David Ho

Antibody Evasion Properties of SARS-CoV-2 Variants

The COVID-19 pandemic has been devastating to the human population over the past three years.  The scientific community has responded brilliantly in rapidly developing effective treatments and preventive measures, including highly protective vaccines against the etiologic agent, SARS-CoV-2.  However, this virus has continued to evolve, producing variants that not only escape from our antibody responses but also capable of more efficient transmission.  Earlier variants like Beta and Delta already led to greater antibody resistance, resulting in lower degree of protection against symptomatic infection by SARS-CoV-2.  But this challenge became greatly exacerbated by the advent of the Omicron variant that was dramatically more resistant to antibody neutralization.  Its subsequent subvariants (BA2, BA4/5) again developed even greater antibody resistance while gaining a transmissible advantage.  The most recent dominant Omicron subvariants (BQ.1.1 and XBB.1.5) are the most extreme in evading existing antibodies.  Essentially, they are refractory to neutralization by all authorized/approved monoclonal antibodies; they are also about 100-fold more resistant to neutralization by vaccinee sera when compared with the ancestral strain of SARS-CoV-2.  Yet by detailed examinations of how the virus is evolving to antibodies, there are indeed strategies we could employ to attack conserved sites on the viral spike and to improve our chance of countering future variants.