Human parainfluenza virus type 3 (HPIV-3) mainly causes acute respiratory infection among kids under 5 years old and the incidence is merely lower than that of respiratory syncytial virus, among which over half are caused by HPIV-3. This is a serious threat to newborn lives. There is no approved vaccine or drug for HPIV up to now. This review systematically introduce the structure, epidemiology, infection, immunization, and current vaccine development progresses of HPIV-3.

Influenza is an acute respiratory infectious disease caused by influenza virus infection, which leads to serious social burden due to the global epidemics of different degrees in winter and spring every year. Vaccination is an important influenza prevention strategy. Traditional trivalent influenza vaccine consists of two A vaccine strains (H1N1 and H3N2) and one B vaccine strain recommended by WHO based on current epidemic trends. However, the two B strains are prone to mismatch or cross circulation infection, which leads to the declined protection for strain B and increase of influenza morbidity and mortality. In view of the above situation, in February 2012, WHO recommended the use of quadrivalent influenza vaccines containing two strains of B virus vaccine. Subsequently, a variety of quadrivalent influenza vaccines from several companies at home and abroad have been approved and marketed successively. This paper reviews the clinical trials of quadrivalent influenza vaccine.

Currently, vaccine is the most effective measures to control influenza. Traditional vaccines include whole inactivated virus vaccine, split vaccine and live attenuated vaccine. In recent years, new influenza vaccines have gradually become a new research and development trend， including recombinant subunit vaccine, nucleic acid based vaccine, and live virus vector vaccine. As a special form of subunit vaccine, virus-like particle (VLP) vaccine has the advantages of rapid production, good safety, and high immunogenicity. VLPs can efficiently induce humoral and cellular immunity, and can be immunized through multiple routes. A variety of expression systems are used in the preparation of VLPs, among which the most widely used is baculovirus expression system. This article reviews the types, assembly, antigen selection, immune pathways, and research progress of influenza virus VLP vaccines in baculovirus expression system.