Shigella dysenteriae 1 strain WRSd1 vaccine obsolete S. dysenteriae 1 strain WRSd1 true An aroA and virG mutant (CVD 1203) is attenuated in guinea pigs, as shown by the Sereny test. Guinea pigs inoculated with CVD 1203 were also protected from challenge with wild type S. flexneri Rebecca Racz Oliver He terms merged