Immunogenicity of High-Dose MVA-Based MERS Vaccine Candidate in Mice and Camels

Abstract

The Middle East respiratory syndrome coronavirus (MERS-CoV) is a zoonotic pathogen that can transmit from dromedary camels to humans, causing severe pneumonia, with a 35% mortality rate. Vaccine candidates have been developed and tested in mice, camels, and humans. Previously, we developed a vaccine based on the modified vaccinia virus Ankara (MVA) viral vector, encoding a full-length spike protein of MERS-CoV, MVA-MERS. Here, we report the immunogenicity of high-dose MVA-MERS in prime–boost vaccinations in mice and camels. Methods: Three groups of mice were immunised with MVA wild-type (MVA-wt) and MVA-MERS (MVA-wt/MVA-MERS), MVA-MERS/MVA-wt, or MVA-MERS/MVA-MERS. Camels were immunised with two doses of PBS, MVA-wt, or MVA-MERS. Antibody (Ab) responses were evaluated using ELISA and MERS pseudovirus neutralisation assays. Results: Two high doses of MVA-MERS induced strong Ab responses in both mice and camels, including neutralising antibodies. Anti-MVA Ab responses did not affect the immune responses to the vaccine antigen (MERS-CoV spike). Conclusions: MVA-MERS vaccine, administered in a homologous prime–boost regimen, induced high levels of neutralising anti-MERS-CoV antibodies in mice and camels. This could be considered for further development and evaluation as a dromedary vaccine to reduce MERS-CoV transmission to humans.

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

“…Animal studies provide an important first step in determining the immunogenicity of a virus. Alharbi et al (2022) and van Doremalen et al (2020) found that the MVA-MERS-S and ChAdOx1 MERS vaccines were effective; they boosted antibody titers and prevented viral replication in animal models [27] , [28] . Other than confirming the boost in antibodies, the human studies included in this paper showed that the impact of the vaccine increased as its dosage increased, as there was a significant difference between the high-dose group and the low-dose group.…”

“…Other than confirming the boost in antibodies, the human studies included in this paper showed that the impact of the vaccine increased as its dosage increased, as there was a significant difference between the high-dose group and the low-dose group. Animal studies will remain an important part of developing a vaccine, given the low number of infections in humans [27] . They also provide more flexibility for examining different doses and frequencies of booster vaccines.…”

Mapping the Middle East Respiratory Syndrome (MERS) related Research – A Scoping Review (2012-2023)

“…Moreover, this review showed that more geographically representative seroprevalence studies should be conducted, particularly in regions with large camel populations. While our review revealed many publications on the evaluation of vaccine candidates for dromedary camels, advancement is still needed as no licensed animal vaccine is available to date [39, 40].…”

Highly Attenuated Poxvirus-Based Vaccines Against Emerging Viral Diseases

“… 176 1 x MVA-MERS-S P/B: MVA-MERS-S Full-length MERS-CoV S glycoprotein (F11L) BALB/c mice Camels P/B: high levels of NAbs in mice and camels. 153 SEVERE ACUTE RESPIRATORY SYNDROME-CORONAVIRUS (SARS-CoV) Homologous or heterologous combinations of NC+MALP-2 (i.n.) and MVA-NC (i.m.)…”

“…151 Thus, no specific vaccine or treatment against MERS-CoV is currently available, although several products are under development. 152 Different studies have reported the preclinical 153 and clinical 154 , 155 evaluation of MVA-based vaccine candidates targeting the MERS-CoV spike (S) glycoprotein. In animal models (mice and camels) MVA-MERS-S induced high levels of NAbs with capacity to reduce the transmission of the virus to humans.…”