Identification, Characterization and Evaluation of Potential Vaccine Candidates for the Control and Management of Peste Des Petits Disease in Ruminants

Abstract

Peste des petits ruminants (PPR) is a highly contagious transboundary viral disease affecting small ruminants and causing major economic losses in sub-Saharan Africa, including Kenya. Current vaccines require strict cold-chain storage, limiting effective disease control in tropical regions. This study aimed to develop and evaluate a thermostable multi-epitope subunit vaccine targeting the Fusion (F) and Hemagglutinin (H) proteins of Peste des petits ruminant virus (PPRV). Bioinformatics tools were used to predict B- and T-cell epitopes from selected immunogenic amino acid sequences. A total of 82 H-protein and 94 F-protein sequences were retrieved from the National Centre for biotechnology information (NCBI) database and analyzed using bioinformatics and immunoinformatics tools. Conserved B- and T-cell epitopes were identified, characterized for antigenicity, allergenicity, toxicity, and immunogenicity, these were assembled into a multi epitope vaccine construct with suitable linkers and adjuvant sequences (Gotsman et al., 2006). The final construct had 620 amino acid residues amongst which 51.6% were predicted to be exposed, 20.7% to be medium exposed while (28.2%) were predicted to be buried. A total of 70 amino acid residues were predicted to be located in disordered regions while 550 were predicted to be located in ordered regions. The Model with the lowest Root-mean-square-deviation of atomic position (RMSD) score of 9.6982, was later chosen for refinement. The predicted vaccine construct had a molecular weight (MW) of 65361.99 Da with a theoretical isoelectric point (pI) of 5.70. The Grand Average of Hydropathy (GRAVY) was predicted to be -0.165 and a half-life of more than >10h in vivo in E. coli and >30h in vitro in mammalian reticulocytes. The vaccine was predicted as stable with instability Index of 21.20, estimated aliphatic index of 92.34 and GDI-HA scores slightly above 0.9, with MolProbability score of 2.619. There was positive correlation between Test vaccine candidate and a Positive (N/75), which was statistically significant (r=+0.95, n=10, p <0.001, (2-tailed). Close similarity was observed between the tested strains. These findings indicate that the vaccine candidate is a promising thermostable subunit vaccine for controlling PPRV in small ruminants.