A potential delivery system based on cholera toxin: A macromolecule carrier with multiple activities.

Macromolecular drugs are widely thought to be one of the most promising fields, but there are still many problems, especially with regard to drug delivery. Drug delivery systems are focused on loading efficiency without loss of activity, effective cellular internalization, anti-degradation, target ability, etc. New directions for macromolecular drugs delivery systems are not only to retain the activity of drugs, but bring new bioactivity to carry out dual benefits. Cholera toxin (CT) from Vibrio cholerae is one of such delivery systems and plays a potential role in delivering macromolecular drugs. After released from V. cholerae in the intestine, the B subunit of CT binds to the ganglioside GM1 on intestinal cells, and then the toxin gains access into the intestine. CT has potential as a "vaccine adjuvant-delivery system" (VADS) and is able to bring antigens and serve as adjuvants to induce specific immunity. In addition, it has been well used in the field of mucosal drug delivery and neural targeting. However, native CT is toxic, which restricts its practical application. There are several CT-based proteins with reduced virulence and reserved or even enhanced adjuvant activity under research. In this review, we comprehensively summarize the preparation strategy, advantages, applications and corresponding deficiencies of CT-based proteins. CT is focused on a delivery system when delivering macromolecular cargos such as active protein/peptide and antigen/antigen peptide. CT-based drug delivery system deserves further study due to their superiority.