutralizing activity.
Among the implications presented in the paper were:
- E484K (South African lineage) worrying for immune escape
- RBD mutations in UK lineage less so
Here we present tweeted analyses of the paper by Dr Ali Nouri** and Dr Scott Gottlieb***
Dr. Ali Nouri
- The emerging variants in South Africa and Brazil that harbor the E484K mutation have “greatly reduced susceptibility” to neutralization by polyclonal serum antibodies derived from some individuals. This may have consequences for vaccines.
- The “Receptor Binding Domain” on the spike protein of the virus is a critical site for antibodies to bind to because those antibodies can block the virus from binding the ACE2 receptor on our cells. Mutations at that site are allowing the virus to escape antibodies.
- Report shows neutralizing activity of convalescent sera (rich in polyclonal antibodies) was reduced >10-fold because of single mutation in RBD domain. They also found some sera samples that still neutralized, perhaps through antibodies binding other critical regions of spike.
- This is worrying but the fact that neutralizing function was diminished, not eliminated, suggests a strong vaccine response will protect against the variant.
- However, failure to control the pandemic gives the virus more opportunities to evade vaccines.
Dr Scott Gottlieb
- Elegant work at Bloom lab suggests mutation to receptor binding domain in COVID variant that emerged in South Africa and now Brazil could partially escape medical countermeasures and prior immunity
- Both countries are having dense epidemics in their summer
International SOS comment: We await further research into the South African variant. It appears likely that it is still susceptible to vaccine-derived immunity however the current epidemics in South Africa and Brazil may allow further mutation to occur.
** Dr Ali Nouri: Molecular Biologist; President, Federation of American Scientists; National Academy Science Diplomacy Roundtable.
*** Dr Scott Gotlieb: Commissioner of the US Food and Drug Administration (FDA) 2017-2019, Resident Fellow at American Enterprise Institute
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