Development of MVA-d34 Tetravalent Dengue Vaccine: Design and Immunogenicity.

Dengue fever, an infectious disease that affects more than 100 million people every year, is a global health problem. Vaccination may be the most effective prevention strategy for the disease. However, the development of vaccines against dengue fever is complicated by the high risk of developing an antibody-dependent increase in infection. This article describes the development of an MVA-d34 vaccine against the dengue virus based on a safe and effective MVA viral vector. The DIII domains of the envelope protein (E) of the dengue virus are used as vaccine antigens, as antibodies against these domains do not cause an enhancement of infection. The use of the DIII domains of each of the four dengue virus serotypes made it possible to generate a humoral response against all four dengue virus serotypes in immunized mice. We also showed that the sera of vaccinated mice present virus-neutralizing activity against dengue serotype 2. Thus, the developed MVA-d34 vaccine is a promising candidate vaccine against dengue fever.

Structural characterization of ß-propiolactone inactivated severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) particles.

The severe COVID-19 pandemic drives the research toward the SARS-CoV-2 virion structure and the possible therapies against it. Here, we characterized the ß-propiolactone inactivated SARS-CoV-2 virions using transmission electron microscopy (TEM) and atomic force microscopy (AFM). We compared the SARS-CoV-2 samples purified by two consecutive chromatographic procedures (size exclusion chromatography [SEC], followed by ion-exchange chromatography [IEC]) with samples purified by ultracentrifugation. The samples prepared using SEC and IEC retained more spikes on the surface than the ones prepared using ultracentrifugation, as confirmed by TEM and AFM. TEM showed that the spike (S) proteins were in the pre-fusion conformation. Notably, the S proteins could be recognized by specific monoclonal antibodies. Analytical TEM showed that the inactivated virions retained nucleic acid. Altogether, we demonstrated that the inactivated SARS-CoV-2 virions retain the structural features of native viruses and provide a prospective vaccine candidate.