Evaluation of Live Attenuated Shigella dysenteriae Type 1 Strain as a Candidate Vaccine

This study aims to detect the ipaD plasmid in Shigella dysenteriae type 1 and evaluate the invasive ability of a live, attenuated Shigella dysenteriae type 1 generated from deletion of the ipaD plasmid. The attenuated strain was tested in guinea pigs. We performed biochemical and antibody tests in addition to PCR analysis, to identify the strain and serotype of an isolated Shigella strain. The plasmid version of the ipaD gene was recognized. We generated a live, attenuated Shigella serotype by deletion of the plasmid version of the ipaD gene, which was confirmed by the above mentioned tests. Absence of the ipaD gene was assessed in a PCR reaction and compared to the wild type strain. Various dilutions of cultured bacteria were prepared and colony numbers counted. We prepared specific dilution which was appropriate for conducting the keratoconjunctive test. We used 6 guinea pigs that were divided into two groups, control (n=3) and experimental (n=3). C Invasion capability of produced strain was evaluated by keratoconjunctive test in guinea pigs.The produced live attenuated Shigella dysenteriae type 1 was confirmed through serological tests and PCR. Absence of ipaD was confirmed. Results of keratoconjunctive test has shown that this strain lost its ability to invade host cells. The plasmid version of ipaD gene plays a critical role in Shigella invasiveness. Deletion of mentioned gene reduces the invasion ability of these bacteria. Therefore, Live attenuated ΔipaD shigella dysenteriae can be an appropriate candidate to produce vaccine against shigellosis.