Current progress in the development of prophylactic and therapeutic vaccines

Vaccines are essential public health tools and play an important role in reducing the burden of infectious diseases in the population.Emerging infectious diseases and outbreaks pose new challenges for vaccine development,requiring the rapid design and production of safe and effective vaccines against diseases with limited resources.Here,we focus on the development of vaccines in broad fields ranging from conventional prophylactic vaccines against infectious diseases to therapeutic vaccines against chronic diseases and cancer,providing a comprehensive overview of recent advances in eight different vaccine forms(live attenuated vaccines,inactivated vaccines,polysaccharide and polysaccharide conjugate vaccines,recombinant subunit vaccines,virus-like particle and nanoparticle vaccines,polypeptide vaccines,DNA vaccines,and m RNA vaccines)and the therapeutic vaccines against five solid tumors(lung cancer,breast cancer,colorectal cancer,liver cancer and gastric cancer),three infectious diseases(human immunodeficiency virus,hepatitis B virus and human papillomavirus-induced diseases)and three common chronic diseases(hypertension,diabetes mellitus and dyslipidemia).We aim to provide new insights into vaccine technologies,platforms,applications and understanding of potential next-generation preventive and therapeutic vaccine technologies,paving the way for the vaccines design in the future.

Development of mRNA vaccines and their prophylactic and therapeutic applications

Nucleic acid vaccines have attracted enormous attention for resolving the limitations of conventional vaccines using live attenuated viruses. Because nucleic acid vaccines can be produced rapidly in response to the emergence of new virus strains, they are more appropriate for the control of urgent epidemic and pandemic issues. In particular, messenger RNA （mRNA） vaccines have evolved as a new type of nucleic acid vaccines in accordance with their superior protein expression and a lack of mutagenesis as compared with DNA vaccines. Using mRNA vaccines, large amounts of target proteins can be expressed in immune cells for efficient immunization. For instance, antigen-specific vaccination is a feasible option involving the expression of specific antigens in antigen-presenting cells. Immunological reactions are modulated by expressing several proteins associated with stimulation or maturation of immune cells. In addition, mRNA vaccines can stimulate innate immunity through specific recognition by pattern recognition receptors. On the basis of these remarkable properties, mRNA vaccines have been used for prophylactic and therapeutic applications. This review highlights the role of mRNA vaccines as prophylactic vaccines for prevention of future infections and as therapeutic vaccines for cancer immunotherapy. In addition to the conventional type of mRNA vaccines, RNA replicons （self-amplifying mRNA vaccines） will be described.