Intranasal DNA Vaccine for Protection against Respiratory Infectious Diseases: The Delivery Perspectives

Xu, Yingying; Yuen, Pak-Wai; Lam, Jenny Ka-Wing

Understanding the pathogenesis of the Bell's palsy that was connected to NasalFlu has become an important research focus for vaccine development. Following intranasal administration in mice, enterotoxins were found in the olfactory nerve and the olfactory bulb for an extended period. Since the olfactory epithelium is the only part of the central nervous system (CNS) that is exposed to the external environment, drugs and nanoparticles, including intranasal vaccines, may bypass the blood brain barrier and enter the CNS through olfactory transmission. There is a reason to concern the neurotoxic effects of vaccine containing enterotoxin adjuvant for intranasal administration. While the nasal delivery of neuronal-binding LT-derived adjuvants is inadvisable [71] , other toxin-derived adjuvants such as cholera toxin-derived CTA-DD and double mutant cholera enterotoxin (CT) are claimed to be safe and effective adjuvant candidates without causing any inflammation or CNS toxicity [72, 73] . Nevertheless, thorough evaluation must be performed with the use of toxin derivatives as intranasal vaccine adjuvants. Tremendous efforts are now focusing on the development of alternative adjuvants with better safety profile.