Ty800

Ty800 is a live attenuated oral vaccine developed to provide rapid, single-dose protection against typhoid fever caused by *Salmonella typhi*. The vaccine was engineered by deleting the *phoP/phoQ* virulence regulatory genes from the *S. typhi* Ty2 strain, which reduces pathogenicity while allowing the immune system to recognize and mount a response against the bacterium. This approach enables immunization without causing disease. Ty800 was originally developed by AVANT Immunotherapeutics and later furthered by Celldex Therapeutics[1][2][4]. It is classified as an investigational biologic therapy and has completed phase 2 clinical trials for prevention of typhoid fever[3].