ABSTRACT
A number of infectious diseases have been successfully cured in the last few decades by vaccination and thus they are gaining much interest as a tool for preventive medicine. Diptheria, neonatal tetanus, smallpox, and polio myelitis are a few diseases, where vaccination programs have successfully reduced their incidence worldwide. Vaccination or immunization can be defined as intended stimulation of resistance in the body against a specific pathogen. Vaccines can be killed or attenuated depending upon the virulence of the pathogen. A highly virulent one is given as killed vaccine, while the lesser ones are given in attenuated form. These treated microorganisms are unable to cause disease but have the capacity to induce the
immune system to develop a defense mechanism that continuously protects against the disease. Furthermore, the vaccination strategies are improved with the integration of genetics and nanotechnology with it, and as a result, specific antigens or gene sequences can be safely and effectively administered to the body in order to generate immune responses [1]. Conventional vaccines contain either treated microbes (killed or live attenuated) or components of microbes. Even though many of these vaccines play a vital role in controlling the infectious diseases, some do not come up with good protection against disease. Besides, it is not safe and wise to use live vaccines among the growing population of immunocompromised individuals in society. Also there are still a number of diseases for which licensed vaccines are not available yet. To surmount these challenges, vaccines based on naked DNA encoding a protective antigen or isolated polysaccharides and proteins are being developed. Despite the fact that these vaccines are more defined, less reactogenic, and safe, they require adjuvants to improve their efficacy as these vaccines are generally less immunogenic. To enhance the immunogenicity, aluminium-based adjuvants are commonly used but these vaccines may not produce strong cell-mediated immunity and can cause local reactions too [2, 3]. Thus novel adjuvants and delivery systems are needed to be developed for the formulation of effective vaccines. Nanovaccines have emerged out as a novel approach for vaccination in recent years.
