Spike nanoparticle and recombinant adenovirus 5 vaccines induce specific antibodies against the Middle East respiratory syndrome coronavirus (MERS-CoV)

Abstract

Abstract The Middle East respiratory syndrome coronavirus (MERS-CoV) is a single-strained RNA virus and is included in Betacoronavirus. While, in the Arabian Peninsula, it has shown an endemic pattern, a sporadic pattern was observed elsewhere. In 2015, there was big outbreak of the MERS-CoV in Korea. However, since we still have no clinically available vaccine to prevent the MERS-CoV infection, such a vaccine is urgently required. In the present study, we developed two types of MERS-CoV vaccines: a spike nanoparticle vaccine produced by an insect culture system and a recombinant adenovirus 5 vaccine expressing spike protein. Both vaccines induced total IgG, IgG1, and IgG2a against spike protein of the MERS-CoV. Thus, both vaccines can trigger Th1 and Th2 immune responses. Interestingly, as compared to spike nanoparticle formulation with Alum without RNA adjuvant, spike nanoparticle formulation with Alum and RNA adjuvant showed higher titers of IgG1 and IgG2a at 10 days after boosting immunization. Moreover, T cell proliferation in splenocytes of immunized mice was well induced after the spike nanoparticle treatment. Thus, RNA adjuvant may be effective to increase vaccine efficacy against the MERS-CoV. Taken together, the results of the present study suggest that the developed two type of MERS-CoV vaccines–the spike nanoparticle vaccine and the recombinant virus vaccine–may be helpful to prevent the spread of the MERS-CoV.