Pathogenic species of Shigella cause a syndrome called shigellosis. Shigella flexneri (S. flexneri), Shigella boydii (S. boydii), Shigella sonneii (S. sonneii), and Shigella dysenteriae (S. dysenteriae) are four pathogenic Shigella that can cause shigellosis (Niyogi, 2005). Pathogenic species of Shigella invade the epithelium lining the terminal ileum, colon, and rectum (Schnupf and Sansonetti, 2019; Chauhan et al., 2024). The manifestations of the syndrome are so diverse and range from acute watery diarrhea to severe bloody dysentery (Diarrheagenic and Shigella., 2024; Manzanares Villanueva et al., 2024).

Shigellosis occur all over the world in people of all ages, however, it is usually observed in low-income and middle-income settings among children aged 1–4 years (Kapulu et al., 2024). Despite significant decrease in morbidity and mortality during the past decades, Shigella infections continue to be high. Shigella infections are the major cause of bloody diarrhea, which causes ∼700,000 deaths worldwide, annually (Organization WH, 2022).

Although most cases of shigellosis recover within a week, however, severe cases should be treated with antibiotics. Indeed, to prevent complication results, children and immunocompromised people should receive antibiotics. However, because of the emergence of multi-drug resistant (MDR) and extremely-drug resistant (XDR) strains of Shigella, treatment options become limited significantly (Avakh Majalan et al., 2018; Thorley et al., 2023; Tansarli et al., 2023; Shooraj et al., 2024).

To combat the situation, vaccination is a preferred option. It is well stablished that natural Shigella infection confers protection against the homologous serotypes and this is the logic of developing vaccine against the bacteria (Ferreccio et al., 1991; Ashkenazi and Cohen, 2013). The importance of vaccination is unquestionable and many vaccine candidates against pathogenic bacteria are in different preclinical or clinical studies (Hoseini et al., 2021; Hosseini et al., 2020; Kordbacheh et al., 2019; Kordbacheh et al., 2018). The assertion of Susan and Stanley Plotkin clearly shows this importance: “With the exception of safe water, no other modality, not even antibiotics, has had such a major effect on mortality reduction and population growth” (Plotkin and Plotkin, 2012). There have been many attempts to develop an efficient vaccine against Shigella. Different vaccine platforms have been developed for this aim: live-attenuated vaccines (attenuated by serial in vitro passages (Cohen et al., 2022; Meitert et al., 1984) or through recombinant DNA technology (Medeiros et al., 2020)), recombinant protein vaccines (Martinez-Becerra et al., 2012; Bhaumik et al., 2023), killed or inactivated vaccines (Barnoy et al., 2010; Chakrabarti et al., 1999; Mukhopadhaya et al., 2003), etc.

In this study, we evaluated the immunogenicity of a novel multi-epitope vaccine (MEV) candidate against Shigella spp., computationally designed to incorporate conserved immunodominant epitopes from three key antigen classes: outer membrane proteins (OmpC/F), invasive plasmid antigens (IpaA/B/C/D), and the virulence factor VirG (IcsA). MEVs represent an advanced class of recombinant protein vaccines that combine selected epitopes from multiple pathogen antigens to maximize immune coverage while minimizing reactogenicity (Suhrbier, 1997). Using BALB/c mice, we tested the hypothesis that this in silico-designed MEV would elicit robust humoral immunity and cross-serotype protection against lethal Shigella challenge.