The safety and immunogenicity of a protein-based tetravalent vaccine SCTV01E that contains spike protein ectodomain (S-ECD) of Alpha, Beta, Delta and Omicron BA.1 are assessed and compared with bivalent protein vaccine SCTV01C (Alpha and Beta variants) and monovalent mRNA vaccine (NCT05323461). The primary endpoints are the geometric mean titers (GMT) of live virus neutralizing antibodies (nAb) to Delta (B.1.617.2) and Omicron BA.1 at day 28 post-injection. The secondary endpoints include the safety, day 180 GMTs against Delta and Omicron BA.1, day 28 GMTs to BA.5, and seroresponse rates of neutralizing antibodies and T cell responses at day 28 post-injection. 450 participants, comprising of 449 males and 1 female, with a median age (range) of 27 (18–62) years, are assigned to receive one booster dose of BNT162b2, 20 µg SCTV01C or 30 µg SCTV01E and completed 4-week follow-up. All SCTV01E related adverse events (AEs) are mild or moderate and no Grade ≥3 AE, serious AE or new safety concerns are identified. Day 28 GMT of live virus neutralizing antibodies and seroresponse against Omicron BA.1 and BA.5 with SCTV01E are significantly higher than those with SCTV01C and BNT162b2. These data indicate an overall neutralization superiority with tetravalent booster immunization in men.

Foot and mouth disease (FMD) has been endemic in Sudan for decades and causes continuous outbreaks that have a direct negative impact on the animal population and prevent the exportation of animals from the country. The high diversity of FMD serotypes, especially SAT2 and A serotypes, hinders the development of effective vaccines since the most important component of vaccination is the degree of cross-protection provided by the vaccine against currently circulating field viruses. An immunoinformatic approach was utilized to predict a multi-epitope peptide vaccine design against the SAT2 serotype from a Sudanese isolate targeting virus capsid region P1. The virus capsid region P1 comprises the major immunogenic epitopes that confer protection against the FMD virus. Two predicted T-cell epitopes were identified that showed high binding affinity with MHC1 alleles (VQRSRQSTL and YHAEWDTGL) and high conservation with SAT2 African serotypes and were located within the VP1 and VP3 proteins, respectively. Only one epitope was predicted for B cells (LPATPEDAAH), which scored above the threshold in Bepipred linear epitope, Emini surface accessibility, and Kolaskar and Tongaonkar antigenicity and is located in VP3 protein. Molecular docking of the peptides (VQRSRQSTL and YHAEWDTGL) with the MHC1 allele showed satisfactory interaction with the binding sites of BoLA-HD6 using UCSF chimera 1.13.1 software. The peptide VQRSRQSTL showed remarkable hydrophobic interaction with the BoLA-HD6 allele, which was superior to the other peptides. This study is the first to propose a peptide vaccine against FMD SAT2 serotypes from a Sudanese isolate.