Multi-antigen intranasal vaccine protects against challenge with sarbecoviruses and prevents transmission in hamsters

Immunization programs against SARS-CoV-2 with commercial intramuscular vaccines prevent disease but are less efficient in preventing infections. Mucosal vaccines can provide improved protection against transmission, ideally for different variants of concern (VOCs) and related sarbecoviruses. Here, we report a multi-antigen, intranasal vaccine, NanoSTING-SN (NanoSTING-Spike-Nucleocapsid), eliminates virus replication in both the lungs and the nostrils upon challenge with the pathogenic SARS-CoV-2 Delta VOC. We further demonstrate that NanoSTING-SN prevents transmission of the SARS-CoV-2 Omicron VOC (BA.5) to vaccine-naïve hamsters. To evaluate protection against other sarbecoviruses, we immunized mice with NanoSTING-SN. We showed that immunization affords protection against SARS-CoV, leading to protection from weight loss and 100% survival in mice. In non-human primates, animals immunized with NanoSTING-SN show durable serum IgG responses (6 months) and nasal wash IgA responses cross-reactive to SARS-CoV-2 (XBB1.5), SARS-CoV and MERS-CoV antigens. These observations have two implications: (1) mucosal multi-antigen vaccines present a pathway to reducing transmission of respiratory viruses, and (2) eliciting immunity against multiple antigens can be advantageous in engineering pan-sarbecovirus vaccines. Here the authors describe an intranasal vaccine that protects against multiple strains of SARS-CoV-2 and SARS-CoV while preventing transmission to vaccine naïve hamsters. Immunized monkeys elicit IgG and nasal IgA responses cross-reactive to several coronaviruses.