Invasion plasmid antigen proteins (Ipa)

Invasion plasmid antigen (Ipa) proteins are critical virulence factors produced by Shigella sonnei, encoded on a large 220-kb virulence plasmid (Schroeder & Hilbi, 2008). These proteins, including IpaA, IpaB, IpaC, and IpaD, are essential components of the Type III secretion system (T3SS), which functions as a molecular syringe to deliver effectors into host cells (Picking et al., 2005). IpaB and IpaC specifically form the translocon pore in the host cell membrane, enabling bacterial invasion and escape from the phagosome (Blocker et al., 1999). IpaD acts as a scaffold and regulator for the needle tip, controlling the secretion of other effectors (Picking et al., 2005). Due to their high conservation across Shigella species and their indispensable role in pathogenesis, they are major targets for vaccine development, such as the Invaplex complex (Turbyfill et al., 2000). Therapeutic approaches aim to generate neutralizing antibodies that block the T3SS assembly or function, thereby preventing the onset of bacillary dysentery. Research into small molecule inhibitors of the T3SS also targets the interaction between these proteins to disrupt the infection cycle (Barta et al., 2012). These antigens are highly immunogenic, making them ideal candidates for diagnostic and protective applications.

Other names

Ipa proteinsInvasion plasmid antigensIpaAIpaBIpaCIpaDVirulence plasmid antigensInvaplex componentsShigella sonnei invasion plasmid antigens

Inhibition of Type III secretion system (T3SS) mediated host cell invasion via antibody-mediated neutralization or structural disruption of the translocon pore (Turbyfill et al., 2000; Schroeder & Hilbi, 2008).