PROGRESS TOWARDS DEVELOPMENT OF A VACCINE FOR AMEBIASIS

The application of molecular biologic techniques over the past decade has seen a tremendous growth in our knowledge of the biology of Entamo eba histolytica, the causative agent of amebic dysentery and amebic li ver abscess. This approach has also led to the identification and stru ctural characterization of three amebic antigens, the serine-rich Enta moeba histolytica protein (SREHP), the 170-kDa subunit of the Gal/GalN Ac binding lectin, and the 29-kDa cysteine-rich protein, which all sho w promise as recombinant antigen-based vaccines to prevent amebiasis. In recent studies, an immunogenic dodecapeptide derived from SREHP mol ecule has been genetically fused to the B subunit of cholera toxin, to create a recombinant protein capable of inducing both antiamebic and anti-cholera toxin antibodies when administered by the oral route. Con tinued progress in this area will bring us close to the goal of a cost -effective oral combination ''enteric pathogen'' vaccine, capable of i nducing protective mucosal immune responses to several clinically impo rtant enteric diseases, including amebiasis.