MERS-CoV‒Specific T-Cell Responses in Camels after Single MVA-MERS-S Vaccination.

We developed an ELISPOT assay for evaluating Middle East respiratory syndrome coronavirus (MERS-CoV)‒specific T-cell responses in dromedary camels. After single modified vaccinia virus Ankara-MERS-S vaccination, seropositive camels showed increased levels of MERS-CoV‒specific T cells and antibodies, indicating suitability of camel vaccinations in disease-endemic areas as a promising approach to control infection.

Safety and immunogenicity of the ChAdOx1, MVA-MERS-S, and GLS-5300 DNA MERS-CoV vaccines.

BACKGROUND: The Middle East respiratory syndrome coronavirus (MERS-CoV) is a pathogen associated with an acute respiratory infection that has a high mortality rate in humans. It was first identified in June of 2012 in the Arabian Peninsula. The success of the COVID-19 vaccines has shown that it is possible to take advantage of medical and scientific advances to produce safe and effective vaccines for coronaviruses. This study aimed to examine the safety and immunogenicity of MERS-CoV vaccines. METHODS: The research method Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA) was used as the guideline for this study. RevMan 5.4 software was used to perform a meta-analysis of the included studies. The safety was assessed by recording adverse events following vaccination, and the immunogenicity was assessed by using seroconversion. RESULTS: The study included five randomized controlled trials that met the inclusion criteria after screening. The studies had 173 participants and were performed in four countries. The vaccines examined were the ChAdOx1 MERS vaccine, MVA-MERS-S vaccine, and GLS-5300 DNA MERS-CoV vaccine. The meta-analysis showed no significant differences in local adverse effects (all local adverse effects and pain) or systemic adverse effects (all systemic adverse effects, fatigue, and headache) among participants in groups receiving a high-dose vaccine or a low-dose vaccine. There were, however, higher levels of seroconversion in high-dose groups than in low-dose groups (OR 0.16 [CI 0.06, 0.42, p = 0.0002]). CONCLUSION: The findings showed that high doses of current MERS-CoV vaccine candidates conferred better immunogenicity than low doses and that there were no differences in the safety of the vaccines.

Persistence of MERS-CoV-spike-specific B cells and antibodies after late third immunization with the MVA-MERS-S vaccine.

The Middle East respiratory syndrome (MERS) is a respiratory disease caused by MERS coronavirus (MERS-CoV). In follow up to a phase 1 trial, we perform a longitudinal analysis of immune responses following immunization with the modified vaccinia virus Ankara (MVA)-based vaccine MVA-MERS-S encoding the MERS-CoV-spike protein. Three homologous immunizations were administered on days 0 and 28 with a late booster vaccination at 12 ± 4 months. Antibody isotypes, subclasses, and neutralization capacity as well as T and B cell responses were monitored over a period of 3 years using standard and bead-based enzyme-linked immunosorbent assay (ELISA), 50% plaque-reduction neutralization test (PRNT50), enzyme-linked immunospot (ELISpot), and flow cytometry. The late booster immunization significantly increases the frequency and persistence of spike-specific B cells, binding immunoglobulin G1 (IgG1) and neutralizing antibodies but not T cell responses. Our data highlight the potential of a late boost to enhance long-term antibody and B cell immunity against MERS-CoV. Our findings on the MVA-MERS-S vaccine may be of relevance for coronavirus 2019 (COVID-19) vaccination strategies.