<p>Dysentery caused by <i>Shigella</i> species remains a major health threat to children in low- and middle-income countries. There is no vaccine available. The most advanced candidates, i.e., O-polysaccharide (OPS)-based conjugates, have limited coverage—only against the immunizing serotype. Vaccines based on <i>Shigella</i> conserved proteins are sought for their simplicity and capacity to prevent disease caused by multiple serotypes. We previously reported the broad protective capacity of VirGα, a conserved surface-exposed domain of <i>Shigella</i> virulence factor. Seeking to refine the vaccine antigenic target and achieve scalable manufacturing compatible with Good Manufacturing Practices, we mapped linear B-cell epitopes spanning the entire VirG protein sequence by probing the immune reactivity of 10-mer peptides (overlapping 4–8 aa) with sera from <i>Shigella</i>-infected rhesus monkeys. The surface-exposed VirG₅₃_–₃₅₃ subregion of the passenger α-domain demonstrated the highest and strongest immunoreactivity. VirG₅₃_–₃₅₃ was produced efficiently at a large scale (&gt;150 mg/L) using cell-free protein synthesis. When administered to mice intramuscularly, VirG₅₃_–₃₅₃ elicited robust antibody responses and conferred high levels of protection against the three most prevalent <i>Shigella</i> serotypes (<i>S. flexneri</i> 2a, 3a, and <i>S. sonnei</i>). VirG₅₃_–₃₅₃ evoked the production of Th2-type cytokines by spleen cells from vaccinated mice. A new universal <i>Shigella</i> vaccine based on VirG₅₃_–₃₅₃ meets the World Health Organization’s preferred product specifications. The target antigen refinement and production improvement described here will facilitate the first-in-human studies.</p>