Identification of cross-reacting IgG hotspots to prevent immune evasion of SARS-CoV-2 variants

The major factor that shapes the global perspective for increase or diminution of successive pandemic waves of COVID-19 is the immunological protection. The SARS-CoV-2 virus constantly develops new variants, and capability of immune evasion is among the major factors that promote variant spreading in the human population. After two years of the pandemic and virus evolution, it is almost impossible to explain effects of all possible combinations different viral strains, a few types of vaccinations or new variants infecting an individual patient. Instead of variant-to-variant comparisons, identification of key protein regions linked to immune evasion could be efficient. Here we report an approach for experimental identification of SARS-CoV-2 protein regions that (i) have characteristics of cross-reacting IgG hot-spots, and (ii) are highly immunogenic. Cross-reacting IgG hot spots are regions of protein frequently recognized in many variants by cross-reacting antibodies. Immunogenic regions efficiently induce specific IgG production in SARS-CoV-2 infected patients. We determined four regions that demonstrate both significant immunogenicity and the activity of a cross-reacting IgG hot-spot in protein S, and two such regions in protein N. Their distribution within the proteins suggests that they may be useful in vaccine design and in serological diagnostics of COVID-19.