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.
