Coronaviruses are notorious for their zoonotic potential, illustrated by the sudden emergence of the highly pathogenic SARS- and MERS-coronaviruses. Rapid response against future emerging human-infecting coronaviruses urges the development of broadly-reactive intervention strategies. This can be realized by passive or active immunization targeting highly conserved, vulnerable sites on viral pathogens. Recently identified structures of the coronavirus spike glycoprotein trimers - which are key for virus entry and the major target for neutralizing antibodies - demonstrate the presence of such sites as promising targets of broadly neutralizing antibodies. This proposal aims to elicit, isolate and characterize these broadly-neutralizing antibodies (bNAbs) targeting the members of the betacoronavirus genus, including SARS-CoV and MERS-CoV and other human-infecting coronaviruses. To this end, immunization strategies of ‘humanized’ mice will be applied using heterologous spike proteins of related coronaviruses to focus B-cell responses towards conserved neutralizing epitopes. B-cells will be isolated from immunized mice and monoclonal antibodies will be expressed using hybridoma or single cell sequencing technologies, followed by biochemical and functional screening for bNAbs. Broadly neutralizing antibodies targeting conserved regions of the coronavirus spike protein hold promise as prophylactic and therapeutic intervention strategies against current and future emerging zoonotic coronaviruses. Moreover, discovery of bNAb-epitopes and immunization strategies to elicit these bNAbs may guide development of broadly-reactive vaccines against these emerging coronaviruses.