Engineered bispecific antibodies with enhanced breadth and potency against SARS-CoV-2 variants and SARS-related coronaviruses.

The concern of COVID-19 persists due to the continuous emergence of variants and the potential spillover of animal coronaviruses. The broad-spectrum neutralizing antibodies play a pivotal role in the prevention and treatment of coronavirus (CoV) infections. Here, we constructed 18 bi-specific antibodies (bsAbs) using 9 antibodies isolated from COVID-19 convalescents and vaccinated individuals, designed as dual variable domain immunoglobulin (DVD-Ig). A bsAb 5-HI showed a high binding capability to the S1 subunit of spike and exhibited breadth and potency against pseudotyped SARS-CoV-2 variants of concerns (VOCs) and SARS-related-CoVs (SARSr-CoVs), with half maximal effective concentration (EC) of 0.028-3.444 nM and 50% inhibitory concentration (IC) of 0.008-0.800 nM. In addition, it retained neutralization potency against the peudotyped virus of recently prevalent JN.1 strain (IC, 12.74 nM). We found that the parental antibodies showed weak or no binding to the receptor binding domain (RBD) of the SARS-CoV, EG.5.1, and JN.1. However, the 5-HI maintained the binding with RBD and prevented the binding between hACE2 and RBD (IC for the RBD of SARS-CoV, 1.067 nM; EG.5.1, 0.423 nM; JN.1, 0.223 nM). In neutralization assays with the authentic virus, we found that the 5-HI effectively neutralized Omicron variants XBB.1.5 (IC, 0.308 nM), EG.5.1 (IC, 0.129 nM), and JN.1 (IC, 13.692 nM), while its parental antibodies showed weakened or no neutralization. Therefore, the 5-HI represents a promising candidate for further development in the treatment and prevention of ongoing evolved SARS-CoV-2 VOCs and other SARSr-CoVs that potentially emerge in the future.