Ty21a-PA-01

**Ty21a-PA-01** is an engineered live attenuated oral vaccine derived from the **Salmonella enterica serovar Typhi Ty21a** strain, modified to stably express the protective antigen (PA) of **Bacillus anthracis**. It leverages the established safety profile of Ty21a, which is deficient in galE activity and lacks Vi antigen, enabling limited replication in the gut to induce mucosal immunity while preventing systemic virulence. This recombinant vaccine candidate is designed to confer protection against **inhalation anthrax** through PA-mediated immune responses, building on the Ty21a platform's proven immunogenicity against typhoid fever.[9]